OnePin Peptide Library · Sleep
Glycine
Glycine USP
Glycine is the simplest amino acid (a single carbon backbone with an amino group) and the second-most abundant amino acid in the human body. It is classified as conditionally essential - the body synthesizes ~3g/day endogenously from serine, but optimal intake (especially for collagen synthesis and glutathione production) likely exceeds endogenous synthesis. Glycine is the most abundant amino acid in collagen (33% of all collagen residues), and collagen turnover represents the largest amino acid demand in the body.,Glycine has multiple roles: it is an inhibitory neurotransmitter in the spinal cord and brainstem (acting at glycine receptors), a co-agonist at NMDA receptors in the brain, a precursor to glutathione (along with cysteine and glutamate), the conjugating partner for bile acid synthesis (glycocholate), the rate-limiting substrate for heme/porphyrin synthesis, and a major contributor to creatine biosynthesis.,In recent years glycine has gained attention for sleep quality (3g pre-bed shown to reduce subjective fatigue and improve next-day cognition), longevity (the GlyNAC combination from Baylor College of Medicine showed restoration of glutathione, mitochondrial function, and biomarkers of aging in older adults), and metabolic health. Glycine deficiency is increasingly recognized as a likely contributor to age-related glutathione depletion and oxidative stress.
Sleep dose: 3g 30-60 minutes before bed (powder dissolved in water has a sweet taste, mixes well). Glutathione/longevity dose: 5-10g daily, often combined with NAC (GlyNAC stack). Can take with food or fasted.
Start here. Every protocol below is ordered lowest-first. Begin at the smallest effective dose, hold about a week to assess tolerance, and step up only if needed.
How it works
Glycine acts as the major inhibitory neurotransmitter in the spinal cord and brainstem via strychnine-sensitive glycine receptors. In the forebrain, glycine acts as an obligatory co-agonist at the NMDA glutamate receptor (binding the glycine-B site), required for NMDA receptor activation. This dual role - inhibitory at one type of receptor, facilitating at another - allows glycine to modulate excitatory balance throughout the CNS.,Pre-sleep glycine is thought to improve sleep quality by reducing core body temperature (peripheral vasodilation) and modulating thermoregulation, which signals sleep onset. It also acts at glycine receptors and NMDA receptors in sleep-regulatory areas (including suprachiasmatic nucleus).,Glycine is one of three substrates for glutathione (GSH) synthesis (with cysteine and glutamate). Cysteine is typically rate-limiting, but in older adults glycine becomes co-rate-limiting due to declining endogenous synthesis. The Baylor GlyNAC studies showed combining glycine + NAC dramatically restored glutathione vs NAC alone in older adults.,Glycine is the dominant amino acid in collagen (33% of residues), making collagen turnover the largest demand on body glycine pools. Joint, tendon, skin, and bone health all depend on adequate glycine availability for collagen synthesis.,Bile acid conjugation: glycine + cholic acid forms glycocholate, the major conjugated bile acid. This affects fat and fat-soluble vitamin absorption.,Glycine is a precursor to creatine (along with arginine and methionine), porphyrin/heme synthesis, purines, and glyoxylate.
Glycine acts as the major inhibitory neurotransmitter in the spinal cord and brainstem via strychnine-sensitive glycine receptors. In the forebrain, glycine acts as an obligatory co-agonist at the NMDA glutamate receptor (binding the glycine-B site), required for NMDA receptor activation. This dual role - inhibitory at one type of receptor, facilitating at another - allows glycine to modulate excitatory balance throughout the CNS.,Pre-sleep glycine is thought to improve sleep quality by reducing core body temperature (peripheral vasodilation) and modulating thermoregulation, which signals sleep onset. It also acts at glycine receptors and NMDA receptors in sleep-regulatory areas (including suprachiasmatic nucleus).,Glycine is one of three substrates for glutathione (GSH) synthesis (with cysteine and glutamate). Cysteine is typically rate-limiting, but in older adults glycine becomes co-rate-limiting due to declining endogenous synthesis. The Baylor GlyNAC studies showed combining glycine + NAC dramatically restored glutathione vs NAC alone in older adults.,Glycine is the dominant amino acid in collagen (33% of residues), making collagen turnover the largest demand on body glycine pools. Joint, tendon, skin, and bone health all depend on adequate glycine availability for collagen synthesis.,Bile acid conjugation: glycine + cholic acid forms glycocholate, the major conjugated bile acid. This affects fat and fat-soluble vitamin absorption.,Glycine is a precursor to creatine (along with arginine and methionine), porphyrin/heme synthesis, purines, and glyoxylate.
What to expect
Nights 1-7: Sleep quality improvements, faster onset.
Evidence
Interactions & stacking
What's safe to combine, and what belongs in a separate pin.
Safe & synergistic
Keep separate
Pharmacokinetics
Storage. Store at room temperature (20-25C) in a cool, dry place. Powder is hygroscopic - keep tightly sealed. Capsules shelf-stable 2+ years.
Regulatory status
Classified as a dietary supplement in the US - no prescription required. Widely available. Used as a food ingredient (sweetener) and in IV fluids in hospital settings. No medical indications approved by FDA but extensive safety record.
Put it to work
Calculate, log & track
Open Glycine straight into OnePin with your vial and dose pre-filled, then let it handle the syringe math and remind you before the vial runs out.
Open Glycine in the app →Go deeper
The guide & community
The complete Glycine walkthrough, real protocol discussion and coaching live inside the BlessUp community on Skool.
Join the community ↗