Glycine is a small but mighty amino acid involved in everything from collagen and antioxidant production to nervous system function. And increasingly, it’s gaining attention for its potential sleep benefits and its growing use in sleep supplements.

So, what exactly is glycine, what does it do, and why might taking glycine for sleep be worth considering? Here’s what to know.

What Is Glycine?

Glycine is a non-essential amino acid, which means your body can produce it on its own. Glycine is also found naturally in protein-rich and collagen-rich foods such as meat.

But “non-essential” doesn’t mean unimportant. Glycine plays an important role in a wide range of processes throughout the body. It supports your body's production of compounds like collagen, creatine, and glutathione, and it also acts as a neurotransmitter in the nervous system.

What Are the Benefits of Glycine?

Glycine has recently gained attention for its sleep benefits, but the amino acid also has several other important benefits.

1. Glycine May Support Better Sleep

One of the most interesting glycine benefits is its role in sleep.

Research suggests that taking glycine before bed may help support better sleep quality. Several human studies have found improvements in overall sleep quality after taking glycine at night. In one study, taking 3 grams of glycine before bedtime improved subjective sleep quality and was associated with reduced daytime sleepiness and improvements in next-day memory performance.

One reason glycine may benefit sleep has to do with body temperature. Your core body temperature naturally begins to fall as you prepare for sleep, and this decline is part of the body's normal transition into sleep. Researchers suggest that it's possible glycine may support this process by increasing blood flow near the skin, helping the body release heat and lower its core temperature.

Glycine also interacts with receptors in the brain and nervous system involved in neurological signaling, providing another potential reason glycine helps regulate sleep.

2. Glycine May Help Reduce Daytime Fatigue After Poor Sleep

Your energy levels and cognitive performance during the day are an important indicator of how well you slept the night before.

Research on glycine for sleep suggests that its potential benefits may extend into the following day. In small studies, taking glycine before bed has been associated with reduced fatigue and improvements in certain measures of daytime alertness and cognitive performance.

3. Glycine Helps Make Creatine

Glycine is also involved in the body's natural production of creatine.

Glycine is one of the amino acids your body uses to make creatine. Creatine helps replenish energy in cells, especially during brief, high-intensity efforts, and it also has important roles in tissues with high energy demands.

4. Glycine Helps Support Collagen Production

Glycine is a major building block of collagen, the most abundant protein in the human body. Collagen is a key structural component in your skin, bones, cartilage, tendons, and other connective tissues. About one-third of collagen’s amino-acid residues are glycine, helping form the tightly packed structure of this protein.

5. Glycine Supports Your Body's Antioxidant Defenses

Glycine helps your body produce glutathione, one of its major naturally occurring antioxidants. And glutathione helps protect cells against oxidative stress.

Your body makes glutathione from three amino acids: glycine, cysteine, and glutamate. That makes glycine one of the building blocks your body uses to maintain its own antioxidant defense system.

How Does Glycine Help With Sleep?

Yes, existing research suggests that glycine may improve certain measures of sleep quality, including subjective sleep satisfaction, sleep efficiency, and time to fall asleep. Researchers are still working to fully understand the relationship, but there are a few potential mechanisms.

Glycine appears to influence the body's regulation of core temperature, helping promote the natural decrease in temperature associated with sleep. It also functions as a neurotransmitter and interacts with NMDA receptors, which are involved in signaling throughout the brain and nervous system.

Several small studies have found that 3 grams of glycine taken approximately 30 minutes to one hour before bed may improve certain measures of sleep quality and next-day tiredness and cognitive performance.

What Foods Contain Glycine?

Your body produces glycine naturally, but you also get it through your diet.

Some glycine-rich foods include:

• Bone broth
• Meat and poultry (especially connective tissue)
• Fish (particularly with the skin on)
  
• Gelatin
  
• Collagen-rich cuts of meat
• Seeds (pumpkin seeds, chia seeds, and sunflower seeds)
• Legumes

Collagen is especially rich in glycine, so foods containing connective tissue and gelatin tend to provide higher levels of glycine.

Glycine is also available as a standalone supplement and as an ingredient in some sleep-support formulas such as Modern Dose's Sleep Aid. 

When Should You Take Glycine for Sleep?

Studies investigating glycine for sleep benefits have commonly used 3 grams shortly before bedtime, often around 30 minutes to one hour before going to sleep.

Does Glycine Make You Sleepy?

Glycine does not cause immediate drowsiness or act as a sedative, but it does support natural sleep. Rather than simply "knocking you out," glycine is being studied for its ability to support the body's natural transition into restful sleep.

Should I Take a Glycine Supplement?

Supplementation needs vary from person to person, but glycine may be worth considering if you're looking for additional sleep support.

Glycine's potential sleep benefits are particularly promising. Early human research suggests that taking 3 grams of glycine before bed may support sleep quality while helping reduce feelings of fatigue and sleepiness the following day.

Beyond sleep, glycine contributes to collagen and creatine production, helps your body make the antioxidant glutathione, and participates in nervous system signaling.

When choosing a glycine supplement, look for a product from a reputable brand that clearly discloses the amount of glycine per serving. Modern Dose's Sleep Aid drink mix contains 3 grams of glycine per serving; the same amount used in several human studies examining glycine and sleep.

As with any supplement, it's a good idea to follow product directions and talk with a healthcare professional if you have a medical condition, take medications, are pregnant or breastfeeding, or have questions about whether a supplement is appropriate for you.

In Summary

Glycine is a non-essential amino acid with benefits that extend throughout the body. The amino acid is becoming increasingly popular for its sleep benefits, but it also helps support collagen production, antioxidant defenses, creatine synthesis, and normal nervous system function. 

For anyone looking to build a better nighttime routine, glycine is one sleep-supporting ingredient worth knowing.