Weak evidence · Sleep & stress
Glycine
Sleep quality after a short night
Weak evidence
Mostly small studies, animal trials or conflicting results. Not worth your money as a foundation.
In studies glycine slightly lowers core temperature before sleep. In small studies, including one with only seven participants who slept shorter for three nights, 3 g improved perceived sleep quality and reduced daytime sleepiness. In a small polysomnographic study it stabilised sleep and shortened the time to deep sleep. The evidence is thin.
- Dosage
- 3 g
- Timing
- About 30 to 60 minutes before bed
- Approx. price
- €4–8 per month
Watch out
In the small studies 3 g caused no side effects. Effects with long-term use and in larger groups are not yet sufficiently studied.
Frequently asked questions about supplements
How much Glycine per day?
3 g
When should you take Glycine?
About 30 to 60 minutes before bed
Does Glycine really work?
Weak evidence. Mostly small studies, animal trials or conflicting results. Not worth your money as a foundation.
What does Glycine cost?
€4–8 per month
Basics first, then the tub
Supplements are called supplements because they add to something. Sleep, a protein intake that hits your protein calculator , a programme where you lift progressively heavier and enough food together do a hundred times more than the best-researched item on this list. Once those are in place, creatine, caffeine and vitamin D in winter are the three you can spend money on with a clear conscience — for less than ten euros a month combined.
Sources
- Bannai M et al. (2012). The effects of glycine on subjective daytime performance in partially sleep-restricted healthy volunteers. Front Neurol 3:61. (small randomized crossover trial, n = 7)
- Yamadera W et al. (2007). Glycine ingestion improves subjective sleep quality in human volunteers, correlating with polysomnographic changes. Sleep Biol Rhythms. (small trial)
More supplements in this category
Last updated: October 2026
This page summarises scientific research and is not medical advice. If you take medication, are pregnant or have a liver, kidney or thyroid condition, discuss supplements with your doctor or pharmacist — even the innocent-looking ones.
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