Glycine
Glycine
Key Benefits
Sleep Quality
Lowers core body temperature and promotes deeper, more restorative sleep without grogginess.
Collagen Support
Comprises 33% of collagen structure, supporting skin, joints, and connective tissue.
Neuroprotection
Acts as inhibitory neurotransmitter, supporting calm and cognitive function.
Activation Synergies
Recommended Dosage
medical_servicesTake 3-5g 30-60 minutes before bed for sleep benefits. Tasteless powder can be mixed with water. No tolerance or dependency.
Deficiency Indicators
- Poor sleep quality or difficulty staying asleep
- Restless mind at night
- Joint or skin issues
Scientific Citations
Glycine: Research Summary
Research & Sources
What the evidence says — with links to the original studies
Glycine's foundational biochemical roles are well established: it is a substrate for collagen and glutathione synthesis and acts as an inhibitory neurotransmitter and obligatory NMDA-receptor co-agonist. As a supplement, the most studied claim is that 3 g before bed improves sleep, supported by small human trials and a well-characterized mechanism in which glycine lowers core body temperature via NMDA-mediated cutaneous vasodilation in the suprachiasmatic nucleus. Evidence for glutathione restoration (via GlyNAC), collagen support, and glycemic/metabolic benefit is promising but rests on small or combination-product trials, so the therapeutic case remains emerging rather than definitive.
Supporting Evidence
Oral glycine induced NREM sleep, shortened latency and lowered core temperature via peripheral vasodilation; blocked by NMDA antagonists and abolished by SCN lesion. Core temperature/thermoregulation mechanism paper.
3 g glycine before bed shortened polysomnographic latency to sleep onset and slow-wave sleep and reduced daytime sleepiness without changing sleep architecture.
3 g glycine 30 min before bed reduced fatigue (day 1) and improved psychomotor vigilance in sleep-restricted adults. Small sample (n=7).
Glycine + N-acetylcysteine corrected glutathione deficiency, cut oxidative stress and improved physical function. Glycine combined with NAC, so isolated glycine effect not separable.
Circulating glycine consistently low in T2D and inversely associated with insulin resistance; glycine stimulates insulin secretion and suppresses hepatic glucose output. Causal direction unresolved.
Glycine/proline/hydroxyproline are ~57% of collagen amino acids; endogenous glycine synthesis is inadequate for maximal collagen production, supporting dietary supply.
Full-text & official documents
- download Bannai et al. 2012 - Glycine and daytime performance in sleep-restricted volunteers (open-access PDF, Frontiers in Neurology)
- download Kumar et al. 2021 - GlyNAC supplementation pilot clinical trial (open-access full text, Clinical and Translational Medicine)
- download Dakhovnik, Ewald et al. 2025 - Collagen amino acid composition (glycine:proline:hydroxyproline) reduces biological age (open access, npj Aging)
Educational summary of published research — not medical advice. Consult a qualified professional before supplementing.
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