Glycine
The simplest amino acid does an outsized amount of work. Improves sleep by dropping core temperature, supports collagen, calms the nervous system, and may extend lifespan.
Multiple RCTs on 3g pre-bed for subjective sleep quality and reduced daytime sleepiness. GlyNAC trials at Baylor show reversal of multiple aging markers (mitochondrial function, insulin resistance, inflammation, glutathione status). Sleep effects: within nights. Longevity markers: 16–24 weeks.
Glycine is technically non-essential (the body makes some), but functionally most people consume far less than is optimal. It's the smallest amino acid, but ~30% of all collagen and large amounts of glutathione and creatine are built from it. It also acts as an inhibitory neurotransmitter, binds GABA-A receptors, and lowers core body temperature when taken pre-bed — which is a powerful sleep signal. Recent longevity research (the GlyNAC trials at Baylor) shows glycine + NAC supplementation reverses several markers of biological aging in older adults.
- Form
- Plain glycine powder — slightly sweet, dissolves in water. Magnesium glycinate double-duty supplement. GlyNAC (glycine + NAC) — the longevity stack.
- Dose
- 3 g pre-bed for sleep. 5–10 g/day for collagen support. 100 mg/kg body weight/day in the GlyNAC longevity protocol (split AM/PM).
- Timing
- Pre-bed for sleep (30–60 min before). With food for collagen / general support.
- Schedule
- Daily.
- Side effects
- Generally well-tolerated. Mild GI upset at very high doses. Sedation if combined with sleep medications.
- Interactions
- Sedatives — additive. Clozapine — glycine modestly opposes its action.
- Contraindications
- None significant. Caution at high doses in severe kidney or liver disease.
- Lab markers
- Not routinely tested. Plasma amino acid panel if investigating broader status.
- Food sources
- Collagen-rich foods: bone broth, skin-on chicken, slow-cooked meats with connective tissue, gelatin, pork rinds. Almost no glycine in muscle-meat-only diets — collagen consumption matters.
Pairs with
NAC (the GlyNAC longevity stack — together they restore glutathione). Magnesium glycinate. Collagen peptides (glycine is the rate-limiting amino acid for collagen synthesis). L-Theanine and apigenin for sleep.
within Amino acids & derivatives