amino acid · for poor sleep quality
Glycine
Lowers your body temperature slightly, which is one of the signals that deepens sleep.
Say that in clinical terms
Glycine enhances slow-wave (deep) sleep by lowering core body temperature through peripheral vasodilation. It also modulates NMDA receptors and increases serotonin in sleep-regulating brain regions, improving overall sleep architecture.
How strong is the research?
1 paper read, 1 supporting.
Who was studied: Rats. The cited paper has no human subjects in it.
How much to take
daily, 1 hour before bed
3000 mg
Well-studied dose of 3g before bed. Improves subjective sleep quality and next-day alertness.
Before you take it
- No NIH ODS or IOM/NAM Tolerable Upper Intake Level (UL) has been established for glycine; it is absent from all NIH ODS fact sheets.
- FDA includes glycine on its GRAS (Generally Recognized as Safe) list for food use. Doses up to 90 g/day have been administered in psychiatric research trials without serious adverse events; GI discomfort (nausea) is the most commonly reported side effect at high doses.
- A pharmacodynamic interaction between supplemental glycine and clozapine (antipsychotic) has been documented at high psychiatric doses (30-60 g/day): glycine's therapeutic efficacy for schizophrenia negative symptoms is less consistent when patients are co-administered clozapine, likely because clozapine itself occupies the NMDA receptor glycine-binding site. This interaction has not been studied at 3 g supplemental doses; the clinical relevance at that dose is unknown but theoretically possible.
- Formal supplemental safety data in pregnant and nursing women are lacking; standard caution applies.
- At the 3 g/day dose used in sleep studies, tolerability has been described as good with no serious adverse effects reported across published trials.
- This paper is a rat mechanistic study; the doses used (1-2 g/kg body weight oral in rats) are not directly translatable to human supplemental doses. The mechanistic pathway identified (NMDA co-agonism at the SCN glycine site) is the same mechanism underlying the theoretical clozapine interaction noted at compound level.
When to take it
Best taken: evening
What we make of it
A rodent study explaining the mechanism, not a human trial.
The detail
The paper is a mechanistic study in rodents. It works out how glycine lowers core temperature through a brain pathway — useful for understanding why it might work, not evidence that it does in people.