Home / Ingredient Directory / Glycine
Yannis Lopez
Reviewed by Yannis Lopez · Nutrition Industry Veteran
Last updated: July 3, 2026
Sleep & Recovery Amino Acid

Glycine

Sleep quality & calming support

Most abundant amino acid in collagen
Inhibitory neurotransmitter
Featured in: The Recovery Stack

FDA Disclaimer: These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease. Always consult your physician before starting any supplement.

Overview

Glycine is the simplest amino acid and one of the most abundant in the human body. It plays a critical role in collagen synthesis (making up about 33% of collagen), neurotransmitter function, and detoxification pathways. Unlike most amino acids, glycine has a calming, inhibitory effect on the nervous system.

In recent years, glycine has gained popularity as a sleep supplement. Research shows it can improve sleep quality, reduce the time to fall asleep, and enhance next-day alertness. It is often stacked with Magnesium and L-Theanine for comprehensive sleep support.

Potential Benefits

Sleep Quality

Multiple studies show glycine can improve sleep quality, reduce sleep latency, and enhance next-day cognitive function. It promotes a calm, relaxed state without sedation.

Collagen & Connective Tissue

Glycine is a major component of collagen. Supplementation may support skin, joint, and connective tissue health when combined with other amino acids.

Cognitive Function

May support memory and cognitive performance, especially under stress. Some research suggests benefits for schizophrenia and other neurological conditions.

Generally Well Tolerated

Glycine is very safe with an excellent safety profile. Most people tolerate it well even at higher doses (up to 10g+).

Typical Dosage
Daily Dose
3–5g
Often taken 30–60 minutes before bed
Best Taken
Evening / before bed
Can be mixed in water (slightly sweet taste)
Pro Tips
  • Take 30–60 minutes before bed for best sleep results
  • Stack with Magnesium and L-Theanine
  • Can be taken in the morning for cognitive support
  • Very safe even at higher doses (up to 10g+)
Research Snapshot

Multiple studies support glycine's benefits for sleep quality and next-day function. A 2012 study found that 3g of glycine before bed significantly reduced fatigue and daytime sleepiness following sleep restriction.

How Glycine Compares

Ingredient Best For Key Difference
Glycine Sleep Quality, Calming, Collagen Amino acid; inhibitory neurotransmitter
Magnesium Sleep, Muscle Relaxation, Energy Essential mineral; supports 300+ reactions
L-Theanine Calm Focus, Relaxation Amino acid; non-sedating; works fast

Glycine is often stacked with Magnesium and L-Theanine for comprehensive sleep support.

Popular Stacks with Glycine
Sleep Stack
Glycine + Magnesium Glycinate + L-Theanine
Most popular evening sleep combination
Recovery Stack
Glycine + Collagen + Tart Cherry
Great for post-exercise recovery
Calm Focus Stack
Glycine + L-Theanine + Apigenin
Popular for winding down

Full stack recommendations coming soon in our Stacks section.

Frequently Asked Questions
How long until I feel effects on sleep?
Most people notice improvements in sleep quality within 3–7 days of consistent use. Some report benefits on the first night.
Will glycine make me sleepy during the day?
No. Glycine promotes calm relaxation without sedation. It actually improves next-day alertness and cognitive function according to research.
Can I take glycine with other sleep supplements?
Yes. Glycine stacks very well with Magnesium, L-Theanine, Apigenin, and Tart Cherry. It is a common ingredient in comprehensive sleep formulas.
Sources & References

1. Bannai M, Kawai N (2012). New therapeutic strategy for amino acid medicine: glycine improves the quality of sleep. Front Neurol, 3, 61.

2. Inagawa K et al. (2006). Subjective effects of glycine ingestion before the sleep period on sleep quality. Sleep Biol Rhythms, 4(1), 75–77.

3. Razak MA et al. (2017). Multifarious beneficial effect of nonessential amino acid, glycine: a review. Oxid Med Cell Longev, 2017, 1716701.

All references are peer-reviewed studies or position stands from reputable organizations.

Related Ingredients
Magnesium
Sleep support pairing
5-HTP
Sleep and mood support
Collagen
Shared amino acid
TMG
Methylation support
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