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Research Guide

Supplements for Sleep

Dozens of supplements are marketed for sleep. We reviewed the clinical trial evidence for 11 of the most studied to help you understand what the research actually supports.

11 supplements reviewed 15 studies cited Last reviewed: March 2026

Evidence Summary

The table below ranks each supplement by the strength of its clinical evidence for sleep outcomes. "Evidence strength" reflects the quantity, quality, and consistency of randomized controlled trials and meta-analyses — not our opinion on whether it "works."

Supplement Evidence Key Finding Research Dosages
Melatonin Strong Reduces sleep onset latency by ~7 min, increases total sleep by ~8 min[1][2] 0.5–10 mg/day
Magnesium Moderate May reduce sleep onset latency by ~17 min in older adults[3] 225–729 mg/day
Ashwagandha Moderate Significant improvement in overall sleep quality (SMD -0.59)[5] 120–600 mg/day
L-Theanine Moderate Improves subjective sleep quality across 19 RCTs[7] 200–400 mg/day
Valerian Root Moderate 60-study review suggests it safely promotes sleep, but extract variability affects results[8] 300–900 mg/day
Glycine Moderate 3 g before bed reduces fatigue and improves next-day alertness[9] 3 g/day
Zinc Limited Majority of 8 RCTs show improvement in sleep quality[11] 10–73 mg/day
Omega-3 Limited Significantly higher sleep efficiency vs. control in 8-RCT meta-analysis[12] 0.6–4 g/day
Collagen Limited Single RCT: 15 g before bed reduced nighttime awakenings[13] 10–15 g/day
Lion's Mane Insufficient Open-label study showed decreased sleep disorders alongside mood improvements[14] 0.5–3 g/day
Creatine Insufficient Does not improve sleep directly; may mitigate cognitive decline from sleep deprivation[15] 3–5 g/day

Strong & Moderate Evidence

Melatonin

Melatonin is the most extensively studied sleep supplement. A 2013 meta-analysis of 19 RCTs (1,683 participants) found it reduced sleep onset latency by approximately 7 minutes and increased total sleep time by about 8 minutes.[2] A more recent 2024 dose-response meta-analysis identified an optimal dose of around 4 mg taken 3 hours before bedtime, with diminishing returns at higher doses.[1]

While these effects are statistically significant, the clinical significance of a 7-minute improvement is debatable. Melatonin appears most beneficial for circadian rhythm disorders, jet lag, and delayed sleep phase — situations where the body's internal clock is misaligned.

Magnesium

A 2021 meta-analysis of 3 RCTs found magnesium reduced sleep onset latency by 17.36 minutes in older adults, though the evidence quality was rated low-to-very-low.[3] A broader 2024 systematic review found that 5 of 8 studies measuring sleep outcomes reported improvements, with benefits most pronounced in those with low baseline magnesium status.[4] Notably, approximately 50% of the US population consumes less than the estimated average requirement for magnesium.

Read our full deep dive: Magnesium for Sleep →

Ashwagandha

A 2021 meta-analysis of 5 RCTs (400 participants) found ashwagandha had a significant overall effect on sleep quality (SMD -0.59).[5] A 2024 review confirmed these findings and added that ashwagandha also reduced sleep onset latency, improved total sleep time, and enhanced sleep efficiency.[6] Benefits were greater with doses of 600 mg/day or more, treatment durations of 8+ weeks, and in individuals with diagnosed insomnia rather than healthy sleepers.

L-Theanine

A 2025 meta-analysis of 19 RCTs (897 participants) found L-theanine — an amino acid found naturally in tea — improved subjective sleep quality (SMD 0.43, p=0.03), reduced daytime dysfunction (SMD 0.33, p<0.001), and modestly decreased sleep onset latency.[7] L-theanine promotes alpha brain wave activity, which is associated with a state of relaxed alertness and may facilitate the transition to sleep.

Valerian Root

A comprehensive 2020 systematic review analyzed 60 studies (6,894 participants) and concluded that valerian is a safe herb that promotes sleep.[8] However, results are inconsistent, likely due to variability in extract preparation and quality. Studies using whole root or rhizome preparations showed more reliable results than standardized extracts. No severe adverse events were reported across ages 7–80.

Glycine

Taking 3 g of glycine before bed reduced subjective fatigue and improved next-day reaction times in sleep-restricted volunteers.[9] A 2024 systematic review of 52 human studies confirmed sleep quality improvements but noted small sample sizes and high risk of bias across the literature.[10] Glycine works by modulating core body temperature through NMDA receptors in the suprachiasmatic nucleus — a mechanism distinct from most other sleep supplements.

Limited & Emerging Evidence

Zinc

A 2024 systematic review of 8 RCTs found that the majority of studies showed significant improvement in sleep quality with zinc supplementation at doses of 10–73 mg/day over 4–48 weeks.[11] However, no significant effect was observed on diagnosed sleep disorders specifically. More trials are needed, particularly in zinc-deficient populations where benefits may be most relevant.

Omega-3 Fatty Acids

A 2024 meta-analysis of 8 RCTs found significantly higher sleep efficiency in the omega-3 group compared to control, along with improvements in subjective sleep quality.[12] However, no significant effects were found for sleep latency or total sleep duration. The mechanism may involve omega-3's role in serotonin metabolism and anti-inflammatory effects that reduce sleep-disrupting pain.

Collagen

A single crossover RCT of 13 physically active males found that 15 g of collagen peptides before bed reduced nighttime awakenings (21 vs. 29 counts, p=0.028) and improved next-day cognitive function, but did not affect sleep architecture.[13] Collagen's sleep benefit likely derives from its glycine content — approximately 33% of collagen is glycine, so a 15 g dose provides roughly 5 g of glycine, exceeding the 3 g threshold shown effective in glycine-specific trials.

Insufficient Evidence

Lion's Mane

An 8-week open-label study in overweight adults found decreased sleep disorders alongside mood improvements and increased pro-BDNF levels.[14] However, without a placebo control group, these results cannot be attributed to lion's mane specifically. No placebo-controlled RCTs targeting sleep as a primary outcome have been published.

Creatine

Creatine does not appear to improve sleep quality directly. However, a 2024 study found that a single high dose (0.35 g/kg) partially reversed cognitive decline caused by 21 hours of sleep deprivation by maintaining brain energy metabolism.[15] This makes creatine potentially relevant for mitigating the effects of poor sleep, rather than improving sleep itself.

What to Consider

Frequently Asked Questions

What is the most researched supplement for sleep?

Melatonin is the most extensively studied, with multiple meta-analyses encompassing thousands of participants. It has the strongest evidence for reducing sleep onset latency, though the absolute effect size (about 7 minutes) is modest. Research suggests an optimal dose of around 4 mg taken 3 hours before bed.[1]

Does magnesium help with sleep?

The evidence is moderate. A meta-analysis found it reduced sleep onset latency by about 17 minutes in older adults, and a systematic review found improvements in 5 of 8 sleep studies. Benefits appear most pronounced in those with low magnesium status. Read our full analysis →

Is ashwagandha good for sleep?

A meta-analysis of 5 RCTs found significant improvements in sleep quality. The effect was stronger with doses of 600+ mg/day, duration of 8+ weeks, and in those with diagnosed insomnia. It appears to work partly through anxiety reduction.[5]

Are sleep supplements safe?

Most supplements reviewed here have favorable safety profiles at standard doses. However, they can interact with medications — particularly sedatives, blood thinners, and blood pressure drugs. Melatonin may cause daytime drowsiness. Magnesium at high supplemental doses can cause GI distress. Always consult a healthcare provider before starting any supplement, especially if you take medications or have underlying conditions.

Medical Disclaimer: This guide is for informational purposes only and does not constitute medical advice. Always consult a qualified healthcare provider before starting any supplement regimen. SafeSupps does not recommend specific supplements — we present the research so you can make informed decisions.

References

  1. Cruz-Sanabria F, et al. "Optimizing the Time and Dose of Melatonin as a Sleep-Promoting Drug: A Systematic Review of Randomized Controlled Trials and Dose-Response Meta-Analysis." J Pineal Res. 2024;76(5):e12985. PubMed
  2. Ferracioli-Oda E, Qawasmi A, Bloch MH. "Meta-analysis: melatonin for the treatment of primary sleep disorders." PLoS One. 2013;8(5):e63773. PubMed
  3. Mah J, Pitre T. "Oral magnesium supplementation for insomnia in older adults: a Systematic Review & Meta-Analysis." BMC Complement Med Ther. 2021;21(1):125. PubMed
  4. Rawji A, et al. "Examining the Effects of Supplemental Magnesium on Self-Reported Anxiety and Sleep Quality: A Systematic Review." Cureus. 2024;16(4):e59317. PubMed
  5. Cheah KL, et al. "Effect of Ashwagandha (Withania somnifera) extract on sleep: A systematic review and meta-analysis." PLoS One. 2021;16(9):e0257843. PubMed
  6. Fatima K, et al. "Safety and efficacy of Withania somnifera for anxiety and insomnia: Systematic review and meta-analysis." Hum Psychopharmacol. 2024;39(6):e2911. PubMed
  7. Bulman A, et al. "The effects of L-theanine consumption on sleep outcomes: A systematic review and meta-analysis." Sleep Med Rev. 2025;81:102076. PubMed
  8. Shinjyo N, Waddell G, Green J. "Valerian Root in Treating Sleep Problems and Associated Disorders — A Systematic Review and Meta-Analysis." J Evid Based Integr Med. 2020;25:2515690X20967323. PubMed
  9. Bannai M, et al. "The effects of glycine on subjective daytime performance in partially sleep-restricted healthy volunteers." Front Neurol. 2012;3:61. PubMed
  10. Soh J, et al. "The effect of glycine administration on the characteristics of physiological systems in human adults: A systematic review." Geroscience. 2024;46:219-239. PubMed
  11. Jazinaki MS, et al. "Effects of zinc supplementation on sleep quality in humans: A systematic review of randomized controlled trials." Health Sci Rep. 2024;7(10):e70019. PubMed
  12. Shimizu K, et al. "Effect of omega-3 fatty acids on sleep: a systematic review and meta-analysis of randomized controlled trials." J Clin Biochem Nutr. 2024;75(3):204-212. PubMed
  13. Thomas C, et al. "Collagen peptide supplementation before bedtime reduces sleep fragmentation and improves cognitive function in physically active males with sleep complaints." Eur J Nutr. 2024;63(1):323-335. PubMed
  14. Vigna L, et al. "Hericium erinaceus Improves Mood and Sleep Disorders in Patients Affected by Overweight or Obesity." Evid Based Complement Alternat Med. 2019;2019:7861297. PubMed
  15. Gordji-Nejad A, et al. "Single dose creatine improves cognitive performance and induces changes in cerebral high energy phosphates during sleep deprivation." Sci Rep. 2024;14(1):4937. PubMed

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