Glycine
Amino acid that supports sleep onset and quality at 3 g before bed.
What the evidence says
Small RCTs show improved subjective sleep quality and next-day alertness at 3 g pre-bed.
How it works
Glycine is a non-essential amino acid that acts as an inhibitory neurotransmitter in the central nervous system. When taken before sleep, it may help lower core body temperature by increasing blood flow to the extremities, which is a physiological signal for the body to initiate sleep. It also interacts with NMDA receptors in the brain, which may modulate circadian rhythms.
What you may get out of it
Sleep Quality
Glycine may improve the subjective experience of sleep depth and restfulness, helping individuals feel more restored upon waking.
Daytime Alertness
By improving sleep efficiency, glycine is associated with reduced daytime sleepiness and better performance on cognitive tasks the following day.
Body Temperature Regulation
It supports the natural nocturnal cooling process of the body, which can shorten the time it takes to fall asleep.
What the research consistently shows
Sleep Onset and Quality
Clinical trials involving individuals with self-reported sleep dissatisfaction suggest that glycine supplementation can improve sleep architecture. Participants often report falling asleep faster and reaching deep sleep stages more efficiently compared to placebo groups.
Cognitive Performance
Research observing the morning-after effects of glycine indicates that users often experience less brain fog and improved reaction times. This is generally attributed to the higher quality of the preceding night's sleep rather than a direct stimulant effect.
How to take it
A common approach is taking glycine in powder or capsule form approximately 30 to 60 minutes before bed. It has a naturally sweet taste and can be dissolved in water or a decaffeinated tea. Taking it consistently at the same time every evening may help reinforce the body's sleep-wake cycle.
Realistic expectations
While some individuals notice a difference in sleep quality within the first few nights, it typically takes one to two weeks of consistent use to assess the full impact on daytime alertness. It is most effective for those experiencing occasional sleep stability issues rather than chronic clinical insomnia.
What it doesn't do
Glycine is not a sedative or a hypnotic drug; it will not force sleep if external factors like high caffeine intake or blue light exposure are present. Evidence is currently limited regarding its long-term use over many years, and it should not be used as a primary treatment for sleep apnea or other underlying medical sleep disorders.
This information is for educational purposes only and does not constitute medical advice or a recommendation for treatment. Synthesized by AI from established research on this category, with no fabricated citations or statistics.
⚕ This is general wellness information, not medical advice. It does not replace consultation with a healthcare professional. If you take prescription medication, are pregnant, or have a medical condition, talk to your doctor before starting new supplements.