Glycine

Also known as: glycine powder, aminoacetic acid

Grade B — Moderate Evidenceamino acidsleep
3–5 g30-60 min before bed. Reduces core body temperature for sleep onset.

Glycine is the simplest amino acid and serves as an inhibitory neurotransmitter in the brainstem and spinal cord. Research shows it improves sleep quality by lowering core body temperature — a key signal for sleep onset. Beyond sleep, glycine is a major component of collagen (making up about one-third of its amino acid content), supports glutathione production, and has been studied for its role in healthy aging and metabolic health.

TL;DR: Inhibitory amino acid that improves sleep quality by lowering core body temperature. Also supports collagen synthesis.

🌙Sleep🧬Longevity🦠Gut Health
Last reviewed: 2026-03-12

Quick Facts

Evidence

Grade B

Studies

3

Interactions

1

Forms

1

Evidence Rating: Grade B — Moderate Evidence

Some RCTs with positive results, or strong observational evidence. More research may refine our understanding.

Interaction Warnings

ClozapineModerate

Glycine modulates NMDA receptors; may affect clozapine efficacy

Important Notes

  • Very safe amino acid
  • Slightly sweet taste — mixes easily in water
  • Combines well with magnesium glycinate for sleep

Clinical Evidence (3 studies)

Glycine improved daytime performance in sleep-restricted volunteers

Bannai M et al. (2012) — Front Neurol

Glycine 3g improved daytime performance in sleep-restricted healthy volunteers

View on PubMed

Glycine improves subjective sleep quality

Bannai M & Kawai N (2012) — Sleep Biol Rhythms

Improved subjective sleep quality in insomnia-prone individuals

View on PubMed

Mechanism: glycine promotes sleep via NMDA receptors

Kawai N et al. (2015) — Neuropsychopharmacology

Glycine promotes sleep via NMDA receptors in suprachiasmatic nucleus

View on PubMed

Alternatives to Consider

These supplements target similar goals and may be worth considering alongside or instead of Glycine.

NAC (N-Acetyl Cysteine)

Grade B

Precursor to glutathione (master antioxidant). Strong evidence for respiratory health, liver support, and psychiatric conditions.

🧬 Longevity🦠 Gut Health

Magnesium Glycinate

Grade A

Highly bioavailable form of magnesium. Strong evidence for sleep quality, muscle relaxation, and stress reduction. Most adults are deficient.

🌙 Sleep

Melatonin

Grade A

Natural sleep hormone. Lower doses (0.3-1mg) are often more effective than high doses. Best for sleep onset and circadian reset.

🌙 Sleep

Related Supplements

NAC (N-Acetyl Cysteine)

Grade B — Moderate Evidence

Precursor to glutathione (master antioxidant). Strong evidence for respiratory health, liver support, and psychiatric conditions.

Berberine

Grade A — Strong Evidence

Potent plant alkaloid with metformin-like effects on blood sugar. Also activates AMPK (longevity pathway). Multiple drug interactions.

Curcumin

Grade B — Moderate Evidence

Potent anti-inflammatory from turmeric. Must enhance bioavailability with piperine or specialized formulations.

GABA

Grade B — Moderate Evidence

The main inhibitory neurotransmitter. PharmaGABA form shows RCT evidence for relaxation and sleep. May work via gut-brain axis.

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⚕️ Important Disclaimer

This information is for educational purposes only. It is not medical advice. Always consult a healthcare provider before starting any supplement regimen, especially if you take medications or have health conditions.

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