If you've struggled with sleep, you've probably tried melatonin, magnesium, maybe valerian root. But glycine—the simplest amino acid—might be the most underrated sleep compound available.
The research is compelling: glycine improves both how fast you fall asleep and how deeply you stay asleep, without the grogginess that comes with most sleep aids.
How Glycine Works for Sleep
Glycine doesn't just "calm you down." It works through a specific mechanism that scientists have mapped in detail.
When you take glycine, it crosses the blood-brain barrier and activates NMDA receptors in your suprachiasmatic nucleus (SCN)—the brain's master circadian clock. This triggers a cascade: blood vessels in your hands and feet dilate, heat dissipates from your extremities, and your core body temperature drops.
That temperature drop is critical. Your body must cool down 1-2°F to initiate and maintain sleep. When this cooling fails—from stress, age, or circadian disruption—you lie awake or cycle through lighter sleep stages.
Kawai N, et al. Neuropsychopharmacology. 2015;40(6):1405-1416.
What the Research Shows
Human trials on glycine are surprisingly consistent:
- Faster sleep onset. Polysomnography studies show glycine reduces the time to fall asleep and shortens latency to slow-wave (deep) sleep.
- Better subjective quality. Participants report feeling more rested, with less daytime fatigue—even after sleep restriction.
- No hangover effect. Unlike many sleep aids, glycine doesn't impair next-day alertness. If anything, studies show improved cognitive performance the following day.
Yamadera W, et al. Sleep and Biological Rhythms. 2007;5(2):126-131.
Bannai M, et al. Frontiers in Neurology. 2012;3:61.
Natural Sources of Glycine
While glycine supplements are widely available, this amino acid also occurs naturally in several foods and traditional medicinals.
Bone broth and collagen are the most concentrated dietary sources—collagen is roughly one-third glycine by weight. This partly explains why grandmothers have been recommending broth for sleep for generations.
Reishi mushroom (Ganoderma lucidum) is particularly interesting here. Research has identified glycine as one of reishi's most abundant amino acids, alongside glutamic acid and alanine (Sanodiya et al., 2009; Deepalakshmi et al., 2011). This may help explain the mushroom's traditional use for relaxation and sleep across centuries of Asian medicine.
Reishi contains over 400 bioactive compounds—polysaccharides, triterpenoids, nucleosides, amino acids—working in concert rather than isolation. It's a cornucopia of medicinal compounds that Western research is only beginning to unpack.
The catch with most commercial reishi: alcohol-based extraction can denature heat-sensitive amino acids like glycine. Water extraction preserves these compounds more effectively—one reason extraction method matters more than most consumers realize.
Glycine vs. Other Sleep Compounds
| Compound | Primary Mechanism | Best For |
|---|---|---|
| Glycine | Thermoregulation via NMDA receptors | Deep sleep, sleep maintenance |
| GABA | Neural inhibition | Sleep onset, anxiety |
| Melatonin | Circadian signaling | Jet lag, shift work |
| Magnesium | Muscle relaxation, GABA modulation | Physical tension, restless legs |
Glycine works through a different pathway than most sleep compounds. This means it can complement—rather than duplicate—other approaches.
Who Benefits Most from Glycine
Glycine tends to work best for people who:
- Fall asleep but don't stay asleep (wake during the night)
- Sleep enough hours but don't feel rested
- Run "hot" at night or have temperature regulation issues
- Want deeper sleep without sedative effects
If your primary issue is racing thoughts or anxiety at bedtime, GABA pathway support may be more directly helpful. Many people benefit from addressing multiple sleep pathways simultaneously.
Practical Recommendations
If you want to support sleep through glycine pathways:
- Consider natural sources like bone broth, collagen, or reishi mushroom
- Give any new approach at least a week—effects may build over time
- Combine with good sleep hygiene: cool room, consistent schedule, limited screens
- Track your sleep quality to assess impact
Glycine works best as part of a comprehensive approach, not a magic bullet. But for many people, it's the missing piece that makes everything else work better.
Multi-Pathway Sleep Support
Water-extracted reishi with naturally occurring glycine, GABA, choline, and adenine.
Try Reishi ElixirGlycine for Sleep: Frequently Asked Questions
How does glycine improve sleep?
Glycine promotes sleep through two primary mechanisms: it activates NMDA receptors in the suprachiasmatic nucleus (your brain's master clock), which triggers peripheral vasodilation and lowers core body temperature—a critical signal for sleep onset.
Are there natural sources of glycine for sleep?
Yes. While glycine supplements are available, it's also found in bone broth, collagen, and certain medicinal mushrooms. Reishi mushroom (Ganoderma lucidum) contains glycine as one of its most abundant amino acids, which may partly explain its traditional use for relaxation and sleep.
Can I take glycine with other sleep supplements?
Glycine works through different pathways than most sleep supplements (melatonin, GABA, magnesium), so it can generally be combined safely. However, consult your healthcare provider before combining any supplements, especially if you take medications.
This article is for educational purposes only and is not intended to diagnose, treat, cure, or prevent any disease. Consult your healthcare provider before beginning any new supplement regimen.
