Glycine
Preliminary· human dataA simple amino acid with early evidence for sleep quality.
What it is
Glycine is a simple amino acid found in food, taken before bed for sleep quality. Unlike melatonin it is not a hormone and doesn't shift your body clock; the two work by different routes.
What the evidence shows
Sleep quality. Preliminary· human data A few small studies suggest taking glycine before bed can improve subjective sleep quality and reduce next-day tiredness, possibly by gently lowering core body temperature. Promising, but based on limited research.
Who it suits
People after a gentle, well-tolerated sleep aid who want something other than a hormone like melatonin.
Practical notes
Glycine is generally very well tolerated at the amounts studied. As with most sleep supplements, expectations should be modest — the foundations of good sleep matter more, and our sleep calculator helps you set a sensible schedule.
Sources
Frequently asked questions
- Does glycine improve sleep?
- A few small studies suggest taking glycine before bed can improve subjective sleep quality and reduce next-day tiredness, possibly by gently lowering core body temperature. It's promising but based on limited research.
- How does it differ from melatonin?
- Glycine isn't a hormone and doesn't shift your body clock; the proposed effect is on sleep quality and getting to sleep comfortably, rather than on sleep timing. The two work by different routes.
- Is it safe?
- Glycine is an amino acid found in food and is generally very well tolerated at the amounts studied. As with most sleep supplements, expectations should be modest.
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Written and reviewed by Mathew Beale — MSc Biotechnology, University of Reading.
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