Glycine
Sleep & Recovery · Amino acid / NMDA co-agonist
Tier B-
Bottom line
Read Off Label grades Glycine as B- (6.2/10) based on weak-moderate evidence, low-moderate benefit magnitude, and a low-risk safety profile.
Ajinomoto-era Japanese research tradition demonstrated modest but consistent subjective and polysomnographic sleep quality improvements at 3 g (faster sleep onset; improved sleep efficiency; reduced next-day fatigue).
Typical use: 3 g PO 30-60 min before bed — OTC.
What this is
Ajinomoto-era Japanese research tradition demonstrated modest but consistent subjective and polysomnographic sleep quality improvements at 3 g (faster sleep onset; improved sleep efficiency; reduced next-day fatigue). Razak 2023 systematic review (GeroScience) covered 11 physiological systems and found nervous-system endpoints had the strongest evidence overall but flagged small samples and bias risk. Hannan 2024 Nutrients update review (PMID 39453231) re-confirmed sleep/recovery role. Cheap; sweet taste makes it easy to take; no tolerance documented. Distinct use case from the new Longevity entry (higher daily doses to address age-related shortfall) and from GlyNAC (paired with NAC for glutathione).
Mechanism
Simple amino acid; NMDA receptor co-agonist; inhibitory at spinal cord via strychnine-sensitive glycine receptors; reduces core body temperature via peripheral vasodilation aiding sleep onset; modest sleep quality improvement in Japanese RCTs
Dose & route
3 g PO 30-60 min before bed
Citations
- https://pubmed.ncbi.nlm.nih.gov/17341027/
- https://pubmed.ncbi.nlm.nih.gov/22293292/
- https://pmc.ncbi.nlm.nih.gov/articles/PMC7589578/
- https://link.springer.com/article/10.1007/s11357-023-00970-8
- https://pubmed.ncbi.nlm.nih.gov/39453231/
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Common questions
- Does Glycine work?
- Read Off Label rates the evidence for Glycine as Weak-Moderate and the benefit magnitude as low-moderate, producing an overall grade of B- (6.2/10). Ajinomoto-era Japanese research tradition demonstrated modest but consistent subjective and polysomnographic sleep quality improvements at 3 g (faster sleep onset; improved sleep efficiency; reduced next-day fatigue).
- Is Glycine safe?
- Glycine has a low risk profile in published human data. Legal status: OTC. This is not medical advice — see the disclaimer.
- What is the typical dose for Glycine?
- 3 g PO 30-60 min before bed
- How does Glycine work?
- Simple amino acid; NMDA receptor co-agonist; inhibitory at spinal cord via strychnine-sensitive glycine receptors; reduces core body temperature via peripheral vasodilation aiding sleep onset; modest sleep quality improvement in Japanese RCTs
This is an independent synthesis of published research by a non-clinician. Scores are opinions supported by citations, not prescriptions. See the full disclaimer and methodology for how this score was produced and what it does and doesn't mean.