Having trouble falling asleep? Feeling exhausted when your alarm goes off in the morning? You’re not alone. According to the Centers for Disease Control (CDC), an estimated 83.6 million U.S. adults get less than 7 hours of sleep each night, whether due to insomnia, shift work, sleep apnea, pain, or poor sleep hygiene (1). While most sleep specialists recommend a number of behavior changes to remedy sleep problems, those changes don’t always work for everyone.
The American Academy of Sleep Medicine (AASM) reports that up to 50 percent of American adults have some form of insomnia, with between 10 and 15 percent resulting in ill effects such as daytime sleepiness or forgetfulness. Sleep is an essential human function, just like eating and breathing, so finding a solution for insomnia is critical, not only for your emotional well-being, but for your physical health as well.
An amino acid called glycine could be the natural solution you’re looking for. It’s the most prevalent amino acid in the body and can work as both an excitatory and inhibitory compound (a.k.a. stimulating and calming). Studies are showing incredible results when using it as a natural remedy for sleep disorders like insomnia. Let’s explore the science behind glycine’s powerful calming effects and why it might be the best option for a natural sleep aid.
What Is Glycine?
Glycine is the most prevalent amino acid in the human body and is considered the most important as well. We can produce it on our own (non-essential amino acid) with other biochemicals like serine, choline, and threonine. We’re focusing on sleep today, but glycine is such a crucial ingredient in so many processes in your body that we’ve dedicated a whole post to covering all the important functions it helps perform.
As a quick summary, it’s one of the body’s main building blocks for making collagen and creatine, both critical ingredients in building healthy muscle along with various other important body functions and tissue. The brain also uses creatine for energy. Other biochemical processes for which glycine is needed include:
- Regulating the body’s immune response
- Affecting cognition and mood
- Mediating appetite and digestion
- Perceiving and managing pain
- Production of RNA and DNA
- Sleep regulation (2)
Glycine is also a powerful neurotransmitter that helps the body produce serotonin, the “happy neurotransmitter” found primarily in your brain and gut. Serotonin is a key ingredient in the production of melatonin, and melatonin is critical for a good night’s sleep.
Dietary glycine is a normal part of an omnivorous diet, found in meat, eggs, dairy, and fish, in addition to vegetarian sources like banana, kiwi, spinach, pumpkin, and cruciferous vegetables (kale, cauliflower, cabbage). The most potent sources of dietary glycine are bone broth and collagen powder.
But sometime diet alone isn’t enough, especially right before bedtime. That’s where a sleep-promoting glycine supplement comes in.
The Problem With Over-the-Counter and Prescription Sleep Solutions
The central nervous system is a complex and complicated system of neurotransmitters, receptors, nerves, and synapses. While sleep research continues to uncover the science behind why we sleep, we can all agree that better sleep quality means better life quality.
Night after night of poor sleep can lead you down a desperate rabbit hole of neuropsychopharmacology solutions, but these Band-Aid drugs aren’t free of side effects. Benzodiazepines like Valium or Xanax (considered anti-anxiety hypnotics) might help you fall asleep, but they actually alter your sleep patterns, changing the normal proportions of deep sleep, slow-wave sleep, and REM sleep, and leaving you groggy with potentially delayed recall (anterograde amnesia) in the morning. They’re also highly habit-forming.
OTC solutions like diphenhydramine (ZzzQuil and Benadryl) might seem harmless, but they’re also addictive and come with their own set of withdrawal symptoms (including nausea, fast heart rate and blood pressure, anxiety, muscle weakness, and dry mouth, just to name a few) (3). Other more serious complications include a higher risk for dementia after long-term use (4).
Prescription sleep aids that may be less habit-forming than benzos like Lunesta and Ambien come with their own sets of potential side effects, including:
- Burning or tingling in the hands, arms, feet, or legs
- Stomach pain or tenderness
- Changes in appetite
- Uncontrollable shaking of a part of the body
- Difficulty keeping balance
- Daytime drowsiness
- Impairment the next day
- Dry mouth or throat
- Mental slowing or problems with attention or memory
- Unusual dreams
- Weakness (5)
In addition to this long list, less common adverse effects include sleep walking and carrying on with day-to-day life activities while still asleep. This is why they have warnings about not operating heavy machinery until you know how the medication will affect you.
What the Research Shows
Glycine treatment for sleep disorders has consistently shown to not only help human volunteers fall asleep more quickly, but also increase sleep efficiency, reduce insomnia symptoms, and promote deeper, more restful sleep (2).
One small study by Japanese researchers measured both subjective and objective sleep quality after ingesting either a placebo or 3 grams of glycine. Overwhelmingly, glycine helped shorten the time it took to fall asleep and improved sleep satisfaction and sleep quality, in both subjective and objective measures. And all of these effects were measured without any observable disruption in sleep patterns or architecture (6).
Another important study measured the effects of glycine on human subjects after intentionally inflicting sleep deprivation by 25 percent for three nights. They also did a concurrent study on rats in order to study their brains as part of the experiment. Using either 3 grams of glycine or a placebo, researchers measured the difference in both objective and subjective daytime performance after the short sleep. They found that those who ingested the glycine performed better, despite the poor quality of sleep (7).
Glycine’s Action on Sleep
So why does glycine ingestion work? Not only does it improve sleep quality but it also impacts how rested you feel in the morning. How does it work?
We know that glycine is an important ingredient in the production of melatonin, the neurotransmitter that helps regulate your circadian rhythm (the sleep-wake cycle). But glycine also helps lower your core body temperature through NMDA receptors, a change that naturally occurs as you drift into the first stages of sleep (8).
As far as reducing feelings of grogginess and improving daytime performance, glycine is a key neurotransmitter in the hippocampus, the part of the brain responsible for memory and learning. As your hippocampus is bathing in glycine, not only are you getting a good night’s sleep, you’re also prepping your brain to wake up alert and ready in the morning. Interestingly, due to this action on the hippocampus, scientists are looking into the use of glycine to help treat Alzheimer’s and dementia patients (2).
How to Take Glycine
The studies that show glycine’s effectiveness have used 3 grams as their main dosage. Doctors recommend that you start at that dosage, or work up to it if you experience any digestive side effects. If 3 grams doesn’t work for you, you can slowly increase.
You might also find that glycine-containing collagen supplements work better for you. Dr. Chris Masterjohn reports that he has patients who prefer one over the other due to digestive side effects, but that the preference is totally unique to each individual. Same with the dosing. Masterjohn reports that his patients range in dosing free glycine anywhere from 3 grams all the way up to 6 grams, and that the collagen dosage varies from person to person as well (9).
However you dose your glycine, start small and work your way up to reduce the chances of any digestive reactions. Here’s to a good night’s sleep.