Sleep & Circadian Supplements
Magnesium, Glycine, Theanine, Apigenin & More
Evidence grade 2 of 5, Thin. Read how the Atlas grades evidence.
18 human trials, about 120 studies, >3,000 participants. The written rationale for this grade is still being prepared.
- FDA
- Supplements (vary)
- WADA
- Not prohibited
Reference only. Not medical advice.
What can go wrong
Effects across this category are modest and the evidence base is preliminary-to-mixed, not strong. Ashwagandha carries a documented liver-injury signal (NIH LiverTox likelihood score B), typically appearing 2 to 12 weeks into use, and should be avoided by people with existing liver disease. Because US supplements are not approved by the FDA before sale, label content is not independently verified, and independent testing repeatedly finds actual doses far from those stated, which matters most for melatonin. Proprietary blends frequently underdose the evidence-backed ingredients while charging a premium. Supplements are adjuncts, not substitutes for consistent light exposure and sleep timing. These products are not appropriate for children, during pregnancy or breastfeeding, or for people managing a diagnosed sleep, mood, or medical condition without first consulting a qualified healthcare provider, who should also review interactions with any existing medications.
A practical, evidence-honest map of sleep and circadian supplements, sorted by what the trials actually show rather than by what the strongest member promises. The genuinely better-supported agents have modest, real, and still-imperfect data: ashwagandha (cortisol and sleep reduction in stressed or insomniac users, though with a flagged liver-injury signal), magnesium, and L-theanine 200mg. Glycine and apigenin/chamomile remain preliminary, often resting on very small or non-significant trials. Timed low-dose melatonin is the firmest circadian tool and is covered separately. Two cross-cutting cautions define the category: in the United States supplements are not approved by the FDA before sale, and independent testing repeatedly finds label content that does not match the bottle. The recurring scientific message, that consistent light and timing outperform any pill, is the part the marketing most often omits.
Magnesium, glycine, and theanine have real (modest) data. Most sleep stacks oversell.
What people take it for
These are the reasons people give for taking it. They are not effects it has been shown to have.
What people get wrong
Often saidA sleep-supplement stack fixes poor sleep
ActuallyThe better-evidenced agents (ashwagandha, magnesium, L-theanine) show modest effects in trials the authors themselves rate low-to-moderate quality, and they work best alongside light and timing fixes. The magnesium-for-insomnia meta-analysis (Mah & Pitre 2021, 3 RCTs / 151 adults) was explicitly graded low-to-very-low quality with moderate-to-high risk of bias.
Often saidNatural means safe, so dose and source do not matter
ActuallyAshwagandha is flagged by NIH LiverTox at likelihood score B for clinically apparent liver injury, with cases of cholestatic injury and rare transplant or fatal outcomes, and its use is advised against in people with cirrhosis or advanced liver disease. Natural origin is not a safety guarantee.
Often saidThe bottle contains what the label says
ActuallyCohen et al. (JAMA, 2023) found 22 of 25 US melatonin gummy products (88%) inaccurately labeled, with actual melatonin ranging from 74% to 347% of the stated amount and one product containing none. US supplements are not FDA-approved before sale, so label content is not independently verified at market entry.
Often saidThe proven ingredient is the one doing the work in the blend
ActuallyMany proprietary stacks underdose the evidence-backed components relative to the doses used in trials (for example ashwagandha sleep benefits concentrated at 600mg/day or more), so the named ingredient may be present at a fraction of the studied amount.
Who profits, and who pushes back
Pieter A. Cohen, MD
In the analyzed melatonin gummies, the actual quantity ranged from 74% to 347% of the labeled quantity, and 22 of 25 products were inaccurately labeled, so children consuming them as directed could be exposed to many times the intended dose.
NIH LiverTox (NIDDK), National Library of Medicine
Ashwagandha is assigned a likelihood score of B, a likely cause of clinically apparent liver injury, and its use should be avoided in patients with cirrhosis or advanced chronic liver disease.
Mah & Pitre (magnesium-insomnia meta-analysis authors)
All trials were at moderate-to-high risk of bias and outcomes were supported by low to very low quality of evidence.
Dr. Andrew Huberman
Popularized a magnesium-threonate/glycine/theanine/apigenin stack; some via his Momentous line (commercial). Mechanism-based but verify dosing.
Sleep-supplement industry
Sells this. Has a commercial interest in a product sold as this compound, as of July 2026.
Sells proprietary "sleep" blends, often underdosing the evidence-backed components; strong commercial interest.
Where the research comes from
| Place | Share of published research |
|---|---|
| USA | 46% |
| Europe | 28% |
| Other | 26% |
Research published from: Global.
How we got here
Sleep-promoting plants and minerals long predate the supplement aisle. Ashwagandha (Withania somnifera) has been used as a rasayana tonic in Ayurvedic practice on the Indian subcontinent for more than two millennia, valued for calming and restorative effects. Chamomile, the source of apigenin, was used as a soothing infusion across ancient Egypt, the eastern Mediterranean, and West Asia. Valerian appears in Greek and South Asian medical texts. The isolated-compound, single-pill framing is recent and Western-commercial: glycine sleep work emerged from Japanese researchers in the 2000s, magnesium and L-theanine trials accumulated through the 2010s, and a podcast and influencer-driven market of proprietary stacks proliferated in the 2010s and 2020s, frequently underdosing the very ingredients whose names sold the product. The traditional preparations were whole-plant and ritualized around evening and rest; the modern market abstracted single molecules and wrapped them in claims the evidence had not yet earned.
- pre-1000 BCEAshwagandha used as a rasayana tonic in Ayurvedic practice on the Indian subcontinent
- ancient eraChamomile (apigenin source) used as a calming infusion across Egypt, the Mediterranean, and West Asia
- 1994US DSHEA defines supplements as foods, exempting them from pre-market FDA approval for safety or efficacy
- 2007Standardized chamomile extract RCT in primary insomnia reports only a non-significant trend for sleep
- 2012Bannai and colleagues publish small glycine (3g) crossover trials on subjective sleep and daytime performance (n=7)
- 2019Hidese et al. report L-theanine 200mg improving PSQI sleep and anxiety scores in a placebo-controlled RCT
- 2021Mah & Pitre magnesium-for-insomnia meta-analysis (3 RCTs, n=151) and Cheah et al. ashwagandha-sleep meta-analysis (5 RCTs, n=400) both report modest effects with low-to-moderate evidence quality
- 2023Cohen et al. JAMA research letter finds 88% of US melatonin gummies inaccurately labeled (74-347% of stated dose)
- 2020sNIH LiverTox lists ashwagandha at likelihood score B for clinically apparent liver injury as case reports accumulate
At a glance
- Best evidence
- Mg glycinate, glycine, L-theanine
- Cortisol
- Ashwagandha (stressed users)
- Overhyped
- Most proprietary "sleep stacks"
- Note
- Timing/behavior beat pills
What this entry does not yet cover
What follows is unfinished work on our side, not a finding about Sleep & Circadian Supplements. A short entry is not a safe entry.
- Cost and market. We have not documented what it sells for or who sells it.
- Supply chain. We have not mapped where it is made.
- Who uses it. We have not documented the user groups.
- What could change. No forward-looking summary yet.
- How it compares. We have not set it against the alternatives.
- Children and teenagers. We have not checked what is known about younger people.
Sources
Magnesium reduces sleep onset latency by ~17 min across 3 RCTs in older adults, but evidence is low-to-very-low quality with moderate-to-high risk of bias
Magnesium bisglycinate produced only a small reduction in insomnia severity (Cohen d=0.2) in a recent placebo-controlled RCT
Glycine 3g before bed improved subjective fatigue and psychomotor performance during sleep restriction, in a very small (n=7) crossover trial
L-theanine 200mg/day for 4 weeks reduced PSQI sleep and anxiety scores in a placebo-controlled RCT
Ashwagandha extract had a small but significant effect on overall sleep (SMD -0.59) across 5 RCTs / 400 participants, with stronger effects at >=600mg/day, >=8 weeks, and in diagnosed insomnia, but low-to-moderate quality and high heterogeneity (I-squared=62%)
Cheah et al., Effect of Ashwagandha extract on sleep, systematic review and meta-analysis (PLOS One)
Ashwagandha is assigned NIH LiverTox likelihood score B (likely cause) for clinically apparent liver injury; cholestatic/mixed pattern, rare transplant or fatal cases, avoid in cirrhosis/advanced liver disease
NIH LiverTox (NIDDK / National Library of Medicine), Ashwagandha monograph
Apigenin/chamomile sleep trials are preliminary and often non-significant; clinical effects derive from whole chamomile preparations, not isolated apigenin
Apigenin: a natural molecule at the intersection of sleep and aging (Frontiers in Nutrition)
Timed low-dose melatonin (0.2-0.5mg given ~2-3h before DLMO) produces circadian phase advances; appropriately timed melatonin is effective for delayed sleep-wake phase disorder
88% (22 of 25) of US melatonin gummy products were inaccurately labeled, actual content 74-347% of label, one product had no detectable melatonin; serotonin not detected in this sample
Cohen et al., Quantity of Melatonin and CBD in Melatonin Gummies Sold in the US (JAMA, 2023)
The FDA does not approve dietary supplements or their labels before sale; structure/function claims require post-market notification, substantiation, and a not-evaluated-by-FDA disclaimer
US FDA, Questions and Answers on Dietary Supplements; Structure/Function Claims guidance