Glycine
Simple amino acid that improves sleep quality, supports collagen synthesis, and may promote longevity
Bottom Line
Glycine is one of the simplest, cheapest, and most underrated sleep supplements. Taking 3g before bed consistently improves subjective sleep quality, reduces time to fall asleep, and helps you wake feeling more refreshed, with virtually no side effects.
The mechanism is elegant: glycine lowers core body temperature, which is a key signal for sleep initiation. It also acts on NMDA receptors in the brain's sleep centers and may increase serotonin availability.
Beyond sleep, glycine is a building block for collagen (every third amino acid), a precursor to glutathione (master antioxidant), and has been shown to extend lifespan in animal models by mimicking methionine restriction.
At $0.10-0.30/day with essentially no downside, glycine is worth trying for anyone with sleep issues or interested in longevity. It's the rare supplement where the risk/reward ratio is strongly favorable.
Science
How Glycine Improves Sleep:
- Thermoregulation - Glycine causes peripheral vasodilation, which dissipates heat from the body's core. This drop in core temperature is a critical signal for sleep onset. Studies show glycine reduces core body temperature by ~0.5°C.
- NMDA Receptor Modulation - Glycine acts on NMDA receptors in the suprachiasmatic nucleus (the brain's master clock), promoting sleep through neural mechanisms.
- Serotonin Pathway - Glycine may increase serotonin availability in the brain, supporting both sleep and mood.
Clinical Evidence:
- Yamadera et al. (2007): 3g glycine improved subjective sleep quality and reduced daytime sleepiness in people with sleep complaints
- Bannai et al. (2012): 3g glycine improved next-day cognitive performance in sleep-restricted subjects
- Kawai et al. (2015): Confirmed NMDA receptor mechanism in suprachiasmatic nucleus
Longevity Mechanisms:
- Methionine restriction mimetic - Glycine may counteract excess methionine (common in high-protein diets), activating longevity pathways
- Glutathione precursor - Combined with NAC (as "GlyNAC"), supports master antioxidant synthesis
- Collagen synthesis - Glycine is 33% of collagen; supplementation supports structural protein maintenance
- Autophagy activation - May promote cellular cleanup mechanisms
Animal Evidence:
- Glycine extended lifespan by 4-6% in genetically diverse mice
- GlyNAC extended lifespan by 24% in mice
Supporting Studies
7 peer-reviewed studies
View all studies & compare research →Practical Protocol
Basic Sleep Protocol:
| Parameter | Recommendation |
|---|---|
| Dose | 3 grams (3,000 mg) |
| Timing | 30-60 minutes before bed |
| Form | Powder (most economical) or capsules |
| Duration | Ongoing; benefits continue with use |
How to Take:
- Mix powder in water, tea, or take capsules
- Glycine has a mildly sweet taste (it's named after Greek "glykys" = sweet)
- Can be taken with or without food
- No need to cycle
Longevity/GlyNAC Protocol:
| Supplement | Dose | Timing |
|---|---|---|
| Glycine | 3g | Morning + evening |
| N-Acetylcysteine (NAC) | 600mg | Morning + evening |
This combination (studied by Baylor researchers) supports glutathione synthesis and showed remarkable improvements in older adults.
Collagen Support Protocol:
- 3-10g glycine daily
- Combine with vitamin C (supports collagen synthesis)
- Can add proline/hydroxyproline (collagen peptides)
Product Recommendations:
- Bulk glycine powder - Most economical ($10-15 for months supply)
- Glycine capsules - More convenient, slightly pricier
Risks & Side Effects
Safety Profile: Excellent
Glycine is one of the safest supplements available:
- Non-essential amino acid (body produces it)
- No known toxicity at typical doses
- No habituation or dependence
- No morning grogginess
Potential Side Effects (Rare):
- Mild GI discomfort at very high doses (>10g)
- Soft stools in some individuals
- Theoretically could lower blood pressure slightly
Contraindications:
- Clozapine users (glycine may interact)
- Those on blood pressure medications (monitor)
- Consult doctor if pregnant/nursing
Drug Interactions:
- May enhance effects of sleep medications
- Possible interaction with clozapine (schizophrenia medication)
- Generally very safe to combine with other supplements
Who It's For
Ideal For:
- Anyone with difficulty falling asleep
- Those who wake feeling unrefreshed
- People on high-protein/meat-heavy diets (may need more glycine)
- Longevity-focused individuals
- Those wanting to support skin/joint health
- Budget-conscious supplement users
Especially Beneficial:
- Older adults (glycine levels decline with age)
- Those with sleep complaints but want to avoid sleep medications
- People who run "hot" at night
May Not Need:
- Those with excellent sleep already
- People eating lots of collagen-rich foods (bone broth, skin, etc.)
How to Track Results
Sleep Metrics:
- Subjective sleep quality (1-10 scale)
- Time to fall asleep
- Morning refreshedness
- HRV trends (expect improvement)
Tools:
- Sleep diary or app
- Oura Ring for sleep staging
- Simple morning energy rating (1-10)
Timeline:
- Sleep effects: Often same night or within 1 week
- Consistent benefits: 2-4 weeks
- Collagen/skin benefits: 8-12 weeks
Signs It's Working:
- Falling asleep faster
- Waking more refreshed
- Less grogginess
- Improved HRV
- Better skin hydration (long-term)
Top Products
Recommended:
- NOW Foods Glycine Powder - Pure, affordable bulk powder
- Thorne Glycine - Capsule form, trusted brand
- Nutricost Glycine - Budget-friendly bulk option
What to Look For:
- Pure glycine (no fillers)
- Powder is most economical
- Capsules for convenience
- Third-party tested preferred
Cost Breakdown
Monthly Cost: $10-20
Per dose: $0.10-0.30 for 3g
Bulk powder: Most economical ($0.10/dose) Capsules: More convenient ($0.20-0.30/dose)
Cost-effectiveness:
One of the cheapest effective sleep supplements. Better cost-per-benefit than most sleep aids.
Podcasts
The 12 Greatest Mood Boosters on Earth : 1397
Dave Asprey sits down with biohacker and performance researcher Lucas Aoun in Dubai for a deep...
Peptide & Hormone Therapies for Health, Performance & Longevity | Dr. Craig Koniver
Andrew Huberman hosts Dr. Craig Koniver, a board-certified physician specializing in performance...
Startled?! Try Glycine!
Chris Masterjohn explores the calming effects of glycine supplementation, particularly its role...
Discussed in Podcasts
Methylated B vitamins and TMG lower homocysteine, a cardiovascular risk marker
Elevated homocysteine raises cardiovascular risk. Methylated B12, folate, and TMG lower it through liver detox pathways.
Glycine at 3,000-5,000 mg calms the nervous system and supports liver detox before bed
Glycine is an inhibitory neurotransmitter that calms the nervous system at high doses. It also supports phase two liver detoxification.
Glycine calms the startle reflex via spinal cord
GABA inhibits the startle reflex in the brainstem while glycine inhibits the motor response in the spinal cord, reducing exaggerated reactions.
Glycine counters BCAA-driven insulin resistance in metabolically broken people
Brad Marshall explains his emergence diet based on collagen and gelatin (broth). In some people, metabolism shifts to a torpor-like state where branched-chain amino acids cannot be properly broken down, contributing to insulin resistance. Glycine appears to counter-regulate this effect. BCAAs themselves are fine and even thermogenic in people who can metabolize them efficiently, but for those in a metabolically dysfunctional state, glycine from collagen-rich foods helps restore balance.
I think you promote Lifeblood as well
you know what if i balance it out with some gelatin and it's like yeah you could do that but you still want the benefits of the glycine there you don't just want it to all be counteracting the other...
Who to Follow
Researchers:
- Makoto Bannai, PhD - Japanese researcher who conducted seminal glycine-sleep studies
- Rajagopal Sekhar, MD - Baylor researcher studying GlyNAC for aging
Advocates:
- Rhonda Patrick, PhD - Covers glycine in longevity context
- David Sinclair, PhD - Mentions glycine as part of longevity protocols
Synergies & Conflicts
Pairs Well With:
- Magnesium - Complementary sleep mechanisms
- NSDR - Non-sleep deep rest + glycine for recovery
- Morning Sunlight - Circadian support
- NAC - GlyNAC combination for longevity
Timing Considerations:
- Take 30-60 min before bed for sleep
- Morning dose if using for longevity/GlyNAC
- Can split doses if taking >3g
Stack Suggestions:
What People Say
Research Base:
Community Feedback:
Criticisms: