Glycine
The simplest amino acid with profound effects on sleep, collagen, and longevity
Also known as: Aminoacetic Acid • Gly
Overview
Glycine is the smallest and simplest amino acid, yet it plays remarkably diverse roles in human physiology. It serves as a building block for proteins (especially collagen, where it comprises every third amino acid), a precursor for glutathione (the body's master antioxidant), an inhibitory neurotransmitter in the central nervous system, and a key component of creatine synthesis. Recent research has elevated glycine's status dramatically — the GlyNAC (Glycine + N-Acetyl Cysteine) combination has shown remarkable anti-aging effects in clinical trials at Baylor College of Medicine, reversing multiple hallmarks of aging in older adults. Glycine's sleep-promoting effects are also well-established: 3g before bed lowers core body temperature and improves sleep quality without morning grogginess.
Key Benefits
Sleep Quality Enhancement
3g of glycine before bed significantly improves sleep quality by lowering core body temperature through peripheral vasodilation. Studies show reduced sleep latency, improved sleep efficiency, and less daytime fatigue — without the grogginess of sedative sleep aids.
Glutathione Production (GlyNAC)
Glycine is a rate-limiting precursor for glutathione, the body's master antioxidant. The GlyNAC combination (glycine + NAC) restored glutathione levels in older adults and reversed oxidative stress, mitochondrial dysfunction, inflammation, and insulin resistance in Baylor clinical trials.
Collagen Synthesis
Glycine makes up approximately 33% of collagen — every third amino acid in the collagen triple helix is glycine. Supplementation supports skin, joint, bone, and connective tissue health by providing the primary building block for collagen production.
Neuroprotection
As an inhibitory neurotransmitter, glycine has calming effects on the central nervous system. It also acts as a co-agonist at NMDA receptors, playing a role in memory, learning, and neuroprotection.
Dosage & How to Take
3-5g daily for sleep; 7-10g daily for GlyNAC anti-aging protocol
| Purpose | Dose | Notes |
|---|---|---|
| Sleep improvement | 3g before bed | Dissolve in water — slightly sweet taste |
| GlyNAC anti-aging | 7g glycine + 7g NAC daily | Based on Baylor clinical trials |
| Collagen support | 3-5g daily | Can combine with collagen peptides |
| General wellness | 3g daily | With any meal or before bed |
Best Time to Take
Before bed for sleep; divided doses with meals for other benefits
With or Without Food
Can be taken with or without food. Dissolves easily in water with a pleasant sweet taste.
Forms & Bioavailability
| Form | Absorption | Best For | Notes |
|---|---|---|---|
| Pure Powder | Excellent | All purposes | Slightly sweet taste, dissolves easily — the preferred form |
| Capsules | Excellent | Convenience | Need many capsules for therapeutic doses (3-7g) |
| As part of collagen peptides | Good | Collagen support | Collagen is ~33% glycine |
Side Effects & Safety
Common
- Extremely well-tolerated at recommended doses
- Mild GI upset at very high doses (10g+)
Rare
- Nausea at very high doses
Contraindications
- Clozapine users (glycine may reduce clozapine effectiveness)
Interactions
May reduce clozapine effectiveness
Additive sleep-promoting effects
Scientific Research
Glycine and Sleep Quality
3g glycine before bed improved subjective sleep quality, reduced daytime sleepiness, and improved cognitive performance the next day
GlyNAC and Aging (Baylor)
GlyNAC supplementation in older adults corrected glutathione deficiency and improved oxidative stress, mitochondrial dysfunction, inflammation, insulin resistance, and physical function
Sleep Mechanism
Glycine promotes sleep by lowering core body temperature through activation of NMDA receptors in the suprachiasmatic nucleus
Food Sources
Frequently Asked Questions
Medical Disclaimer
This content is for educational and informational purposes only and is not intended as medical advice. Always consult with a qualified healthcare professional before starting any supplement regimen, especially if you have pre-existing health conditions or are taking medications. The statements on this page have not been evaluated by the Food and Drug Administration.