Glycine
The simplest amino acid, yet one of the most important for brain function and sleep quality. Glycine is an inhibitory neurotransmitter (like GABA), a co-agonist at NMDA receptors (enhancing learning), and a critical building block for glutathione (the body's master antioxidant). Taking 3g before bed reliably improves sleep quality and next-day cognitive performance.
Dosage
For sleep: 3 g taken 30-60 minutes before bed. For general nootropic use: 1-3 g daily. For NMDA co-agonism (with racetams): 1-3 g daily. Sweet taste, dissolves easily.
Dosages shown are for research reference only. Always consult a qualified healthcare provider.
Half-Life
1-2 hours (plasma)
Administration
Oral (powder, capsules). Sweet-tasting powder dissolves easily in water.
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Mechanism of Action
Glycine acts as an inhibitory neurotransmitter by binding to strychnine-sensitive glycine receptors (GlyR) in the brainstem, spinal cord, and retina, hyperpolarizing neurons via chloride influx. It also serves as a mandatory co-agonist at the glycine-binding site (NR1 subunit) of NMDA glutamate receptors — without glycine binding, NMDA receptors cannot open their ion channel even when glutamate is present. This dual role means glycine both calms neural activity (sleep, anti-anxiety via GlyR) and supports excitatory learning processes (NMDA-dependent LTP and memory consolidation). Glycine lowers core body temperature at night by promoting peripheral vasodilation through nitric oxide, which improves sleep onset. It is a precursor for glutathione synthesis and modulates the glycinergic system in the suprachiasmatic nucleus.
Regulatory Status
Dietary supplement worldwide. GRAS ingredient. No prescription required.
Risks & Safety
Common
Essentially none at standard doses. Sweet taste makes it easy to take.
Serious
None documented. One of the safest supplements available.
Rare
Nausea, soft stools at very high doses (>10 g).
Compare Glycine With
Research Papers
10Published: January 26, 2012
AI Summary
We recently reported that glycine ingestion before bedtime significantly ameliorated subjective sleep quality in individuals with insomniac tendencies. Oral administration of glycine to rats was found to induce a significant increase in the plasma and cerebrospinal fluid glycine concentrations and a significant decrease in the core body temperat...
Published: March 17, 2004
AI Summary
Glycine is an essential component of important biological molecules, a key substance in many metabolic reactions, the major inhibitory neurotransmitter in the spinal cord and brain stem, and has anti-inflammatory, cytoprotective, and immunomodulatory qualities.
Published: February 28, 2017
AI Summary
Glycine is very effective in improving the health and supports the growth and well-being of humans and animals. In this review we will focus on the metabolism of glycine in humans and animals and the recent findings and advances about the beneficial effects and protection of glycine in different disease states.
Published: November 25, 1998
AI Summary
There is substantial experimental evidence that free glycine may have a role in protecting tissues against insults such as ischemia, hypoxia, and reperfusion. Although this may have unexpected benefits when such solutions are used in clinical practice, it does raise the specter of a possible confounding effect in experiments when glycine is adde...
Published: June 6, 2025
AI Summary
The glycine receptor is found within the central nervous system and peripheral nervous system. It has also been found within amacrine cells, as well as renal medulla and cortex.
Published: September 14, 2025
AI Summary
Glycine deficiency has been reported due to inadequate protein intake, malnutrition, late gestation, diabetes, insulin resistance, and increased exposure to xenobiotics. Replacing a part of the glycine with l-serine should avoid (i) glycine flux through SHMT towards l-serine associated with the loss of methylenetetrahydrofolate, a substance esse...
Published: July 4, 2017
AI Summary
The review summarizes the recent literature on the role of glycine in skeletal muscle during times of stress.
Published: May 10, 2022
AI Summary
It is mainly generated in the liver and kidney and is used to produce collagen, creatine, glucose and purine. Here, we reviewed the current evidence supporting the role of glycine in the development and treatment of metabolic syndrome components.
Published: November 10, 2021
AI Summary
The suitability of modulating glycinergic neurotransmission for the treatment of inflammatory and chronic pain has gained widespread recognition, with glycine receptors (GlyRs) and glycine transporters (GlyT1 and GlyT2) now considered key therapeutic targets [...].
Published: July 20, 2002
AI Summary
Several full or partial glycine-site agonists, including glycine, D-serine and D-cycloserine, have shown effectiveness in small-scale clinical trials. Glycine levels in brain are regulated by GLYT1-type glycine transporters.
Frequently Asked Questions
What is Glycine used for?
The simplest amino acid, yet one of the most important for brain function and sleep quality. Glycine is an inhibitory neurotransmitter (like GABA), a co-agonist at NMDA receptors (enhancing learning), and a critical building block for glutathione (the body's master antioxidant). Taking 3g before bed reliably improves sleep quality and next-day cognitive performance.
What are the side effects of Glycine?
Common: Essentially none at standard doses. Sweet taste makes it easy to take. Serious: None documented. One of the safest supplements available. Rare: Nausea, soft stools at very high doses (>10 g).
How is Glycine administered?
Glycine is administered via oral (powder, capsules). sweet-tasting powder dissolves easily in water..
What is the half-life of Glycine?
The half-life of Glycine is 1-2 hours (plasma).
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