Glycine
Simplest amino acid. Inhibitory neurotransmitter in the spinal cord and brainstem (glycine receptor agonist). Precursor to glutathione (GSH) and collagen. Reduces core body temperature via peripheral vasodilation, facilitating sleep onset.
Bannai et al. (2012) showed 3 g glycine before sleep improved subjective sleep quality, reduced daytime sleepiness, and improved cognitive performance next day vs placebo. Mechanism likely: peripheral vasodilation → heat dissipation → faster sleep onset + deeper non-REM. Also a mTOR modulatory amino acid — relevant to longevity stacks. NAC + Glycine (NAC+G) combination improves glutathione in aging populations (Kumar 2021 trial).
Very safe. Clozapine interaction (glycine antagonizes clozapine's antipsychotic effect via glycine transporter competition) — clinically relevant only in schizophrenia management. Hypotonic shock reported at IV glycine use in prostate surgery (not relevant to oral supplementation).
External links to PubMed searches, ClinicalTrials.gov, and FDA materials. We do not host papers — we point at canonical sources.
GRAS (Generally Recognized as Safe). Dietary supplement (DSHEA). No FDA drug approval.
Distilled themes from named communities — Reddit threads, forums, creator commentary. Not direct quotes; not clinical evidence. Useful for calibrating expectations against what real self-experimenters report.
Underrated in r/Nootropics relative to popularity. Most common use: 3 g with melatonin as a sleep stack. NAC+Glycine combination for glutathione is growing — driven by the Kumar 2021 aging paper.