Glycine

2,000mg

Inhibitory neurotransmitter that lowers core body temperature at night, improving sleep onset and quality. Also the rate-limiting amino acid for both collagen and glutathione synthesis.

Category Performance
Dose 2,000mg
Form Free amino acid - pharmaceutical grade
Evidence Level Strong - multiple RCTs

Mechanism

Glycine is the simplest amino acid and acts as an inhibitory neurotransmitter in the central nervous system. It activates glycine receptors that suppress neuronal excitability - lowering core body temperature by 0.5-1°C, a key trigger for sleep onset.

Beyond sleep, glycine is the rate-limiting substrate for glutathione synthesis (the body's primary antioxidant) and for collagen production. Tissue glycine concentrations decline with age, making supplementation increasingly relevant.

Key Benefits

  • Conditionally essential amino acid, demand increases with age
  • Simplest of the 20 proteinogenic amino acids, pharmacopoeial grade ≥99%
  • Rate-limiting substrate for glutathione synthesis
  • Essential for collagen and connective tissue production
  • Conditionally essential amino acid. Demand increases with age

The Research

Peer-reviewed human trials supporting this ingredient at this dose.

Bannai M, Kawai N. (2012). J Pharmacol Sci. 118(2):145-8.New therapeutic strategy for amino acid medicine: glycine improves the quality of sleep.PubMed →
Kumar P, et al. (2021). Clin Transl Med. 11(3):e372.GlyNAC supplementation in older adults improves glutathione deficiency, oxidative stress, and mitochondrial dysfunction.PubMed →
Ramos-Jiménez A, et al. (2024). Sports (Basel). 12(10):265.An update of the promise of glycine supplementation for enhancing physical performance and recovery.PubMed →
In the formula

Glycine

2,000mg

Free amino acid - pharmaceutical grade

When to take it

Best taken at night, 30-60 minutes before sleep. Glycine lowers core body temperature - the physiological signal that initiates sleep onset.