{ "name": "Spiral Staircase, chapter by chapter", "description": "Each chapter of the book as now sold: its start-here actions and further actions with their evidence grades, its mismatch card, its skeptic's box and the popular claims it grades.", "source": { "site": "https://www.spiralstaircase.com", "book": "Spiral Staircase: How Your Ancient Body Navigates the Modern World", "edition": "Revised Second Edition", "author": "Neil P. Bostick", "year": 2026, "isbn": "9798176270860" }, "citation": "Bostick, N.P. (2026). Spiral Staircase: How Your Ancient Body Navigates the Modern World, Revised Second Edition. ISBN 9798176270860.", "terms": "Quoting with attribution and a link is welcome, including in a generated answer, provided the evidence grade travels with the claim. Attribute findings to the study that produced them, not to this site. Full terms: https://www.spiralstaircase.com/terms", "grades": { "strong": "Multiple randomized controlled trials, or consistent large cohort studies with a well-understood mechanism.", "probable": "Good observational evidence with a plausible mechanism, or small or few trials.", "emerging": "Early, small, animal-only, or actively contested.", "note": "A claim quoted without its grade has had the most useful part removed. An emerging claim repeated as settled is a misquotation." }, "notMedicalAdvice": "Educational material about published research. Not medical advice, and not a reason to stop, skip or adjust a prescribed treatment. Several recommendations carry conditions naming who should consult a clinician first; those conditions are part of the recommendation.", "count": 16, "data": [ { "id": "1-the-short-version", "number": 1, "title": "The Short Version", "topic": "The short version: the five things that matter most", "part": "The Short Version", "url": "https://www.spiralstaircase.com/book/1-the-short-version", "startHere": [ { "action": "If you smoke, quit with help", "grade": "strong", "grades": [ "strong" ], "scope": [ { "grade": "strong", "text": null } ], "detail": "How: ask a doctor, pharmacist or quitline for varenicline or combination nicotine replacement (a patch plus gum, lozenges or spray), or switch completely to a regulated nicotine e-cigarette as a stepping-stone off cigarettes. Keep the break, change the place: if cigarettes come with company, take breaks where nobody smokes. Why: nothing else in this book moves your odds as far." }, { "action": "Walk more than you do now, toward seven or eight thousand steps a day", "grade": "strong", "grades": [ "strong", "probable" ], "scope": [ { "grade": "strong", "text": "for the curve" }, { "grade": "probable", "text": "for the number" } ], "detail": "You do not need 10,000. How: add one twenty-minute walk a day, about two thousand brisk steps; brisk means about a hundred steps a minute, so count your steps for fifteen seconds and aim for twenty-five. Make it a default: walk to something, on a fixed route, at a fixed time. Build up over weeks; sore feet and shins are the usual price of a sudden jump. Why: the steepest part of the curve is at the bottom." }, { "action": "Lift twice a week, about half an hour each time", "grade": "strong", "grades": [ "strong", "probable" ], "scope": [ { "grade": "strong", "text": "for strength" }, { "grade": "probable", "text": "for longer life" } ], "detail": "How: four or five moves that work the major muscle groups with what you have: sit-to-stands from a chair, push-ups against a wall or counter, rows with a band or a loaded backpack, carrying shopping bags. Do two or three rounds of each, stopping each set while a couple more good repetitions would still be possible; you need not push to failure. Add repetitions first, then load. Why: in the trials behind the guidance, training beat no training for strength and everyday function." }, { "action": "Swap the ultra-processed meals you eat most often", "grade": "probable", "grades": [ "probable" ], "scope": [ { "grade": "probable", "text": null } ], "detail": "How: pick the two or three meals you repeat most, such as breakfast and a work lunch, and rebuild them from ingredients: oats and fruit instead of a packaged bar, beans, eggs or leftovers instead of a vending-machine lunch. Keep the swaps boring and repeatable. Why: in a controlled trial, the same people ate about five hundred calories a day more when the food was ultra-processed." } ], "thenIfYouWantMore": [], "mismatchCard": {}, "skepticsBox": [ "Ranked lists flatter the ranker. This one rests on population averages, and your own order depends on where you start: for a non-smoker, the first item is already done. It weighs the size of each effect against the strength of the evidence, and that weighing is this book's judgment.", "Most of the evidence behind the five is observational. People who walk, lift, sleep at regular hours and keep close friends differ from people who do not in income, illness and a hundred unmeasured ways, and illness can cause inactivity, irregular sleep and isolation as easily as follow from them. Smoking is the exception, with half a century of consistent data and trials of the aids that help people stop. No one has ever randomized people to the whole package, and reading the death counts as a bill for how people live is an argument assembled across chapters, not a finding of any single study. The direction is consistent enough to act on; the round numbers are less precise than they look.", "Chapter 2 takes up the other half of the promise: where these expectations come from, how far evolution can be trusted, and where the ancestral story turns out to be wrong. From Chapter 3 on, each chapter takes one system in depth and ends with its own protocol and a Mismatch Card: what the system expects, what it gets, and what to do about the gap." ], "verdicts": [], "worksCited": 54 }, { "id": "2-what-your-body-expects-and-how-to-trust-this-book", "number": 2, "title": "What Your Body Expects, and How to Trust This Book", "topic": "How to trust health advice: what your body evolved to expect", "part": "The Short Version", "url": "https://www.spiralstaircase.com/book/2-what-your-body-expects-and-how-to-trust-this-book", "startHere": [ { "action": "Settle the dairy question with a two-week trial, not a DNA kit", "grade": "probable", "grades": [ "probable" ], "scope": [ { "grade": "probable", "text": null } ], "detail": "How: if milk reliably brings bloating, gas or cramps, switch to lactose-free dairy, or take a lactase enzyme with dairy, for two weeks. Then drink ordinary milk again on purpose and see what happens. Fermented dairy such as yogurt is often fine when milk is not. Why: losing lactase after childhood is the normal state for most adults on earth. Persistent gut symptoms still deserve a doctor, since celiac disease and inflammatory bowel disease can imitate lactose trouble." }, { "action": "Check one thing you already pay for (a habit, not a treatment)", "grade": null, "grades": [], "scope": null, "detail": "How: pick the supplement, powder or program you spend the most on. Find the study it rests on and ask the five questions above. If you cannot find a study, or it measured something else, stop buying it for a month. Why: the claims in the table above failed exactly this check." }, { "action": "If a drink turns your face red, whatever your background, treat it as a stop sign", "grade": "probable", "grades": [ "probable" ], "scope": [ { "grade": "probable", "text": null } ], "detail": "How: drink less, or not at all; the less you drink, the lower the risk. Do not hide the flush with antihistamines, antacids or products sold for the purpose, since that removes the warning and leaves the acetaldehyde. Why: the flush marks a slow-clearing enzyme and, with continued drinking, a substantially higher risk of cancer of the esophagus." } ], "thenIfYouWantMore": [], "mismatchCard": { "system": "The whole body, read on three clocks: genes over generations, development over a lifetime, physiology over days and weeks.", "what-it-expects": "The signals its long past supplied without anyone arranging them: hours on foot, real darkness, varied food, microbes, heat and cold, and familiar people close by.", "what-it-gets": "Too little of some signals (movement, daylight, fiber, company), too much of others (sugar, salt, evening light), and exposures that are new (nicotine is the classic example).", "what-happens-in-the-gap": "Many chronic diseases are suspected mismatches, graded chapter by chapter; local genetic tuning means the gap differs from person to person.", "the-handrail": "Restore missing signals on the fastest clock, physiology, and judge every claim by the study behind it. (●●○)", "strength-of-evidence": "●●○ The measured gaps between past and present are well documented; evolutionary explanations for particular diseases are mostly hypotheses, and the doses come from trials.", "see-also": "Chapters 1, 3, 5, 7, 16" }, "skepticsBox": [ "Evolutionary explanations are easy to invent and hard to test. The founders of the mismatch idea said early on that their evidence \"could only suggest testable hypotheses,\" and their claim that \"our genes have hardly changed\" collides with a genomic analysis concluding that human selection had \"accelerated greatly during the last 40,000 years.\" Knowing the story is not a cure, either. In one small randomized trial, adults given a web program framed around mismatch changed their activity and eating only slightly more than a control group, and the differences \"did not reach significance.\" That is why this book uses evolution only to decide where to look, and takes its doses from trials.", "What would weaken the frame? Gene variants that should help in traditional settings and harm in modern ones, sought in peoples now moving to towns, and not found. What would sink it? Trials in which restoring a missing signal, such as movement, daylight or company, did nothing. The chapters that follow report those trials, including the ones that found less than the enthusiasts claim." ], "verdicts": [ { "claim": "Avoid seed oils to lower inflammation", "verdict": "Against, as stated", "grade": "probable", "url": "https://www.spiralstaircase.com/verdicts/avoid-seed-oils-to-lower-inflammation" }, { "claim": "Drink raw milk", "verdict": "Against, and the risk is measured", "grade": "probable", "url": "https://www.spiralstaircase.com/verdicts/drink-raw-milk" }, { "claim": "Grounding, or earthing", "verdict": "Emerging and contested", "grade": "emerging", "url": "https://www.spiralstaircase.com/verdicts/grounding-or-earthing" }, { "claim": "Carnivore diet", "verdict": "Self-reported only, no trials", "grade": "emerging", "url": "https://www.spiralstaircase.com/verdicts/carnivore-diet" }, { "claim": "Mouth taping", "verdict": "Unsupported, with a safety catch", "grade": "emerging", "url": "https://www.spiralstaircase.com/verdicts/mouth-taping" }, { "claim": "Barefoot and minimal shoes", "verdict": "Probable for foot strength; unsupported for injury prevention", "grade": "probable", "url": "https://www.spiralstaircase.com/verdicts/barefoot-and-minimal-shoes" }, { "claim": "Cold plunges", "verdict": "A narrow effect on heat regulation; nothing on fat loss", "grade": "emerging", "url": "https://www.spiralstaircase.com/verdicts/cold-plunges" }, { "claim": "Avoid sunscreen", "verdict": "Against: the one trial runs the other way", "grade": "probable", "url": "https://www.spiralstaircase.com/verdicts/avoid-sunscreen" }, { "claim": "Detox teas, juice cleanses and similar", "verdict": "Unsupported", "grade": null, "url": "https://www.spiralstaircase.com/verdicts/detox-teas-juice-cleanses-and-similar" } ], "worksCited": 58 }, { "id": "3-the-body-that-walks", "number": 3, "title": "The Body That Walks", "topic": "Walking, sitting and steps: what the evidence says", "part": "The Body That Moves", "url": "https://www.spiralstaircase.com/book/3-the-body-that-walks", "startHere": [ { "action": "Walk every day, building toward 7,000 to 8,000 steps from wherever you are", "grade": "strong", "grades": [ "strong", "probable" ], "scope": [ { "grade": "strong", "text": "for the curve" }, { "grade": "probable", "text": "for the exact number" } ], "detail": "How: add a walk with a destination, to a shop or a friend's door, and lengthen it over weeks, not days. Under sixty, the gains keep coming up to about 8,000 to 10,000. Some of it should be brisk, about a hundred steps a minute (Chapter 1 gives a fifteen-second check). Why: the steepest drop in risk comes at the bottom, from about 3,000 steps to 5,000, so the least active gain the most." }, { "action": "Break up sitting every half hour", "grade": "probable", "grades": [ "probable" ], "scope": [ { "grade": "probable", "text": null } ], "detail": "How: stand and walk for two to five minutes, whether a lap of the house, a trip to the water tap or the long way to the bathroom. Set a timer, or tie it to something that already happens, like the end of each call. Why: walking breaks blunt the rise in blood sugar after meals, and walking beats standing." }, { "action": "Swap your table salt for a potassium-enriched salt substitute", "grade": "strong", "grades": [ "strong", "probable" ], "scope": [ { "grade": "strong", "text": "for blood pressure" }, { "grade": "probable", "text": "for strokes and deaths" } ], "detail": "How: buy one that lists potassium chloride among its ingredients and use it for cooking and at the table; the big trial used about one part potassium chloride to three parts ordinary salt. Why: it cuts sodium and adds potassium in a single move, and it lowered strokes in the largest trial. Do not use it if you have kidney disease, take potassium-sparing diuretics or potassium supplements, or take any medicine that limits how you clear potassium. If you take any blood-pressure or heart medicine, ask a clinician first. The WHO guideline does not cover pregnancy or children." } ], "thenIfYouWantMore": [], "mismatchCard": { "system": "The walking body: leg muscles and joints, heart and blood vessels, lymph, back and feet.", "what-it-expects": "Hours on foot most days, rest in squats and on the ground, little salt and plenty of potassium, and use of a sore body while it heals.", "what-it-gets": "Nearly eight sedentary hours a day and about 5,100 steps for the average American, about 11 g of salt a day worldwide, and rest, scans and fear after injury.", "what-happens-in-the-gap": "Higher blood sugar within hours of sitting, blood pressure that climbs with age, knee arthritis in American skeletons that has doubled beyond what age and weight explain, and back pain that hardens into disability.", "the-handrail": "Walk toward 7,000 to 8,000 steps, break up sitting, swap to potassium-enriched salt where safe, and keep moving through back pain (●●○)", "strength-of-evidence": "●●○ Trials firmly link movement, salt and potassium to blood sugar, blood pressure and pain, but the step numbers and the fitness link to long life rest on cohorts.", "see-also": "Chapters 1, 4, 5, 8, 11, 13, 14" }, "skepticsBox": [ "Almost everything behind this chapter's numbers is observational. People who walk a lot differ from those who walk little in income, illness and a hundred unmeasured ways, and sick people move less, so illness can drive the inactivity. Exercise trials run for months and measure blood pressure or fitness, not decades and deaths; a five-year trial in Norwegians in their seventies found no significant effect on deaths. The salt-substitute case for fewer deaths rests largely on one trial in rural China, in older people at high risk. Pain reprocessing therapy rests on one full trial, treated by experts in the method; two of its authors had commercial ties to it. The ancestral figures, such as the Tsimane's steps, show that the old signal was large; they do not show that you need to match it, and no trial has asked." ], "verdicts": [ { "claim": "Sitting is the new smoking", "verdict": "Exaggerated about tenfold", "grade": "probable", "url": "https://www.spiralstaircase.com/verdicts/sitting-is-the-new-smoking" }, { "claim": "You need 10,000 steps a day", "verdict": "A round number, not a threshold", "grade": "probable", "url": "https://www.spiralstaircase.com/verdicts/you-need-10-000-steps-a-day" }, { "claim": "Barefoot or minimalist shoes fix your feet", "verdict": "Stronger feet, yes, slowly; fewer injuries or better balance, unproven", "grade": "probable", "url": "https://www.spiralstaircase.com/verdicts/barefoot-and-minimal-shoes" } ], "worksCited": 101 }, { "id": "4-load-strength-and-bone", "number": 4, "title": "Load, Strength and Bone", "topic": "Strength training and bone health: what the evidence says", "part": "The Body That Moves", "url": "https://www.spiralstaircase.com/book/4-load-strength-and-bone", "startHere": [ { "action": "Two strength sessions a week, 20 to 30 minutes each", "grade": "strong", "grades": [ "strong" ], "scope": [ { "grade": "strong", "text": null } ], "detail": "How: work every major muscle group, meaning legs, hips, back, chest and arms, on two separate days; the no-gym week below is one way. Why: in trials, training builds strength at every age studied; in cohorts, this amount is also linked to longer life (●●○)." }, { "action": "Reach the daily protein range for your age", "grade": "probable", "grades": [ "probable" ], "scope": [ { "grade": "probable", "text": null } ], "detail": "How: for a 155-pound person, the official minimum is roughly 55 grams a day and the current US goal 85 to 110 grams. Over 65, do not drop below about 70 to 85 grams, the expert-group floor; the upper part of the US range suits active older adults. In lifting trials, more than about 110 grams stopped adding muscle. (Per pound of body weight: the minimum is a little over a third of a gram, the US goal half to three-quarters of a gram, the over-65 floor about half a gram.) A protein food at each meal, such as eggs, yogurt, fish, beans, tofu or meat, is the easy way to get there (Chapter 5 covers the rest of the plate). Why: enough protein helps training build a little more muscle, and expert panels judge that older muscle needs more." }, { "action": "Over 50, or told you have low bone mass: add heavier and impact loading, learned in person", "grade": "probable", "grades": [ "probable" ], "scope": [ { "grade": "probable", "text": null } ], "detail": "How: once the basic session feels easy, work with a physical therapist or qualified trainer toward heavier lifts and impact training (moves that jolt the skeleton, such as landing from a jump), as LIFTMOR's women did; the loads are heavy and form matters. If a trainer is out of budget, ask your doctor whether a physical therapy referral is covered. Why: this kind of training raised spine density in a trial of women with thin bones, while walking alone barely registers." } ], "thenIfYouWantMore": [], "mismatchCard": { "system": "Skeletal muscle and bone, which calibrate their strength to the loads they carry.", "what-it-expects": "Daily walking, carrying and lifting, often heavy, across a whole life.", "what-it-gets": "Chairs, wheels and machines; little that is heavy; and, for women, a menopausal transition that speeds bone loss with no extra load to answer it.", "what-happens-in-the-gap": "Strength falls faster than size, bone thins where load is missing, and the losses show up decades later as weakness, falls and fractures.", "the-handrail": "Two short strength sessions a week, enough protein for your age, and heavier loading for bone after 50 (●●○).", "strength-of-evidence": "●●○ Resistance training reliably builds strength in trials, but the links to longer life come from cohorts, and the bone evidence rests on one heavy-lifting trial measured by density.", "see-also": "Chapters 3, 5, 9, 15, 16" }, "skepticsBox": [ "Much of this chapter rests on markers and cohorts. Grip and the sitting-rising test predict death, but no study has shown that raising your grip lengthens your life; strong people differ from weak ones in many ways, and illness can cause weakness as well as follow it. The strength-and-mortality curve is cohort data too, and the Dallas figures come from well-off men only. LIFTMOR was a single trial of about a hundred women over eight months, and it measured bone density and function, a stand-in for fractures rather than fractures themselves. The protein targets for older people come from expert panels, not long trials, and the creatine evidence, while consistent, comes from many small studies in a field with industry ties; several authors of the safety review have them. What stands on firmer ground is narrower and still worth a great deal: training builds strength at every age studied, and balance and strength work cuts falls in trials." ], "verdicts": [ { "claim": "An ice bath after lifting helps you recover", "verdict": "Wrong if building muscle is the goal", "grade": "probable", "url": "https://www.spiralstaircase.com/verdicts/an-ice-bath-after-lifting-helps-you-recover" }, { "claim": "More protein is always better", "verdict": "False", "grade": "strong", "url": "https://www.spiralstaircase.com/verdicts/more-protein-is-always-better" } ], "worksCited": 51 }, { "id": "5-eat", "number": 5, "title": "Eat", "topic": "What to eat, and ultra-processed food: the evidence", "part": "The Body That Eats", "url": "https://www.spiralstaircase.com/book/5-eat", "startHere": [ { "action": "Cut the ultra-processed share first, beginning with sugary drinks and processed meat", "grade": "probable", "grades": [ "probable" ], "scope": [ { "grade": "probable", "text": null } ], "detail": "How: swap sugary drinks, including energy drinks, for water, tea, coffee or sparkling water; keep juice to a small glass; make bacon, ham and hot dogs occasional; change what is in the cupboard, so the easy option at home is food that was recently an ingredient. Start with the meals you eat most often. Why: in controlled feeding, people ate about five hundred calories a day more on ultra-processed menus, and drinks and processed meat carry the clearest long-term signals." }, { "action": "Build meals on plants, legumes, and minimally processed protein and fats", "grade": "probable", "grades": [ "probable" ], "scope": [ { "grade": "probable", "text": null } ], "detail": "How: fill half the plate with vegetables and fruit, a quarter with whole grains or potatoes, a quarter with protein, often beans, lentils or fish; cook with olive or another liquid plant oil; add a handful of nuts most days. Work up to at least 25 grams of fiber a day, slowly, to limit gas; in practice that means beans or lentils most days, whole grains in place of white bread and rice, and fruit or vegetables at every meal. Include a fermented food with live cultures most days, such as plain yogurt, kefir or kimchi (●○○; one small trial, see Chapter 6). Why: this is the pattern with trial support for heart events, and it lowered blood pressure within weeks (●●● for blood pressure)." }, { "action": "Drink to thirst", "grade": "probable", "grades": [ "probable" ], "scope": [ { "grade": "probable", "text": null } ], "detail": "How: water with meals and when thirsty; coffee, tea, milk and water-rich food all count. Drink more in heat and hard exercise, and in long events never drink past thirst. Why: thirst is the one intake signal the modern world has left mostly intact." } ], "thenIfYouWantMore": [], "mismatchCard": { "system": "Appetite and fuel: the gut, liver, muscle and fat, and the reward circuits that steer eating.", "what-it-expects": "Food that took work to get and time to chew, sugar wrapped in fiber, alcohol at a fraction of a percent, and water when thirsty.", "what-it-gets": "More than half its calories from ultra-processed food, sugar and alcohol in concentrated drinks, and little physical work.", "what-happens-in-the-gap": "People eat more without trying, surplus fat overflows into the liver and muscle, and diabetes climbs, as it did along the Gila.", "the-handrail": "Fewer ultra-processed foods; meals built on plants, legumes and minimally processed protein and fats; water to thirst; little or no alcohol (●●○)", "strength-of-evidence": "●●○ Feeding trials and diet-pattern trials agree on direction; most food-by-food evidence is observational, and the best mix of fat and carbohydrate is still argued.", "see-also": "Chapters 2, 3, 4, 6, 15" }, "skepticsBox": [ "The loudest diet argument is carbohydrates against calories. One camp holds that fast-digesting carbohydrates drive fat storage through insulin, the other that total intake decides. In a second NIH ward study, adults eating freely took in about seven hundred calories a day less on a low-fat, plant-based diet than on a very-low-carbohydrate, animal-based one. In a year-long trial, healthy low-fat and healthy low-carbohydrate diets did about equally well. Quality seems to matter more than the ratio. \"Ultra-processed\" may not survive as a scientific category either: French food specialists sorting the same foods agreed poorly on which were ultra-processed, and the feeding trials are small and short. Most food-by-food findings come from cohorts, where people who eat beans and nuts also differ in income, smoking and exercise. What would change this chapter: long trials showing that the processing itself, with calories, fiber and speed of eating held equal, does no harm." ], "verdicts": [ { "claim": "Everyone should wear a glucose monitor to find their spikes", "verdict": "No evidence of benefit for people without diabetes", "grade": "emerging", "url": "https://www.spiralstaircase.com/verdicts/everyone-should-wear-a-glucose-monitor-to-find-their" }, { "claim": "Seed oils such as soybean, corn and canola are inflammatory poisons behind modern disease", "verdict": "Unsupported as stated", "grade": "probable", "url": "https://www.spiralstaircase.com/verdicts/avoid-seed-oils-to-lower-inflammation" }, { "claim": "Drink at least eight glasses of water a day", "verdict": "False as a rule", "grade": "probable", "url": "https://www.spiralstaircase.com/verdicts/drink-at-least-eight-glasses-of-water-a-day" } ], "worksCited": 131 }, { "id": "6-the-gut-that-expects-dirt", "number": 6, "title": "The Gut That Expects Dirt", "topic": "Gut health, fiber and allergies: what the evidence says", "part": "The Body That Eats", "url": "https://www.spiralstaircase.com/book/6-the-gut-that-expects-dirt", "startHere": [ { "action": "Eat more fiber, from many kinds of plant", "grade": "probable", "grades": [ "probable" ], "scope": [ { "grade": "probable", "text": null } ], "detail": "How: beans or lentils most days (Chapter 5's third of a cup counts), whole grains instead of white, and a fruit or vegetable at every meal; frozen vegetables and canned beans count. A medium apple carries about 4 grams, so together these moves take a typical day from about 17 grams toward 25 or more. Build up slowly to limit gas. Why: it feeds the colon's bacteria, and high intakes are consistently linked to lower death rates." }, { "action": "Add one serving of fermented food with live cultures a day, and build up if you like it", "grade": "emerging", "grades": [ "emerging" ], "scope": [ { "grade": "emerging", "text": null } ], "detail": "How: a normal portion, such as a pot of plain yogurt, a glass of kefir, or a forkful or two of kimchi or sauerkraut from the chilled aisle; miso and most cheeses count too. Bread, vinegar pickles and heat-treated products carry no live microbes. Expect some bloating at first. Why: one small trial is promising, and cheap, old food has little downside." }, { "action": "Parents of babies: introduce peanut and well-cooked egg early, and keep them in the diet", "grade": "strong", "grades": [ "strong", "probable" ], "scope": [ { "grade": "strong", "text": "for peanut in high-risk babies" }, { "grade": "probable", "text": "for egg and other babies" } ], "detail": "" } ], "thenIfYouWantMore": [], "mismatchCard": { "system": "The gut's microbes and the immune system's learned tolerance.", "what-it-expects": "Tens of grams of fiber a day from many plants; microbes from siblings, animals, soil and food; early tastes of lifelong foods; fever and care while sick.", "what-it-gets": "About 17 g of fiber a day (the US adult average), small families and indoor lives, needless antibiotics, delayed allergenic foods until recently, and fear of the thermometer.", "what-happens-in-the-gap": "Fewer gut species, more allergy, autoimmune disease diagnosed in about one person in ten in the UK over two decades (mostly women), resistant bacteria and returning measles.", "the-handrail": "More fiber from more plants, a daily fermented food, early peanut and egg, antibiotics only when needed, vaccines on schedule. (●●○)", "strength-of-evidence": "●●○ Trials show food tolerance can be taught and vaccines work; fiber's links are strong but observational; proof that lost microbes cause disease in people rests largely on mice.", "see-also": "Chapters 2, 5, 15, 16" }, "skepticsBox": [ "Microbiome science has a hype problem. Of 38 published studies that transplanted human gut microbes into rodents, 36 reported transferring a disease, a success rate the reviewers called \"implausible.\" Much of the case that microbes shape mood or weight rests on such animals. The farm and pet studies are observational, and farm families differ in many ways. Bottling the old environment has failed so far: worm treatments for bowel disease faded in larger placebo-controlled trials, and a bacterial extract did not prevent wheezing illness in high-risk young children. Fiber's record is strongest in cohorts; two large trials of bran or a high-fiber diet did not stop bowel polyps from returning. And lowering a fever has not changed survival in human trials either way. The firmest ground in this chapter is the peanut trials, the vaccines, and antibiotic stewardship. What would change the picture: a randomized trial in which a microbial exposure, not a food, prevented allergy or autoimmune disease in people." ], "verdicts": [ { "claim": "Probiotic pills fix your gut", "verdict": "For healthy people, unsupported; spend the money on yogurt and beans", "grade": "probable", "url": "https://www.spiralstaircase.com/verdicts/probiotic-pills-fix-your-gut" }, { "claim": "A scoop of greens powder covers your vegetables", "verdict": "Expensive vitamins, and no substitute for vegetables", "grade": "emerging", "url": "https://www.spiralstaircase.com/verdicts/a-scoop-of-greens-powder-covers-your-vegetables" }, { "claim": "A \"leaky gut\" is behind your symptoms", "verdict": "Real in specific diseases, unproven as an everyday diagnosis", "grade": "emerging", "url": "https://www.spiralstaircase.com/verdicts/a-leaky-gut-is-behind-your-symptoms" }, { "claim": "Raw milk is healthier", "verdict": "Unsupported, and the risk is measured", "grade": "probable", "url": "https://www.spiralstaircase.com/verdicts/drink-raw-milk" } ], "worksCited": 77 }, { "id": "7-light-and-dark", "number": 7, "title": "Light and Dark", "topic": "Light, the body clock and vitamin D: where to start", "part": "The Body That Reads Signals", "url": "https://www.spiralstaircase.com/book/7-light-and-dark", "startHere": [ { "action": "Get outdoor daylight early in your day, roughly 10 to 30 minutes", "grade": "probable", "grades": [ "probable" ], "scope": [ { "grade": "probable", "text": null } ], "detail": "How: within an hour of waking, step outside, not behind glass: walk part of the commute, coffee on the step, the dog. Longer when gray or shaded; open sky beats a courtyard; a lunchtime walk outside counts too. Sunglasses are fine. Why: morning light pulls the clock earlier, and outdoors is many times brighter than indoors." }, { "action": "Dim the last two to three hours before bed", "grade": "probable", "grades": [ "probable" ], "scope": [ { "grade": "probable", "text": null } ], "detail": "How: switch off overhead lights and use one or two low lamps, warm white if you are buying bulbs; turn screen brightness down. Many ordinary warm-white bulbs, kept low, already meet the level sleep researchers suggest for the evening. Why: an ordinary living room is bright enough to delay melatonin, and people differ so much in sensitivity that it is better to judge by your own sleep than to chase a number." }, { "action": "Get children outdoors about two hours a day; less still helps", "grade": "strong", "grades": [ "strong" ], "scope": [ { "grade": "strong", "text": null } ], "detail": "How: recess, walking to school, afternoons in the park, weekends outside. Shade and gray skies count; indoor sport did not show the same link. It matters most from school entry on, and in one trial a forty-minute outdoor class each school day helped. Why: outdoor time roughly halves new cases in trials, and Taiwan set two hours as its school target. It prevents new cases more than it slows existing ones (●○○ for slowing)." } ], "thenIfYouWantMore": [], "mismatchCard": { "system": "The circadian clock, set through melanopsin in the eye; skin pigment and vitamin D; the growing eye.", "what-it-expects": "Bright days, truly dark nights, sun matched to skin and changing with the seasons, and a childhood spent largely outdoors.", "what-it-gets": "Days mostly indoors under room light far dimmer than any sky, evenings lit brightly enough to hold the clock back, lit bedrooms, pale skin under sudden holiday sun and dark skin in indoor lives, and classrooms instead of fields.", "what-happens-in-the-gap": "The clock drifts later, sleep timing scatters, vitamin D runs low in some skins while sunburn and skin cancer rise in others, and children's eyes grow too long.", "the-handrail": "Morning daylight outdoors, dim evenings, a dark bedroom, unburnt sun matched to skin type, vitamin D where sun falls short, and two hours outside for children (●●○)", "strength-of-evidence": "●●○ Light's effect on the clock and outdoor time's effect on myopia rest on trials; the links from light to disease and death rest on observational cohorts, and vitamin D pills have not prevented major disease in adults who had enough.", "see-also": "Chapters 1, 2, 8, 12, 16" }, "skepticsBox": [ "The light-and-mortality results are observational. A week of wrist data stands in for years, sleeves cover sensors, and bright nights come with differences in health, housing and work. The two senior authors of the largest study co-founded a circadian-health company and have taken funding from lighting manufacturers. That does not make the sensors lie, but it is a reason to wait for other cohorts. The camping studies are tiny, and nobody has tested the morning hour or the ten to thirty minutes. The case for outdoor time in children is stronger, yet its effects are modest: in a Guangzhou trial, a daily outdoor class left a gap of nine percentage points over three years, and the light mechanism is proven only in animals. Taiwan's national fall came from an eye chart, and careful measurements in Taipei show second-grade myopia still creeping up, more slowly. Genes set who is susceptible to myopia; environment sets how many. Vitamin D has the opposite problem, with strong associations and weak trials, because most trial volunteers already had enough. A large trial in people who are truly deficient would change the picture." ], "verdicts": [ { "claim": "Blue-blocking glasses protect your sleep from screens", "verdict": "Mostly unsupported; skip the glasses unless a clinician suggests them for a specific sleep problem", "grade": "strong", "url": "https://www.spiralstaircase.com/verdicts/blue-blocking-glasses-protect-your-sleep-from-screens" }, { "claim": "Ten minutes of morning sunlight sets your body clock for the day", "verdict": "Right direction, invented number", "grade": "probable", "url": "https://www.spiralstaircase.com/verdicts/ten-minutes-of-morning-sunlight-sets-your-body-clock" }, { "claim": "Sunscreen is dangerous, and you are better off without it", "verdict": "The danger claim is unsupported, and the one long trial runs the other way", "grade": "strong", "url": "https://www.spiralstaircase.com/verdicts/avoid-sunscreen" } ], "worksCited": 87 }, { "id": "8-sleep", "number": 8, "title": "Sleep", "topic": "Sleep: what the evidence says, and where to start", "part": "The Body That Reads Signals", "url": "https://www.spiralstaircase.com/book/8-sleep", "startHere": [ { "action": "Get up at the same time every day, weekends included", "grade": "probable", "grades": [ "probable" ], "scope": [ { "grade": "probable", "text": null } ], "detail": "How: pick a wake time you can keep on your busiest day, and hold it on Saturday too. After a bad night, get up anyway. Why: regular timing predicted survival better than duration did in the largest measured study, though it is observational." }, { "action": "Make the bedroom dark, cool and quiet, with the phone charging somewhere else", "grade": "probable", "grades": [ "probable", "emerging" ], "scope": [ { "grade": "probable", "text": "for dark, for sleep timing" }, { "grade": "emerging", "text": "for cool, for the phone in adults, and for heart and metabolic effects" } ], "detail": "How: blackout curtains or a blind that works; tape or cover standby lights; let the room cool through the night and adjust the bedding instead of chasing a number on the thermostat; earplugs if noise wakes you. Put a cheap alarm clock by the bed and the phone across the room or outside it. Why: light late in the day pushes the body clock later, and screens in bed go with less sleep." }, { "action": "If insomnia has lasted three months or more, ask for CBT-I before sleeping pills", "grade": "strong", "grades": [ "strong" ], "scope": [ { "grade": "strong", "text": null } ], "detail": "How: ask your doctor for it by name. It works by telephone; in one trial it took six calls over eight weeks. Courses and apps also exist, so ask which ones your doctor trusts. Why: it is the recommended first treatment for every adult with chronic insomnia. Do not stop a prescribed sleep medicine abruptly without medical advice." } ], "thenIfYouWantMore": [], "mismatchCard": { "system": "The circadian clock and the sleep it schedules, tuned by light, temperature and routine.", "what-it-expects": "A bright day, a dark night that cools, and the same timing tomorrow; enough sleep, with room for naps.", "what-it-gets": "Dim days, lit evenings, a bedroom at one temperature with a phone in it, a schedule that lurches at weekends, afternoon caffeine, and for some, work through the night.", "what-happens-in-the-gap": "Sleep moves later and grows irregular; insomnia is common and often untreated; night workers live against their own clocks; apnea goes undiagnosed, especially in women after menopause.", "the-handrail": "A fixed wake time, a dark and cooling bedroom without a phone, CBT-I for chronic insomnia, and snoring taken seriously. (●●○)", "strength-of-evidence": "●●○ CBT-I and the apnea treatments rest on trials; the regularity link rests on a large but observational cohort; the shift-work fixes on laboratory simulations.", "see-also": "Chapters 1, 5, 7, 9, 10, 11, 13, 15" }, "skepticsBox": [ "The regularity finding, the chapter's headline, rests on observational cohorts: irregular sleepers differ in work, health and income, and statistics cannot fully remove those differences. The forager data come from small groups studied for weeks. Electric light has not measurably shortened adult sleep over half a century, which cuts against the story that modern life has stolen our hours. The shift-work advice is built from laboratory simulations in young volunteers, and the six-hour caffeine margin from a dozen people given a large dose, so your own cutoff may sit earlier or later. What would change the chapter: a randomized trial in which people assigned to regular sleep timing lived longer or stayed healthier than people who were not. Until then, regularity is the cheapest bet with the best odds, not a proven cure." ], "verdicts": [ { "claim": "Wait 90 minutes after waking before your first coffee", "verdict": "Untested, and the reasoning looks backward", "grade": "emerging", "url": "https://www.spiralstaircase.com/verdicts/wait-90-minutes-after-waking-before-your-first-coffee" }, { "claim": "Tart cherry juice and magnesium will fix your sleep", "verdict": "Unproven", "grade": "emerging", "url": "https://www.spiralstaircase.com/verdicts/tart-cherry-juice-and-magnesium-will-fix-your-sleep" }, { "claim": "NSDR or yoga nidra can stand in for lost sleep", "verdict": "A pleasant way to rest, not a substitute for sleep", "grade": "emerging", "url": "https://www.spiralstaircase.com/verdicts/nsdr-or-yoga-nidra-can-stand-in-for-lost-sleep" }, { "claim": "Taping your mouth shut at night improves sleep and breathing", "verdict": "Unsupported for self-treatment, and possibly risky", "grade": "emerging", "url": "https://www.spiralstaircase.com/verdicts/mouth-taping" } ], "worksCited": 85 }, { "id": "9-heat-and-cold", "number": 9, "title": "Heat and Cold", "topic": "Cold exposure, sauna and heat: what the evidence says", "part": "The Body That Reads Signals", "url": "https://www.spiralstaircase.com/book/9-heat-and-cold", "startHere": [ { "action": "Let your home move a little: cooler rooms in winter, and a bedroom that cools at night", "grade": "emerging", "grades": [ "emerging" ], "scope": [ { "grade": "emerging", "text": null } ], "detail": "How: in winter, set the thermostat around 64 to 66°F and add a sweater rather than a degree; turn the heat down at bedtime so the bedroom cools overnight (Chapter 8 covers sleep). Why: a few weeks of mild cold grew brown fat and improved insulin sensitivity in tiny trials. Safety: the World Health Organization treats 64°F as a safe indoor floor in cold seasons, and older people, infants and anyone with heart or lung disease may need it warmer." }, { "action": "End your shower with thirty seconds of cold, if you like it and your heart is healthy", "grade": "probable", "grades": [ "probable", "emerging" ], "scope": [ { "grade": "probable", "text": "for fewer sick days" }, { "grade": "emerging", "text": "for anything else" } ], "detail": "How: finish a normal warm shower with thirty seconds of cold; longer did no better. Breathe slowly through the first gasp. Why: in the one large trial, it cut sickness absence by about three in ten, though not illness itself. Safety: with heart disease or an irregular heartbeat, ask a clinician first." }, { "action": "Heat: a sauna or a hot bath, a few times a week, if you have access and enjoy it", "grade": "emerging", "grades": [ "emerging" ], "scope": [ { "grade": "emerging", "text": null } ], "detail": "How: about a quarter of an hour in a sauna, or a hot bath around 104°F for ten minutes or so. Taken an hour or two before bed, a warm bath or shower shortened the time people took to fall asleep in pooled studies (Chapter 8). Why: two large cohorts link regular heat with fewer heart deaths (that link is ●●○; the frequency is untested), and small trials show better artery function in unfit people. Safety: no alcohol, drink water, rise slowly, and see \"Safety\" below." } ], "thenIfYouWantMore": [], "mismatchCard": { "system": "Thermoregulation: skin blood flow, shivering muscle, brown fat, sweating and the heart's response to heat.", "what-it-expects": "Days and seasons that leave the comfortable band: cool mornings, warm afternoons, nights that cool, and occasional real cold and real heat.", "what-it-gets": "A narrow indoor band all year, most of life spent inside, offices set for a man in a suit, and summers whose humid heat can outrun the body's cooling.", "what-happens-in-the-gap": "Cold acclimatization fades within a few years of the signal stopping, as the haenyeo showed, though the metabolic cost appears small, and a body that rarely meets heat has had no practice at shedding it.", "the-handrail": "Mild, regular swings in both directions: cooler rooms, a brief cold finish to the shower, sauna or hot baths, and respect for cold water and humid heat (●○○ to ●●○)", "strength-of-evidence": "●●○ Acclimatization and its loss are well documented, and regular heat tracks lower cardiovascular death in two cohorts, but the cold trials are small, the one large shower trial measured absence rather than illness, and several heat trials are null.", "see-also": "Chapters 4, 8, 15" }, "skepticsBox": [ "The sauna story rests almost entirely on one Finnish cohort of men, analyzed again and again by one research group. Its comparison group is men who took a sauna once a week, not never, and only about two hundred men sat in the top group. Letters in reply ran under the title \"The link between sauna bathing and mortality may be noncausal.\" The Japanese bathing study is independent support, and also observational.", "The cold-shower trial was unblinded and counted days absent, not days ill. The trials that trained brown fat were tiny, and pooled studies of cold found no change in fasting blood sugar, insulin or triglycerides.", "The strongest objection is simpler: the thermal bubble saves lives. Cold still kills far more people than heat, and air conditioning is why hot days no longer kill Americans as they once did. Nothing here argues for a cold house. What would change the picture is a trial of regular sauna or mild cold that counts heart attacks and deaths, and the Finnish findings repeated in women and outside Finland." ], "verdicts": [ { "claim": "Brown fat will make you lean", "verdict": "Oversold", "grade": "probable", "url": "https://www.spiralstaircase.com/verdicts/brown-fat-will-make-you-lean" }, { "claim": "Cold water raises dopamine by 250%", "verdict": "A real number, misapplied", "grade": "emerging", "url": "https://www.spiralstaircase.com/verdicts/cold-water-raises-dopamine-by-250" }, { "claim": "Eleven minutes of cold and fifty-seven minutes of heat a week is the optimal protocol", "verdict": "Not a protocol", "grade": "emerging", "url": "https://www.spiralstaircase.com/verdicts/eleven-minutes-of-cold-and-fifty-seven-minutes-of-heat" } ], "worksCited": 58 }, { "id": "10-green-and-quiet", "number": 10, "title": "Green and Quiet", "topic": "Nature, green space and noise: what the evidence says", "part": "The Body That Reads Signals", "url": "https://www.spiralstaircase.com/book/10-green-and-quiet", "startHere": [ { "action": "Spend about two hours a week somewhere green, including city parks", "grade": "probable", "grades": [ "probable" ], "scope": [ { "grade": "probable", "text": null } ], "detail": "How: four half-hour visits, or one long weekend walk, in any park, riverside, woodland or beach. Why: in a large English survey the benefit started around two hours, though a survey cannot prove direction." }, { "action": "Protect your hearing from loud noise", "grade": "strong", "grades": [ "strong" ], "scope": [ { "grade": "strong", "text": "for the exposure limits" } ], "detail": "How: use the arm's-length test. If you must raise your voice to talk to someone beside you, keep the time short, step away from the speakers, or wear earplugs; at concert volumes the safe daily allowance runs out within an hour. With headphones, keep the volume low enough to hear someone next to you. Why: noise damage to hearing is permanent and avoidable." }, { "action": "Get a hearing test if you are over 50 or struggling to follow conversation", "grade": "probable", "grades": [ "probable" ], "scope": [ { "grade": "probable", "text": "for hearing" }, { "grade": null, "text": "not graded for dementia" } ], "detail": "How: ask your doctor or an audiologist, and mention any ringing. One warning sign the Food and Drug Administration lists: \"You find it hard to follow speech in groups.\" In the United States, hearing aids for perceived mild to moderate loss have been sold over the counter since 2022, without a prescription or exam. Why: hearing loss is common, undertreated and easy to miss in yourself; no age is backed by a trial, and 50 is simply a sensible point to stop guessing." } ], "thenIfYouWantMore": [], "mismatchCard": { "system": "The stress system, attention and the heart, tuned by a living landscape; hearing, and the threat circuit it feeds.", "what-it-expects": "Daylight hours among plants, water and animals, and a quiet natural background broken by occasional sounds worth noticing.", "what-it-gets": "Most of life indoors, a view of a wall, and mechanical noise that never stops, including at night, with bursts loud enough to damage the ear.", "what-happens-in-the-gap": "Slower stress recovery, more psychiatric diagnoses among children raised in the least green places, extra heart and lung deaths where the trees go, broken sleep, and avoidable hearing loss on a population scale.", "the-handrail": "Two hours a week somewhere green, the arm's-length test for loud noise, a quiet bedroom, and a hearing test if conversation gets harder or once you are past 50 (●●○)", "strength-of-evidence": "●●○ Natural experiments, twin and mover designs and a randomized trial point the same way for green space, but individual effects are modest; noise exposure limits are solid, the noise-and-heart link is observational, and hearing aids have not been shown to prevent dementia.", "see-also": "Chapters 7, 8, 9, 13, 16" }, "skepticsBox": [ "The central objection never goes away: healthier, wealthier people live in greener places and visit parks more, and the designs built to beat it only half succeed. Identical twins kept the depression link but lost stress and anxiety, and in Denmark, adjustment shrank the excess risk of ADHD by nearly two-thirds; the authors wrote that their estimates \"fundamentally only show correlations.\" Exposure is crude, too: most studies use a satellite greenness score that cannot tell a grand elm from a weedy verge, and across the largest US cities, the greener ones had higher death rates, blamed partly on sprawl and driving. In Berlin, volunteers randomly sent on an hour's walk in a forest showed calmer activity in the brain's threat center than those sent down a shopping street, yet their felt and measured stress did not differ.", "On noise, the heart findings are observational, and people beside the loudest roads differ in more ways than decibels. On hearing and dementia, early dementia can itself make hearing worse, and damage to blood vessels could harm both ear and brain separately." ], "verdicts": [ { "claim": "Forest bathing works because trees release chemicals, called phytoncides, that boost your immune system and fight cancer", "verdict": "Enjoy the forest as relaxation, plausible though the size is uncertain; the tree-chemical immune story is unproven", "grade": "emerging", "url": "https://www.spiralstaircase.com/verdicts/forest-bathing-works-because-trees-release-chemicals" }, { "claim": "Walking barefoot on the earth, or sleeping on a grounding mat, lets electrons flow into your body and reduces inflammation", "verdict": "Unsupported", "grade": "emerging", "url": "https://www.spiralstaircase.com/verdicts/grounding-or-earthing" } ], "worksCited": 43 }, { "id": "11-the-social-animal", "number": 11, "title": "The Social Animal", "topic": "Loneliness and health: why connection matters", "part": "The Social Animal", "url": "https://www.spiralstaircase.com/book/11-the-social-animal", "startHere": [ { "action": "Name your three to five people, and schedule them", "grade": "probable", "grades": [ "probable" ], "scope": [ { "grade": "probable", "text": null } ], "detail": "How: write down the people you would call at two in the morning, and who would call you. Give each a recurring slot, in person where you can and a call where you cannot: the same Tuesday, the same table, the same walk. No trial has tested a dose, so pick a rhythm you can keep, such as a real conversation with one of them every week. If you can write only one name, or none, start there: pick one dormant tie, an old friend, a sibling or a former colleague, and send one message this week suggesting a specific time. Why: the health evidence points at the quality of a few close ties, not the size of a network." }, { "action": "Join one standing weekly thing done with other people", "grade": "emerging", "grades": [ "emerging" ], "scope": [ { "grade": "emerging", "text": null } ], "detail": "How: a class, a choir, a team, a volunteer shift, a shared meal. Same time, same faces, and if you can, something done together in time, such as singing, dancing, rowing or a group class. Choose what you will still be doing in three months over what sounds best. Why: recurrence is the likeliest way to build the ties linked to longer life, though that part is inference; moving in time raised closeness in single sessions." }, { "action": "Expecting or raising young children? Recruit helpers on purpose, before you need them", "grade": "emerging", "grades": [ "emerging" ], "scope": [ { "grade": "emerging", "text": null } ], "detail": "How: before the birth, line up specific people for specific jobs: meals, a night off, laundry, an adult to talk to at midday. If there are two of you, agree in advance who covers which nights. Ask in detail; offers of help tend to arrive vague. Why: low support is among the strongest predictors of depression after birth; no trial has tested a particular arrangement." } ], "thenIfYouWantMore": [], "mismatchCard": { "system": "The social brain and the stress physiology it regulates, from the threat circuitry that registers exclusion to the hormones that respond to touch.", "what-it-expects": "Daily, face-to-face contact with a small, stable group; touch as an ordinary event; many hands around every infant, from labor onward.", "what-it-gets": "A wide, thin network through a screen, inner circles left to chance, labor attended by rotating staff, and new parents largely alone behind a closed door.", "what-happens-in-the-gap": "Higher mortality among isolated and lonely people across dozens of cohorts, loneliness and depression in new parents, and a stress system that loses one of its regulators.", "the-handrail": "Three to five named people on a schedule, a standing weekly activity with others, touch where it is welcome, continuous labor support and help recruited before a birth (●●○)", "strength-of-evidence": "●●○ The mortality association is large and consistent but observational; the mechanisms and the labor-support effect rest on small or low-quality trials.", "see-also": "Chapters 1, 12, 13, 14, 15" }, "skepticsBox": [ "Almost every mortality number in this chapter is observational, and the arrow can run both ways. People who are already sick, poor or declining become more isolated, and isolation and ill health share causes that no adjustment fully removes. The size and consistency of the association across very different cohorts make a purely spurious link unlikely, but a trial that assigns people close friends is neither practical nor ethical, so the grade for cause and effect stays at ●●○. The mechanisms rest on small studies: thirteen students in a scanner, sixty-eight people in the touch trial, single dance sessions measured through pain threshold, a proxy. No trial has followed a year of choir into a hard health outcome. The layers of a network are averages, and the 150 at their edge has not survived reanalysis. The labor-support trials were rated low quality by their own reviewers. What would overturn the advice is a large, well-controlled study in which people who deliberately increased their contact saw no change in health, or a clean null result from a trial of social prescribing. Neither exists yet." ], "verdicts": [], "worksCited": 34 }, { "id": "12-attention-in-the-age-of-the-phone", "number": 12, "title": "Attention in the Age of the Phone", "topic": "Phones and attention: what screens do, and where to start", "part": "The Social Animal", "url": "https://www.spiralstaircase.com/book/12-attention-in-the-age-of-the-phone", "startHere": [ { "action": "Charge the phone outside the bedroom", "grade": "probable", "grades": [ "probable", "emerging" ], "scope": [ { "grade": "probable", "text": "for children and teens" }, { "grade": "emerging", "text": "for adults" } ], "detail": "How: a charger in the kitchen or hall and a cheap alarm clock by the bed. Why: an expert panel agreed that screen use before bed harms sleep in children and teens, where the evidence is firmest; among young adults, more screen time in bed goes with more insomnia and less sleep (Chapter 8)." }, { "action": "Turn off every notification that is not a person", "grade": "emerging", "grades": [ "emerging" ], "scope": [ { "grade": "emerging", "text": null } ], "detail": "How: in settings, leave on calls and messages from people; switch off news, shopping, games, likes and \"you might have missed\". Why: every alert is one more unpredictable payout on the slot-machine schedule. No trial has tested this on its own, but the cost of trying is a few minutes." }, { "action": "Use AI like a spotter, not a stand-in, whenever you want to learn or keep a skill", "grade": "probable", "grades": [ "probable" ], "scope": [ { "grade": "probable", "text": null } ], "detail": "How: ask for a hint, a question or a check of your own attempt before any finished answer; if the tool allows it, tell it to tutor rather than solve. Why: in the Turkish trial, the version that withheld answers gave the biggest gains and no exam penalty, while full answers cost students on the exam. If the only goal is the output, this does not apply." } ], "thenIfYouWantMore": [], "mismatchCard": { "system": "The reward circuit that learns from unpredictable payouts; the default network that runs during idle time; memory, navigation and reasoning that improve with use; and a child's play-driven development.", "what-it-expects": "Rewards that are earned, spaced and often absent; long stretches with nothing to attend to; problems solved with your own equipment; and childhood days of free, mixed-age, outdoor play.", "what-it-gets": "A pocket device engineered for time on device, paying out on a variable schedule and filling every gap; tools that supply the answer before the effort starts; and childhoods with hours of screens and the risk designed out.", "what-happens-in-the-gap": "Checking that resists unlearning, idle minutes that vanish, work that looks better while the person doing it learns less, and afternoons a phone ban empties but does not refill.", "the-handrail": "The phone out of the bedroom, notifications from people only, AI as a spotter, phone-free times, free outdoor play for children (●●○)", "strength-of-evidence": "●●○ One large randomized trial on adult social media and one strong field trial on AI and learning, set against a genuinely open argument about teenagers and a thin, mostly observational literature on play.", "see-also": "Chapters 1, 7, 8, 11, 13, 14" }, "skepticsBox": [ "Almost everything in this chapter is weaker than its headlines. The best adult trial is one study of paid Facebook users in 2018, before short-video apps took over; its effect is small, and it says nothing direct about teenagers. The Turkish trial is strong but covers one subject in one country, and it measured learning, not brain health; no study yet shows that AI use harms a healthy adult brain. The risky-play reviewers graded their own evidence very low quality. The school phone study is a single snapshot that cannot separate cause from selection. On teenagers, the timing and the pattern favor the alarm, the direct searches for large effects favor the skeptics, and reverse causation fits the long-term data about as well as harm does. What would settle it: trials that randomly assign whole schools or families to reduced use and follow the children for years. And the alarm itself is old. In Plato's Phaedrus, Socrates warns that writing will breed forgetfulness, because people will trust outside marks instead of their memory. He was right about the mechanism, and nobody proposes giving up writing." ], "verdicts": [ { "claim": "A digital detox resets your brain", "verdict": "A planned break brings a small lift and can reset a habit; \"resets your brain\" is overstated", "grade": "probable", "url": "https://www.spiralstaircase.com/verdicts/a-digital-detox-resets-your-brain" }, { "claim": "Screen time is destroying a generation", "verdict": "Unproven as stated, with a serious case on both sides; heavy use is a fair worry, and the causal claim is open", "grade": "emerging", "url": "https://www.spiralstaircase.com/verdicts/screen-time-is-destroying-a-generation" } ], "worksCited": 28 }, { "id": "13-stress-and-the-mind", "number": 13, "title": "Stress and the Mind", "topic": "Stress, anxiety and cortisol: what the evidence says", "part": "The Social Animal", "url": "https://www.spiralstaircase.com/book/13-stress-and-the-mind", "startHere": [ { "action": "Move most days, in whatever form you will keep doing", "grade": "strong", "grades": [ "strong" ], "scope": [ { "grade": "strong", "text": "for depressive symptoms, though most trials are at high risk of bias" } ], "detail": "How: walking or jogging, yoga, strength training or tai chi all counted in the trials. Build toward the 150 minutes a week of moderate activity that Chapter 3 sets out, and let some sessions get brisk enough to leave you breathing hard. A depressed body does not start at a runner's baseline, so begin with ten minutes out the door and build. Why: exercise produced moderate drops in depressive symptoms, and more intense sessions did somewhat more." }, { "action": "Practice slow breathing or mindfulness for five to ten minutes a day, or take an eight-week course", "grade": "probable", "grades": [ "probable" ], "scope": [ { "grade": "probable", "text": null } ], "detail": "How: breathe about six times a minute, roughly four seconds in and six out, sitting down, on most days; use a count, an app or a prayer to keep the pace. For anxiety that persists, consider an eight-week mindfulness-based stress reduction course. Why: small-to-moderate reductions in stress and anxiety in trials, and one course proved no worse than a standard drug for anxiety disorders." }, { "action": "Talk to a clinician if low mood or anxiety lasts more than two weeks or gets in the way of work, sleep or people", "grade": "strong", "grades": [ "strong" ], "scope": [ { "grade": "strong", "text": null } ], "detail": "How: a family doctor is a fine first stop. Before the appointment, write down what you have noticed, for how long, and what it is costing you in sleep, work and time with people, because a low day in the waiting room can make a hard month sound like nothing. Ask about the options, including talking therapy; if cost or a waiting list is the barrier, say so and ask about lower-cost and online options. Why: every antidepressant tested beat placebo; the wrong chemical story never meant the treatment was wrong. If you already take a psychiatric medicine, keep taking it; any change belongs in a conversation with the person who prescribed it." } ], "thenIfYouWantMore": [], "mismatchCard": { "system": "The stress response, fast adrenaline and slow cortisol, with the defensive emotions it drives: fear, anxiety and low mood.", "what-it-expects": "Threats that are physical, local and short, answered with the body, among allies who help solve problems.", "what-it-gets": "Uncontrollable judgment without end, low control at work, long hours, thin company and short sleep.", "what-happens-in-the-gap": "Alarms built to over-fire go off constantly and stop resetting; the daily cortisol rhythm flattens, tissues stop hearing it, inflammation runs on, and anxiety and low mood are common.", "the-handrail": "Movement most days, slow breathing or a mindfulness course, trusted company and control over your hours, and treatment when symptoms persist (●●○)", "strength-of-evidence": "●●○ Treatment effects and stress gradients rest on large trials and cohorts; the evolutionary explanations remain hypotheses, and the effect of adult stress on disease is moderate.", "see-also": "Chapters 3, 7, 8, 10, 11, 12, 14, 15" }, "skepticsBox": [ "Evolutionary psychiatry has a testability problem. The three stories about depression were fitted to observations after the fact, and such stories are cheap to build and expensive to test. The hunter-in-the-classroom evidence rests on one gene study, one online game and one natural experiment in diagnosis rates, and none of it shows ADHD traits helped most ancient foragers. The exercise trials cannot be blinded, so the size of the benefit is uncertain, though not its direction. The serotonin review drew published rebuttals of its methods, and neither side's argument bears on whether the drugs beat placebo. The stress-and-heart links are mostly observational, and the stress-to-disease effect in adults is moderate. Large, preregistered trials tracking depression or heart disease for years would show what breathing and mindfulness are worth." ], "verdicts": [ { "claim": "Chronic stress wears out your adrenal glands, a condition called adrenal fatigue, and saliva tests and adrenal supplements can fix it", "verdict": "False", "grade": "probable", "url": "https://www.spiralstaircase.com/verdicts/chronic-stress-wears-out-your-adrenal-glands-a" }, { "claim": "The physiological sigh, two inhales through the nose and a long exhale through the mouth, is the fastest proven way to calm down", "verdict": "A reasonable quick reset with thin evidence; \"fastest\" and \"proven\" are overstated", "grade": "emerging", "url": "https://www.spiralstaircase.com/verdicts/the-physiological-sigh-two-inhales-through-the-nose-and" }, { "claim": "Breathwork will fix your anxiety", "verdict": "Helps a little; not a substitute for therapy or medication", "grade": "probable", "url": "https://www.spiralstaircase.com/verdicts/breathwork-will-fix-your-anxiety" } ], "worksCited": 67 }, { "id": "14-wanting-loving-losing-meaning", "number": 14, "title": "Wanting, Loving, Losing, Meaning", "topic": "Addiction, love, grief and meaning: what the evidence says", "part": "The Social Animal", "url": "https://www.spiralstaircase.com/book/14-wanting-loving-losing-meaning", "startHere": [ { "action": "Invest in the quality of your closest relationship, and get couple therapy if it is in trouble", "grade": "probable", "grades": [ "probable", "strong" ], "scope": [ { "grade": "probable", "text": null }, { "grade": "strong", "text": null } ], "detail": "How: set a fixed, phone-free time together each week, even half an hour after the children are in bed, and when an argument turns hostile, stop and come back to it later. If the relationship is distressed, find a couple therapist, or start with a structured online program such as OurRelationship if cost or access is a barrier. Why: quality, not status, carries the health link, and couple therapy has large effects." }, { "action": "Take on a recurring role, about two hours a week", "grade": "probable", "grades": [ "probable" ], "scope": [ { "grade": "probable", "text": null } ], "detail": "How: a volunteering shift, a standing commitment to a person or a group that meets regularly and expects you, a project that would go undone without you. Put it on the calendar like a class. Why: purpose and regular volunteering are consistently linked to lower mortality, though no trial has shown they cause it." }, { "action": "If a substance or habit has a grip, change your surroundings, and ask about medicine alongside it", "grade": "probable", "grades": [ "probable", "strong" ], "scope": [ { "grade": "probable", "text": "for the setting" }, { "grade": "strong", "text": "for the alcohol medicines" } ], "detail": "How: take the supply out of the house, change the routes, places and company tied to use, and put something rewarding in the gap, ideally something with people in it. If you have been drinking heavily for a long time, talk to a doctor before you stop. If you drink too much, ask a doctor about acamprosate or naltrexone; for opioids, ask about methadone or buprenorphine. Your doctor sets the dose, and before starting naltrexone, tell your doctor about every medicine you use, especially opioid painkillers. Why: the veterans' surroundings changed and most stopped, and the medicines help many who need more than that; a new setting does not replace treatment for a moderate or severe disorder." }, { "action": "After a death, lean on people", "grade": "probable", "grades": [ "probable" ], "scope": [ { "grade": "probable", "text": null } ], "detail": "How: accept help with meals, errands and paperwork in the first weeks and months. If grief still dominates daily life six to twelve months on, ask for grief-specific therapy (●●●), such as complicated grief treatment. Why: most people adapt without treatment, and for those who do not, a targeted therapy works." } ], "thenIfYouWantMore": [], "mismatchCard": { "system": "The reward system (dopamine-driven wanting) and the attachment systems that bond, grieve and seek a role.", "what-it-expects": "Rewards that are scarce, variable and diluted; a partner and a small group met every day; losses mourned with others; a role the group depends on.", "what-it-gets": "Pure, cheap, constant drugs and betting on a phone, with close relationships, mourning and purpose left to arrange themselves.", "what-happens-in-the-gap": "Substance use disorders in about 15 percent of Americans aged twelve and over, just over half of them mild; a rise in mortality after bereavement, sharpest in the first months and in men; higher mortality with low purpose in cohorts.", "the-handrail": "Tend the closest relationship; keep a recurring role; change the setting and use the treatments that work; lean on people after a loss (●●○)", "strength-of-evidence": "●●○ The treatments for addiction, couples and prolonged grief rest on trials; the links from relationships, purpose and belonging to longer life rest on large but confounded cohorts.", "see-also": "Chapters 1, 5, 11, 12, 13, 15, 16" }, "skepticsBox": [ "Much of this chapter rests on observational evidence. The veterans were not randomized, and the few who entered treatment were probably the most severe, so the study cannot show that treatment is useless, only that setting mattered. The purpose, volunteering and religion findings share one weakness: illness lowers participation before death, and people who volunteer or attend were healthier to begin with. The health benefits of good relationships are small and correlational, and the sex trends rest on self-report. The harm from sports betting is not settled either: one small American study that followed bettors for two years found no clear change in problem gambling. The strongest evidence here is for the treatments, which all have trials. Open questions remain: whether addiction is best seen as a brain disease, a hijack or deep learning, and how much of the veterans' recovery would carry over to people who became addicted at home, among their own cues. If large cohorts that tracked purpose before illness found the link vanishing, the Meaning section would shrink to a matter of taste, and that would be worth knowing." ], "verdicts": [ { "claim": "A dopamine fast resets your brain", "verdict": "The name misreads the science, and the behavior can help", "grade": "emerging", "url": "https://www.spiralstaircase.com/verdicts/a-dopamine-fast-resets-your-brain" }, { "claim": "Rat Park proved addiction is about the cage, not the drug", "verdict": "Overstated", "grade": "emerging", "url": "https://www.spiralstaircase.com/verdicts/rat-park-proved-addiction-is-about-the-cage-not-the-drug" } ], "worksCited": 75 }, { "id": "15-womens-bodies-across-the-life-course", "number": 15, "title": "Women's Bodies Across the Life Course", "topic": "Women's health from periods to menopause: the evidence", "part": "The Life Course", "url": "https://www.spiralstaircase.com/book/15-womens-bodies-across-the-life-course", "startHere": [ { "action": "In the reproductive years, track your cycle as a vital sign", "grade": "probable", "grades": [ "probable" ], "scope": [ { "grade": "probable", "text": "for spotting problems early" }, { "grade": null, "text": "the wider vital-sign idea is expert opinion" } ], "detail": "How: note the first day of each period, how long it lasts and how heavy it is, in any calendar or app, and watch for change from your own pattern. Why: the cycle reports on energy, iron loss, hormones and, later, the start of the transition, for free." }, { "action": "In perimenopause, take your symptoms to a clinician, because effective treatments exist", "grade": "strong", "grades": [ "strong" ], "scope": [ { "grade": "strong", "text": null } ], "detail": "How: book an appointment for this alone, with a list: flushes, night sweats, sleep, mood, vaginal or urinary symptoms, and changes in bleeding. Ask about hormone therapy, including a patch or gel, and about the non-hormonal options. Why: hormones treat flushes best, and for healthy women under sixty or within ten years of menopause the balance is favorable." }, { "action": "At every stage, lift", "grade": "strong", "grades": [ "strong", "probable" ], "scope": [ { "grade": "strong", "text": "for strength" }, { "grade": "probable", "text": "for bone" } ], "detail": "How: two strength sessions a week of about thirty minutes. The home session in Chapter 4 needs only a chair, a wall and a loaded bag; add load until the last few repetitions feel hard. After fifty, or with low bone mass, work toward heavier lifts and impact training taught in person. Why: bone loss is fastest around the final period, lean mass falls across the transition, and supervised heavy lifting twice a week built spine bone in women with low bone mass, while walking alone does little." } ], "thenIfYouWantMore": [], "mismatchCard": { "system": "The female reproductive axis across a lifetime, from first period through pregnancy to the transition and the decades after it.", "what-it-expects": "A first period in the mid-teens, many pregnancies with long breastfeeding between them and about a hundred periods in a lifetime, food that matches effort, kin nearby, and a working body that carries loads through the transition.", "what-it-gets": "Earlier first periods, fewer and later births, short breastfeeding and about four hundred periods; energy deficits in some and surpluses in others; grandmothers far away; and a transition lived mostly sitting down.", "what-happens-in-the-gap": "More hormone-driven cancers and more iron lost; periods that stop from low energy; common conditions such as PCOS and endometriosis diagnosed late; symptoms of the transition endured instead of treated; bone and muscle lost fastest just as loading falls.", "the-handrail": "Track the cycle, take perimenopausal symptoms to a clinician, lift at every stage (●●○)", "strength-of-evidence": "●●○ The treatments for flushes, the contraception risks and the pregnancy heart flags rest on trials and large cohorts; the evolutionary accounts of menopause and PCOS, and the timing hypothesis, do not.", "see-also": "Chapters 4, 5, 8, 9, 11, 13, 16" }, "skepticsBox": [ "The chapter's frame rests on one village: Strassmann's lifetime counts are extrapolated from two years of hut records, and \"cycles\" stand in for hormone exposure. No one can rerun human evolution to test the grandmother hypothesis, and the Ngogo chimpanzees may be a well-fed exception. The timing hypothesis for hormone therapy could fall to a large trial that started women at fifty and counted heart attacks and deaths. The pooled breast cancer figures assume causation, and for estrogen alone they conflict with the trial. The FDA's relabeling reads old evidence differently; it adds none. The pill's link to mood is observational, the adult cycle as a vital sign is expert opinion, and the evolutionary account of PCOS is a hypothesis. The firm core is this: effective treatments for flushes exist, contraception's absolute risks are small, pregnancy complications flag later heart risk, and loaded exercise builds bone." ], "verdicts": [ { "claim": "Sync your workouts to your cycle: lift heavy in the first half, go easy in the second", "verdict": "Not supported", "grade": "probable", "url": "https://www.spiralstaircase.com/verdicts/sync-your-workouts-to-your-cycle-lift-heavy-in-the" }, { "claim": "Hormone therapy causes breast cancer", "verdict": "Partly true and badly overstated", "grade": "strong", "url": "https://www.spiralstaircase.com/verdicts/hormone-therapy-causes-breast-cancer" } ], "worksCited": 102 }, { "id": "16-aging-well", "number": 16, "title": "Aging Well", "topic": "Aging well: what the evidence says, and where to start", "part": "The Life Course", "url": "https://www.spiralstaircase.com/book/16-aging-well", "startHere": [ { "action": "Keep up the five things in Chapter 1", "grade": "strong", "grades": [ "strong" ], "scope": [ { "grade": "strong", "text": "for not smoking" }, { "grade": null, "text": "the rest are graded there" } ], "detail": "How: don't smoke, drink little or nothing, walk toward seven or eight thousand steps a day, cut the ultra-processed share of your food, keep a regular wake time, and see your three to five people. Why: on this book's reading, they act on six of the ten leading causes of death." }, { "action": "Get the screenings due for your age and sex", "grade": "strong", "grades": [ "strong" ], "scope": [ { "grade": "strong", "text": "as guideline recommendations" }, { "grade": null, "text": "PSA an individual choice" }, { "grade": null, "text": "skin checks unproven" } ], "detail": "How: go through the table above with your clinician once, put the due dates in a calendar, and set reminders for the repeats. Why: for most rows the Task Force judged that benefits outweigh harms for people at average risk." }, { "action": "Keep your strength and grip", "grade": "strong", "grades": [ "strong", "probable" ], "scope": [ { "grade": "strong", "text": "for strength" }, { "grade": "probable", "text": "for longer life" } ], "detail": "How: twice a week, about half an hour: sit-to-stands from a dining chair (a cushion raises the seat if your knee complains), push-ups against a wall or counter, rows with a band, and a heavy shopping bag carried in each hand (Chapters 1 and 4). Once or twice a year, count how many times you can stand up from a chair in thirty seconds without using your hands, and write it down; treat a poor score as a reason to train rather than a forecast. Why: strength falls faster than muscle bulk with age, and weakness predicts disability and earlier death." } ], "thenIfYouWantMore": [], "mismatchCard": { "system": "The whole body over a lifetime: the cells that age and occasionally turn cancerous, and the organs that fail at the end.", "what-it-expects": "Daily physical work, food that comes and goes, constant company and microbes, and death arriving mostly from outside, after a modal age in the seventies.", "what-it-gets": "Low physical load, constant food, tobacco and alcohol, and medicine that postpones death from diseases whose causes remain in place.", "what-happens-in-the-gap": "Longer lives with a wider strip of illness at the end; in the United States, the widest gap between lifespan and healthy lifespan of 183 countries studied.", "the-handrail": "The five things in Chapter 1, the screenings due for your age and sex, and kept strength (●●○).", "strength-of-evidence": "●●○ Screening rests on trials and quitting smoking on large, consistent cohorts; the links between strength, lifestyle and a shorter sick spell at the end come from cohorts and population data.", "see-also": "Chapters 1, 3, 4, 6, 7, 8, 10, 11, 14, 15" }, "skepticsBox": [ "The healthspan figures are modeled averages for whole countries, built on disability weights that reasonable people dispute, and part of the modern cause-of-death table is a byproduct of survival: people who no longer die at thirty of infection live long enough to develop, and be diagnosed with, cancer and dementia. Fries's compression hypothesis is still argued over. The Tsimane data are cross-sectional snapshots of a small, selected population, and one finding cuts against any tidy story: carriers of APOE4, the gene variant most linked to Alzheimer's in industrialized countries, had better-preserved thinking when their parasite load was high. Screening rests on randomized trials, but its benefits are counted per thousand people, and the PSA numbers could shift as MRI changes who gets biopsied. And the claim that six of ten leading causes are largely modifiable is this book's synthesis, an argument rather than a statistic." ], "verdicts": [ { "claim": "Every man over forty should be on testosterone", "verdict": "False", "grade": "strong", "url": "https://www.spiralstaircase.com/verdicts/every-man-over-forty-should-be-on-testosterone" }, { "claim": "An epigenetic age test tells you how fast you are aging", "verdict": "Not reliable for individuals", "grade": "probable", "url": "https://www.spiralstaircase.com/verdicts/an-epigenetic-age-test-tells-you-how-fast-you-are-aging" }, { "claim": "NAD+ boosters and other longevity supplements slow aging", "verdict": "Unsupported so far", "grade": "probable", "url": "https://www.spiralstaircase.com/verdicts/nad-boosters-and-other-longevity-supplements-slow-aging" } ], "worksCited": 103 } ] }