Glycine (3 g pre-bed)
Inhibitory amino acid with small RCT signal for subjective sleep quality at 3 g pre-bed.
Why
Glycine is a small inhibitory amino acid. Both a neurotransmitter and a collagen substrate. Small Japanese RCTs (Yamadera 2007, Bannai 2012) report improvements in subjective sleep quality and reduced daytime sleepiness with 3 g pre-bed. Mechanism appears to involve mild peripheral vasodilation that drops core body temperature (sleep-onset signal). Also used as collagen-synthesis substrate alongside vitamin C and other amino acids.
How it works
Activates NMDA-receptor glycine-binding site centrally and inhibitory glycine receptors in spinal cord. Peripherally, mild vasodilation drops core body temperature, the documented mechanism for the sleep-onset effect. Glycine is one of the three glycogenic amino acids in collagen (along with proline and hydroxyproline).
Expected onset · Sleep effects often within days (acute pharmacodynamic effect)
How to take
Dosage
Sleep: 3 g 30–60 min before bed. Collagen synthesis support: 5–10 g/day divided.
Timing
Sleep dose at bedtime; collagen dose across the day
On the label
'Glycine' powder is most cost-effective for the 3 g dose. Stated grams per scoop.
Ideal for
Adults with mild sleep-onset difficulty exploring nutrient-based approaches; people supporting collagen synthesis.
Safety
Evidence
Yamadera 2007 Sleep Biol Rhythms RCT: glycine 3 g pre-bed improved subjective sleep quality and PSG sleep-onset markers vs placebo. Bannai 2012 Front Neurol crossover RCT documented reduced daytime sleepiness after partial sleep restriction. Preliminary, RCTs exist in non-tier-1 journals but are small or short-duration. No Cochrane review, EMA monograph or EFSA-authorised claim covers the indication.
Preliminary, RCTs exist in non-tier-1 journals but are small or short-duration. No Cochrane review, EMA monograph or EFSA-authorised claim covers the indication.
- Yamadera et al., Sleep Biol Rhythms 2007, glycine ingestion improves subjective sleep quality in human volunteers, correlating with polysomnographic changes
- Bannai et al., Front Neurol 2012, the effects of glycine on subjective daytime performance in partially sleep-restricted healthy volunteers (RCT)
- Inagawa et al., Adv Neuroimmune Biol 2006, assessment of effect of glycine intake on quality of sleep using PSG
Where to get it
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