# Sleep Supplements

[The Research](https://boddy.app/research.md) / [Sleep](https://boddy.app/sleep.md) / [Excluded](https://boddy.app/sleep/excluded.md)  
Canonical: https://boddy.app/sleep/excluded/supplements  
Last reviewed: 2026-10-23

## What It Is

Melatonin, magnesium, valerian, ashwagandha, and similar over-the-counter sleep aids.

## Why It Matters

Melatonin is the best-studied of these and it does something for sleep: pooled across double-blind trials it shortens the time taken to fall asleep and adds sleep, and the effect may be larger in people who already sleep normally than in people with insomnia.[1] What it has not been shown to do is change any outcome that lasts. Three large cohorts that followed melatonin users for years found no link between taking it and later heart disease, stroke, or type 2 diabetes.[2] All-cause mortality, the outcome Boddy grades behaviors on, has not been measured in any peer-reviewed study of otherwise healthy people who take it, so the evidence is very uncertain about whether any of this reaches your lifespan.

Three things temper even the sleep finding. The synthesis reporting it detected publication bias on exactly the outcome melatonin is best known for, how fast you fall asleep, so that estimate is probably flattered.[1] Its models favored a larger dose taken a few hours before the desired bedtime, which is not how most people take it.[1] And the randomized trials that found no rise in serious harms did find more drowsiness, headache, and dizziness.[3] Meanwhile the body that writes the guideline for chronic insomnia advises clinicians not to use melatonin, valerian, or tryptophan for it,[4] and a large comparison of insomnia medications placed melatonin among the drugs showing no material benefit.[5] The rest of the shelf is thinner: magnesium rests on trials its own reviewers call substandard,[6] the L-theanine gains show up in how people rate their own sleep but not in sleep as measured,[7] and the ashwagandha trials are few and short, leaving long-term safety unknown.[8]

If you already take something and feel it helps you sleep, this entry is not telling you to stop. It asks whether these do anything that lasts, and the evidence on that is very uncertain, so this is not a lever we can put a number on and ask every reader to track. It is not a safety review either: long-term safety has not been established for most of them, so check with a clinician before taking one for months, especially if you take other medicines.

## GRADE

- Certainty: Very Low
- Magnitude: Unknown

## References

1. Cruz-Sanabria, F. et al. (2024). Optimizing the Time and Dose of Melatonin as a Sleep-Promoting Drug: A Systematic Review of Randomized Controlled Trials and Dose-Response Meta-Analysis. Journal of Pineal Research. https://doi.org/10.1111/jpi.12985
2. Li, Y. et al. (2024). Use of melatonin supplements and risk of type 2 diabetes and cardiovascular diseases in the USA: insights from three prospective cohort studies. The Lancet Diabetes & Endocrinology. https://doi.org/10.1016/S2213-8587(24)00096-2
3. Menczel Schrire, Z. et al. (2021). Safety of higher doses of melatonin in adults: A systematic review and meta-analysis. Journal of Pineal Research. https://doi.org/10.1111/jpi.12782
4. Sateia, M.J. et al. (2017). Clinical Practice Guideline for the Pharmacologic Treatment of Chronic Insomnia in Adults: An American Academy of Sleep Medicine Clinical Practice Guideline. Journal of Clinical Sleep Medicine. https://doi.org/10.5664/jcsm.6470
5. De Crescenzo, F. et al. (2022). Comparative effects of pharmacological interventions for the acute and long-term management of insomnia disorder in adults: a systematic review and network meta-analysis. The Lancet. https://doi.org/10.1016/S0140-6736(22)00878-9
6. Mah, J., Pitre, T. (2021). Oral magnesium supplementation for insomnia in older adults: a systematic review and meta-analysis. BMC Complementary Medicine and Therapies. https://doi.org/10.1186/s12906-021-03297-z
7. Bulman, A. et al. (2025). The effects of L-theanine consumption on sleep outcomes: A systematic review and meta-analysis. Sleep Medicine Reviews. https://doi.org/10.1016/j.smrv.2025.102076
8. Cheah, K.L. et al. (2021). Effect of Ashwagandha (Withania somnifera) extract on sleep: A systematic review and meta-analysis. PLoS One. https://doi.org/10.1371/journal.pone.0257843