The link between the amino acid glycine and how it can improve our sleep was initially found completely by accident.
And the studies since then have shown us how we can best use glycine to improve our sleep.
Table of Contents
- Glycine
- How Glycine Affects Sleep
- Glycine and Human Studies
- Glycine for Sleep: Dosage and Use
- Other Potential Benefits of Glycine
- Four Keys to Better Sleep
- Melatonin and Magnesium for Sleep
- References
Glycine
Glycine was first discovered back in 1820 by a French chemist. He isolated it from animal collagen. It tasted sweet, which is how it got its name. It comes from the same Greek word meaning “sweet.”
It wasn’t until the 1900s that we understood more about proteins and their building blocks, amino acids. Glycine is one of the simplest. And it plays diverse roles in the body, from helping to build collagen to regulating inflammation.
Because of its taste, it has found many uses in the food industry. But more recently, researchers have been investigating its medical applications. And this is how the link to sleep was accidentally discovered.
Glycine is sometimes used as a control in studies looking at the effects of amino acid supplements. That’s because it’s considered biologically neutral. In other words, its effects on the body were thought to be minor. But during one experiment, researchers noticed those getting the glycine placebo had unexpected changes. And these changes pointed toward a possible impact on sleep.
How Glycine Affects Sleep
Researchers followed up that discovery by looking at glycine’s effects in rats. They noticed that oral doses of glycine significantly increased glycine levels in brain fluid and tissue.
Within the brain, glycine acts on certain receptors within the suprachiasmatic nucleus, or SCN. The SCN is essentially the body’s master clock. It controls the circadian rhythm that tells the body when it’s time to be awake and when it’s time to sleep.
And what is the impact of glycine in this area? It signals the blood vessels to dilate. This, in turn, helps the body lose heat, lowering body temperature. A drop in body temperature is a central part of the circadian shift into sleep.
Glycine and Human Studies
So what is the actual impact on sleep in humans?
A small, double-blind study published in 2006 investigated this question. Participants took either a placebo or glycine before bed. The next morning, they filled out a questionnaire. Glycine supplements significantly improved their ratings of liveliness and clear-headedness. They also reduced their feelings of fatigue.
A similar study added objective sleep measurements. Participants taking glycine fell asleep and reached deep sleep faster. They reported better sleep, less daytime sleepiness, and performed better on memory tests the next day.
One crucial observation: glycine didn’t change sleep architecture. That means the normal sleep stages remained intact. This matters because many sleep medications disrupt these stages, often leaving people groggy the next day.
A third study restricted participants’ sleep by 25% for three nights in a row. Those who took glycine reported less fatigue and sleepiness during the day.
Another investigation found that glycine also helped people with overactive bladder fall asleep faster, suggesting another benefit of the amino acid.
Glycine for Sleep: Dosage and Use
If we want to add glycine to our sleep routine, what’s the right way to approach it?
The sleep studies used a dose of 3,000 mg, taken shortly before bedtime.
I personally take glycine as part of my Sleep supplement. It has 2,500 mg of glycine on its own, and an additional 774 mg of glycine from magnesium glycinate, totaling just over 3,200 mg of glycine.
But just because I take a supplement does not in any way mean that you should as well.
For me, I take glycine because of this research on sleep. But there are other areas attracting attention for potential benefits.
Other Potential Benefits of Glycine
Metabolic Health
One study tested glycine in individuals at higher risk for type 2 diabetes. It found that glycine boosted insulin production after meals, helping process food more effectively.
Another study looked at people with metabolic syndrome. Glycine supplementation for 3 months reduced markers of oxidative stress, a key contributor to aging and chronic disease.
Blood pressure also fell for men in the treatment group, which is good news for heart health.
Inflammation
Glycine helps reduce chronic low-level inflammation, common in obesity and diabetes. It decreases pro-inflammatory markers and boosts anti-inflammatory ones.
Schizophrenia
One study explored glycine as an add-on to common antipsychotic medications. It resulted in a 23% reduction in negative symptoms.
Longevity
Glycine was tested in rodents through the Interventions Testing Program. It led to a 4–6% increase in lifespan on average. Whether that applies to humans is still unknown, but the results are promising.
Still, for me, glycine is about sleep. The impact is real, though modest. For truly great sleep, we also need to get four other key elements right.
Four Keys to Better Sleep
1. Morning Light
A European study found that more time outdoors led to earlier bedtimes. Other studies show that daylight exposure increases sleep duration and quality.
It’s all about circadian rhythms. Light—especially blue light from morning sun—signals our body clock through receptors in the eye.
2. Exercise
Exercise helps regulate circadian rhythms and improves sleep quality.
3. Coffee Timing
One study found caffeine should be consumed at least 8.8 hours before bedtime to avoid disrupting sleep.
I aim to have my last coffee within 4 hours of waking.
4. Early, Light Dinner
Heavy meals close to bedtime can interfere with falling asleep. A study linked later dinners to longer sleep latency—meaning it takes longer to fall asleep.
Melatonin and Magnesium for Sleep
Melatonin
Melatonin signals the body it’s time to sleep. A meta-analysis of 14 studies found melatonin reduced the time to fall asleep. Another review showed improved sleep quality.
However, the dose matters. The body naturally produces 10–80 micrograms. About 15% of a melatonin supplement is absorbed.
That’s why I include 300 micrograms in my Sleep supplement—enough to mimic what the body makes naturally. For best results, take melatonin 2 hours before bed.
Magnesium
A 2024 meta-analysis found that magnesium supplements improved at least one aspect of sleep in 5 out of 8 randomized controlled trials.
But again, that doesn’t mean you need to take a supplement. Personally, I’ve achieved the best sleep when I combine:
- Morning light
- Exercise
- Early coffee
- Early, light dinner
- And glycine, melatonin, and magnesium as support
References
1. https://www.sciencedirect.com/science/article/pii/S1347861319305729
2. https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1479-8425.2006.00193.x
3. https://onlinelibrary.wiley.com/doi/full/10.1111/j.1479-8425.2007.00262.x
4. https://pmc.ncbi.nlm.nih.gov/articles/PMC3328957/
5. https://www.degruyterbrill.com/document/doi/10.1515/jcim-2020-0282/html
6. https://pubmed.ncbi.nlm.nih.gov/11456285/
7. https://pubmed.ncbi.nlm.nih.gov/24144057/
8. https://pmc.ncbi.nlm.nih.gov/articles/PMC10379184/
9. https://pubmed.ncbi.nlm.nih.gov/14732596/
10. https://pmc.ncbi.nlm.nih.gov/articles/PMC6516426/
11. https://journals.sagepub.com/doi/10.1177/0748730402239679
12. https://pmc.ncbi.nlm.nih.gov/articles/PMC6751071/
13. https://pubmed.ncbi.nlm.nih.gov/36870101/
14. https://www.mdpi.com/2674-0311/2/2/11
15. https://www.sciencedirect.com/science/article/abs/pii/S0022395619309872?via%3Dihub
16. https://pubmed.ncbi.nlm.nih.gov/33417003/
17. https://pmc.ncbi.nlm.nih.gov/articles/PMC4138917
18. https://pubmed.ncbi.nlm.nih.gov/10883420/
19. https://pubmed.ncbi.nlm.nih.gov/38817505/
