Ray Peat on Glycine for Sleep: How Much to Take Before Bed
Glycine supports restful sleep and a fresher next morning: in human studies, 3 grams before bed went with better-feeling sleep and less next-day fatigue. A simple way to get there is to start with one level scoop of Glycine Powder USP Grade (about 1 g) in water or tea in the evening, then add a scoop every few days, up to about 3 g, to support restful sleep.
How much glycine should you take before bed?
The human studies used 3 g before bed, but you don’t have to start there. Here’s the gentle method from our product page:
- Start: 1 level scoop (about 1 g) in the evening, mixed in water or any drink.
- Notice: give it a few days and pay attention to how you sleep and how you feel the next morning.
- Raise slowly: if you want more, add one scoop every few days, up to 3 scoops a day (about 3 g).
For exact grams, a precision digital scale takes out the guesswork.
When should you take glycine for sleep?
Take it in the evening or shortly before bed, as people did in the studies. Glycine is naturally sweet and dissolves easily, so it fits into an evening cup of tea, water, milk, or juice. If you also take it during the day, start with one scoop and see how you feel. Some people find it relaxing.
What the research shows
Here’s what people got in human studies of glycine:
- Better-feeling sleep. People who weren’t satisfied with their sleep rated it better after 3 g before bed.
- A fresher next day. After short nights, healthy adults had less fatigue, a trend toward less sleepiness, and better scores on an alertness test.
- Consistent results, small studies. Two reviews of the research found glycine linked to better sleep. One found a benefit in all 3 glycine sleep trials it covered. Both noted the trials were small.
What about calm? Many people describe glycine as relaxing in the evening, but the studies measured sleep and next-day feel, not calm itself, so we won’t claim more.
Here are the studies behind those points.
Researchers in Japan ran small human trials with people who weren’t satisfied with their sleep. They gave 3 g of glycine or a placebo before bed. A 2012 review of that work reports that glycine before bed improved how well people felt they slept (Bannai & Kawai, 2012, J Pharmacol Sci, PubMed 22293292).
A separate study in healthy adults whose sleep was cut short found that 3 g of glycine at bedtime was linked to less fatigue the next day, a trend toward less sleepiness, and better scores on an alertness test (Bannai et al., 2012, Front Neurol, PubMed 22529837).
Why might it help? In an animal study (rats, not people), glycine lowered core body temperature, a natural part of falling asleep (Kawai et al., 2015, Neuropsychopharmacology, PubMed 25533534).
A 2024 systematic review pulled together glycine research in adults. It found that glycine was linked to better sleep in healthy people, and it noted that those studies were small and had a high risk of bias, so larger, better-designed studies are needed (Soh et al., 2024, Geroscience, PubMed 37851316).
A 2026 scoping review found 3 trials of glycine and sleep, and all 3 reported a benefit on at least one sleep-related outcome. It also found that glycine supplements raise glycine levels in the blood. The authors called for larger trials (Fan et al., 2026, J Diet Suppl, PubMed 42687500).
These were small studies, and everyone is different. Glycine is a simple way to support restful sleep, not a sleep medication.
Glycine powder vs capsules: which is easier at 3 g?
Powder, by a wide margin. Three grams takes a lot of capsules but only three small scoops of powder. Powder also lets you start at 1 g and build up in single-scoop steps.
What does “USP Grade, 99.5% pure” mean?
USP Grade means the glycine meets United States Pharmacopeia standards. Ours is 99.5% pure, made in the USA, and one ingredient, with no fillers or additives. The product page links our Typical Certificate of Analysis, and every bag includes a scoop.
The bioenergetic view of glycine
Glycine is the most common amino acid in gelatin, the cooked form of collagen. About one in every three amino acids in collagen is glycine. Traditional nose-to-tail eating included plenty of gelatin-rich foods like skin, bone broth, and connective tissue, while a modern, muscle-meat-heavy diet includes far less. That’s why many people in the bioenergetic community add glycine or gelatin to balance a meat-heavy diet.
Ray Peat wrote about glycine in several of his articles. In “Glucose and sucrose for diabetes” he wrote:
“Glycine, like carbon dioxide, protects proteins against oxidative damage (Lezcano, et al., 2006), so including gelatin (very rich in glycine) in the diet is probably protective.”
— Ray Peat, raypeat.com/articles/articles/glucose-sucrose-diabetes.shtml
His longer article “Gelatin, stress, longevity” covers glycine and gelatin in depth for anyone who wants to read his reasoning directly. (The Lezcano study he mentions, Lezcano 2006, Rev Alerg Mex, PMID 17361755, was an animal study, so we don’t rely on it here.)
What goes well with glycine in the evening?
Glycine pairs well with Taurine USP Grade or Magnesium Chloride Capsules as part of a calm evening routine.
Daylight matters too. In a field study of healthy adults, people whose first exposure to more than dim light (about 10 lux) came later in the day woke up more often that night. Getting outside early is an easy habit to try (human observational study; PMID 29040758). Ray Peat cited this study in his March 2018 newsletter, “Sleep and Aging.”
Glycine Powder USP Grade comes in 250 g and 1000 g bags, each with a scoop, and every order has 60-day no hassle returns.
Start with a 250 g bag of glycine powder →
Frequently asked questions
How much glycine should I take for sleep?
The human sleep studies used 3 g before bed. Start with one level scoop (about 1 g), then add one scoop every few days, up to 3 scoops (about 3 g). A precision digital scale helps if you want exact grams.
When should I take it?
In the evening or before bed, mixed in water, tea, or any drink. If you take it during the day, start with one scoop and see how you feel.
Is powder better than capsules?
At 3 g, powder is simpler. It’s a few small scoops instead of a handful of capsules. It’s naturally sweet and dissolves easily.
What’s in it?
Only glycine. It’s USP Grade, 99.5% pure, made in the USA, with no fillers or additives.
Can I take glycine every night?
The human sleep studies used 3 g before bed. Glycine is also a normal part of food, especially gelatin. Talk with your healthcare provider if you take medications or have a health condition.
Can I return it?
Yes. Every order comes with 60-day no hassle returns.
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.
