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Glycine

Evidence: ★★★☆☆ · Status: OTC Supplement

💡 Did you know? Glycine — the simplest amino acid — lowers your core body temperature at night, and that drop is one reason it helps you fall asleep faster.

In plain English

An amino acid that gently cools you down and quiets the nervous system for sleep, and is the main brick in collagen. Dirt cheap, very safe.

How it works

Smallest amino acid; inhibitory neurotransmitter at spinal/brainstem glycine receptors (GLRA1), lowers core body temperature (a sleep-onset trigger) via peripheral vasodilation, and supplies one-third of collagen's amino acids. Mimics some benefits of methionine restriction (a longevity lever).

Molecular target & official sources

GLRA1 glycine receptor (NCBI Gene) · Glycine (PubChem CID 750)

Protocol

3–5 g before bed; 5–10 g with collagen + vitamin C for tendons.

Bottom line

One of the most undervalued supplements — sleep + connective tissue + longevity.

Helps with: Sleep Better · Live Longer · Joint Health · Skin & Hair

Stacks with

Magnesium before bed — the two together noticeably deepen sleep.

Shares a pathway — often paired with: Caffeine, PDE-5 Inhibitors (Sildenafil / Tadalafil), Minoxidil, L-Citrulline / Citrulline Malate.

Availability & where to buy

Available over the counter. Widely available OTC — e.g. iHerb (ships worldwide); in Singapore also Guardian, Watsons, GNC, Shopee / Lazada. Look for a third-party-tested / GMP mark and check the dose per serving. Very cheap — ~S$10–20/month; it’s sweet, mixes into water.

How it works: the Nitric oxide / cGMP pathway →

Used in these protocols

Compare Glycine

Common questions

Does Glycine actually work?

Human-evidence rating: 3 of 5. One of the most undervalued supplements — sleep + connective tissue + longevity.

How do you take Glycine?

3–5 g before bed; 5–10 g with collagen + vitamin C for tendons.

Is Glycine legal or approved?

Regulatory status: OTC Supplement.