What it’s for
- Studied for sleep and next-day fatigue
An amino acid found in protein foods and sold as a separate supplement.
Purpose, evidence and practical considerations.
Small, short studies suggest possible improvements in subjective fatigue after restricted sleep. They do not establish a durable insomnia treatment or benefits from much larger doses.
Confidence: weak
Short studies at a few grams report mostly mild gastrointestinal effects. Long-term bedtime use, pregnancy and use with significant kidney or liver disease are not well characterized.
Glycine is an amino acid and neurotransmitter. Small human experiments suggest bedtime glycine may influence thermoregulation and subjective sleep, but the mechanism and durable clinical effect remain uncertain.
Regulatory status: amino acid and dietary supplement ingredient; not an FDA-approved insomnia treatment
The evidence on this page does not automatically apply to:
How people use it, with their schedules, context and original sources.
2 g · 3–4 nights per week · with the sleep stack, 30–60 min before bed
2 g · nightly · night stack
night stack (sleep)
Amount and timing patterns reported in public protocols; these are observations, not instructions. Private and hidden usage is excluded.
Brand variants reported in public protocols. Private entries are excluded, and inclusion is not an endorsement.
Glycine is listed as an ingredient or component in these reviewed interventions.
These share a protocol with this intervention. This does not establish that they work together or are suitable alternatives.