Glycine reduces sleep latency in human RCTs
Glycine (3g before bed) significantly reduces sleep onset latency and improves subjective sleep quality in healthy adults. Evidence from 3 human RCTs shows consistent effects, with the mechanism involving NMDA receptor modulation and thermoregulation.
This article is automatically generated from the structured evidence profile behind the claim above. Scores reflect the quality and quantity of available research, not clinical advice.
Glycine reduces sleep latency in human RCTs The current body of evidence comprises 3 studyies, including 3 randomized controlled trials. EvidenceHub rates the overall confidence at 91/100 (high).
The Claim
Glycine reduces sleep latency in human RCTs
This conclusion is most relevant to: Healthy adults, Adults with mild sleep complaints.
How It Works
The proposed biological pathway:
- ▸Glycine
- ▸NMDA receptor modulation
- ▸Vasodilation & thermoregulation
- ▸Core body temperature drop
- ▸Sleep onset latency reduction
Who Might Benefit
Evidence fit by population:
- ▸Healthy adults
- ▸Adults with mild sleep complaints
Recommended Dose
3g
Limitations & Caveats
Important context when interpreting this evidence:
- ▸Small sample sizes (7-18 participants per study)
- ▸Short duration (2-4 nights per study)
- ▸No large-scale multicenter trials
- ▸Limited data on chronic use beyond 4 nights
Frequently Asked Questions
Does glycine work immediately for sleep?▼
Yes. Human RCTs show glycine reduces sleep latency on the first night of use. Effects do not appear to require accumulation.
Is glycine safe for long-term use?▼
Glycine is generally recognized as safe (GRAS). Studies up to 4 nights show no adverse effects, but long-term data beyond several weeks is limited.
How does glycine compare to melatonin?▼
Glycine primarily reduces sleep onset latency via thermoregulation, while melatonin shifts circadian timing. They work through different pathways and could be complementary.
What is the optimal dose of glycine for sleep?▼
3g taken 30-60 minutes before bed is the dose used in all positive human trials. Lower doses (2g) show mild effects; higher doses (5g) show no additional benefit.
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Glycine improves overall sleep quality and reduces daytime sleepiness
Beyond reducing sleep latency, glycine (3g before bed) improves PSG-measured sleep quality including increased REM sleep and reduced nocturnal awakenings. Daytime sleepiness and fatigue are also significantly reduced the following morning.