What you've heard: Tart cherry juice and magnesium will fix your sleep
Do tart cherry juice and magnesium help you sleep?
Unproven. The juice adds sugar, and magnesium is a long shot, not a treatment. Evidence grade: Emerging.
Published Updated
The "What you've heard" box in Chapter 8
Unproven
Unproven. The juice adds sugar, and magnesium is a long shot, not a treatment.
The evidence
Tart cherries contain melatonin, but far less than a low-dose pill. The four trials were small and short: two found gains on some measures, one a modest effect on night waking, and the largest, which used capsules, found nothing. A recent review called the evidence limited. Magnesium has more trials and a similar story. A newer review of randomized trials rated the evidence low to very low certainty and did not support magnesium as a routine treatment for insomnia, though it may help a little in some people.15 Check with a clinician before taking magnesium if you have kidney disease or take other medicines.
Where the book tests it
Related claims
- Is mouth taping safe, and does it work?Unsupported, with a safety catch.Evidence grade: Emerging. Early, small, animal-only, or actively contested.
- Is sunscreen bad for you?Against: the one trial runs the other way.Evidence grade: Probable. Good observational evidence with a plausible mechanism, or small or few trials.
- Do blue light glasses work for sleep?Mostly unsupported; skip the glasses unless a clinician suggests them for a specific sleep problem.Evidence grade: Strong. Multiple randomized controlled trials, or consistent large cohort studies with a well-understood mechanism.
- Does ten minutes of morning sunlight set your body clock?Right direction, invented number.Evidence grade: Probable. Good observational evidence with a plausible mechanism, or small or few trials.
- Should you wait 90 minutes after waking for coffee?Untested, and the reasoning looks backward.Evidence grade: Emerging. Early, small, animal-only, or actively contested.
- Can NSDR or yoga nidra replace lost sleep?A pleasant way to rest, not a substitute for sleep.Evidence grade: Emerging. Early, small, animal-only, or actively contested.
Sources
The "What you've heard" box in Chapter 8
- 15.Burkhardt, S., Tan, D.X., Manchester, L.C., Hardeland, R., et al. (2001). "Detection and quantification of the antioxidant melatonin in Montmorency and Balaton tart cherries (Prunus cerasus)." Journal of Agricultural and Food Chemistry, 49(10), 4898-4902. https://doi.org/10.1021/jf010321+ ; Barforoush, F., Ebrahimi, S., Abdar, M.K., Khademi, S., et al. (2025). "The effect of tart cherry on sleep quality and sleep disorders: a systematic review." Food Science & Nutrition, 13(9), e70923. https://doi.org/10.1002/fsn3.70923 ; Tucker, R.M., Kim, N., Gurzell, E., Mathi, S., et al. (2024). "Commonly used dose of Montmorency tart cherry powder does not improve sleep or inflammation outcomes in individuals with overweight or obesity." Nutrients, 16(23), 4125. https://doi.org/10.3390/nu16234125 ; Lopresti, A.L., Smith, S.J., and Drummond, P.D. (2026). "Magnesium supplementation for sleep in adults: a systematic review of randomized controlled trials." Journal of Dietary Supplements, 23(5), 553-581. https://doi.org/10.1080/19390211.2026.2719670 (12 randomized trials.) ; Pigeon, W.R., Carr, M., Gorman, C., and Perlis, M.L. (2010). "Effects of a tart cherry juice beverage on the sleep of older adults with insomnia: a pilot study." Journal of Medicinal Food, 13(3), 579-583. https://doi.org/10.1089/jmf.2009.0096 ; Howatson, G., Bell, P.G., Tallent, J., Middleton, B., et al. (2012). "Effect of tart cherry juice (Prunus cerasus) on melatonin levels and enhanced sleep quality." European Journal of Nutrition, 51(8), 909-916. https://doi.org/10.1007/s00394-011-0263-7 ; Losso, J.N., Finley, J.W., Karki, N., Liu, A.G., et al. (2018). "Pilot study of the tart cherry juice for the treatment of insomnia and investigation of mechanisms." American Journal of Therapeutics, 25(2), e194-e201. https://doi.org/10.1097/MJT.0000000000000584 (Each tart cherry trial had at most a few dozen participants and lasted a week or two.)
Note numbers are those of Chapter 8, Sleep.
This verdict is one of the "What you've heard" boxes in Chapter 8, Sleep, where the book tests the claims people repeat against the studies behind them. The grade rates the evidence behind the verdict, by the book's stated method.
Educational content, not medical advice. Disclaimer.