Compound or practice · Supplement
Glycine
A cheap amino acid that lowers core temperature for easier sleep onset and supports collagen and glutathione.
- Overall grade
- Grade B
- Last revised
- 2
- graded outcomes
- 0
- references listed
A structured monograph in Prometheus's bundled library. Its grades are the monograph's own reading of the evidence, not a peer-reviewed review.
1 at grade B · 1 at grade C — 2 graded rows
What is known
Each outcome with its grade (how strong the evidence is, A to D), the size of the effect where the entry records one, and how often studies agree.
- Sleep onset / qualityEvidence grade B
3 g pre-bed
Smallmixed
- Next-day alertnessEvidence grade C
After better sleep
Smallmixed
What is uncertain
Read off the same rows as above. Nothing here is added that the entry does not itself record.
- Thin evidence: Next-day alertness (grade C).
- Studies disagree: Sleep onset / quality (mixed agreement).
- Watch with Melatonin: Both pre-bed and compatible — glycine 60–90 min out, melatonin ~30.
Interactions
Documented pairings with supplements and medicines. A medicine on this list is a conversation for whoever prescribes it.
The evidence in words
What it is
Glycine is the simplest amino acid, an inhibitory neurotransmitter, and a building block of collagen and glutathione. It is sweet-tasting and inexpensive.
How it works
Taken before bed, glycine promotes peripheral vasodilation that drops core body temperature — a physiological trigger for sleep onset — and acts on NMDA and glycine receptors involved in sleep regulation.
What the evidence shows
Small trials show 3 g before bed improves subjective sleep quality and next-day alertness, partly by speeding sleep onset. As a collagen precursor with the amino acid the modern diet is arguably short on, it also supports connective tissue and is a substrate for glutathione synthesis (relevant to NAC stacks).
How to use it
3 g dissolved in water 30–60 minutes before bed for sleep; higher doses (10 g+) are used in glutathione/metabolic research contexts.
Safety & interactions
Very safe and well tolerated at these doses. Magnesium — The evening onset-plus-architecture pairing. Melatonin — Both pre-bed and compatible — glycine 60–90 min out, melatonin ~30.
Bottom line
An underrated, cheap sleep-onset aid: 3 g before bed. Doubles as a collagen and glutathione building block.
How it is used
As the entry records it, from the studies it summarises. Not a recommendation for you — doses that suit a trial population may not suit you.
- Sleep
- 3 g in water, 30–60 min pre-bed.
Goes with
- MagnesiumThe evening onset-plus-architecture pairing.Evidence grade B
Related reading
Entries that share this one's tags or conditions.
- Glycine for Next-day alertnessEvidence grade C — After better sleepEvidence grade C
- Glycine for Sleep onset / qualityEvidence grade B — 3 g pre-bedEvidence grade B
- Glycine: dosage and how to take it3 g in water, 30–60 min pre-bed.Evidence grade B
- Glycine: side effects, safety & interactionsVery safe and well tolerated at these doses.Evidence grade B
Sources
This entry lists no references of its own.
Last revised . A grade is this entry's reading of the evidence, not medical advice.