Amino Acid
L-Glycine
Also known as: Glycine, L-α-Aminoacetic acid, Aminoacetic acid
A simple, non-essential amino acid with documented sleep-promoting properties through thermoregulation and GABA receptor modulation. Evidence supports its use for improving sleep latency and quality.
Daily target & upper limit
3 g / dayL-Glycine has an established daily reference intake. See best forms, label synonyms, upper-limit warnings, and top-scoring supplements:
L-Glycine dosage reference →Primary uses
- Sleep onset improvement
- Sleep quality
- Relaxation
- Collagen synthesis
How it works
- Glycine receptor agonist (inhibitory neurotransmitter)
- Promotes vasodilation and heat dissipation (core temperature reduction)
- Indirect GABA potentiation
- CNS relaxation
Dosage
- Typical range
- 3-10 g daily (most studies use 3g)
- Timing
- 30-60 minutes before bed
- With food
- Can take with or without food
- Duration
- Safe for long-term daily use; benefits may increase with consistent use over 2+ weeks
- Special populations
- Generally well-tolerated across populations
Forms
- L-Glycine powder or capsules· 70/100
Safety
Common side effects
- Well-tolerated; minimal side effects at 3-10g doses
- Mild GI effects possible at very high doses
Contraindications
- None established at typical doses
Products containing L-Glycine
Top-scoring supplements in our catalog that list L-Glycine on the label. Each product is graded on Formulate's ingredient-level rubric — dose accuracy, form, transparency, and third-party testing.
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Known interactions
Evidence notes
Good RCT evidence (Japanese trials) showing 3g glycine reduces sleep latency and improves subjective sleep quality; mechanism well-characterized.
Grade B: Some human trials support key claims; further confirmation needed.
Cited research for L-Glycine
Clinical studies referenced across Formulate guides that mention l-glycine. Each links to the full study page with PubMed source + the guides that cite it.
- Kawai N, Sakai N, Okuro M, et al. (2015)Neuropsychopharmacology
The sleep-promoting and hypothermic effects of glycine are mediated by NMDA receptors in the suprachiasmatic nucleus
- Bannai and Kawai (2012)Journal of Pharmacological Sciences
New therapeutic strategy for amino acid medicine: glycine improves the quality of sleep
- Yamadera W, Inagawa K, Chiba S, et al. (2007)Sleep and Biological Rhythms
Glycine ingestion improves subjective sleep quality in human volunteers
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