Glycine is a conditionally essential amino acid that serves as an inhibitory neurotransmitter, a key component of collagen synthesis, a precursor to glutathione (with NAC), and a metabolic substrate for creatine synthesis. Our research shows solid evidence for sleep quality improvement — 3g before bed reduces sleep latency and improves subjective sleep quality without next-day drowsiness. It's remarkably safe, dirt cheap, and synergistic with NAC for glutathione production (GlyNAC protocol).
Glycine may reduce clozapine effectiveness (opposing NMDA mechanisms)
Glycine has mild vasodilatory properties
Not Prohibited
Bannai M et al. The effects of glycine on subjective daytime performance after sleep restriction.
Kumar P et al. Glycine and N-acetylcysteine (GlyNAC) supplementation in older adults improves glutathione deficiency.
Kawai N et al. Sleep-promoting and hypothermic effects of glycine.
Reviewed by the Scan Dose Research Team and Clinical Advisory Board | Last updated: April 2026
Not medical advice. Based on published clinical research and systematic reviews.