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Glycine

From the YapSpan Longevity Wiki · Updated 2026-09-28

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Glycine is an amino acid (a building block of protein) and an inhibitory neurotransmitter (a chemical messenger that calms nerve activity); as a supplement it is studied for sleep quality when taken as a single dose before bed.

Educational only, not a recommendation to take anything. YapSpan estimates are for reflection and entertainment only. They are not medical advice, a diagnosis, or a prediction of any individual outcome. Check with a doctor before making any medical decision.

Glycine is a non-essential amino acid with two roles in neurotransmission: it is an inhibitory transmitter at strychnine-sensitive glycine receptors, and a co-agonist at excitatory NMDA-type glutamate receptors [1]. In rats, oral glycine raised glycine concentrations in plasma and cerebrospinal fluid and lowered core body temperature while increasing blood flow to the skin [1]. A fall in core temperature normally accompanies the start of sleep (see sleep regulation), and this heat loss is the proposed route of glycine's effect [1]. A 2015 rat study located the site of action: oral glycine increased non-REM sleep and shortened the time to non-REM sleep with a simultaneous drop in core temperature; the rise in skin blood flow was blocked by the NMDA receptor antagonists AP5 and CGP78608 but not by the glycine receptor antagonist strychnine; glycine injected directly into the suprachiasmatic nucleus (SCN) raised skin blood flow; and destroying the SCN abolished both the sleep-promoting and the temperature-lowering effects [2]. The authors concluded that glycine promotes sleep through peripheral vasodilation driven by NMDA receptors in the SCN shell [2].

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In a study of volunteers who had persistently unsatisfactory sleep, 3 g of glycine taken before bedtime improved subjective sleep quality and sleep efficiency (time asleep as a share of time in bed) and shortened the polysomnographic latency both to sleep onset and to slow-wave sleep, without changing overall sleep architecture; participants also reported less daytime sleepiness and performed better on memory recognition tasks [3]. A review by the same research group reported that glycine before bedtime significantly improved subjective sleep quality in people with insomniac tendencies [1]. The authors described the profile as different from that of hypnotic drugs such as benzodiazepines, because sleep architecture was unchanged [3].

Categories: Supplements|Sleep|Dietary supplements|Longevity Wiki

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YapSpan estimates are for reflection and entertainment only. They are not medical advice, a diagnosis, or a prediction of any individual outcome. Check with a doctor before making any medical decision.

Biological mechanism

Evidence for sleep and insomnia

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