Glycine & Melatonin: Should You Take These Sleep Aids?

Glycine is an amino acid (protein) and neurotransmitter. Melatonin is a hormone. In healthy persons with adequate nutrition, both are produced in adequate amounts by the body.

What are the claimed benefits?


  • Supports restful sleep

  • Improves symptoms of fatigue

  • Improves cognition

  • Supports liver health

  • Protects against age-related muscle loss

  • Supports blood sugar management for Diabetics

  • Cardio-protective

  • Generates antioxidants


  • Improves ease of falling asleep

  • Supports eye health

  • Supports gastrointestinal health

  • Improves immune system

  • Reduces cancer risk

What the science says

Glycine is an amino acid that, under normal conditions, is made by the body in sufficient quantities from other amino acids (proteins), namely serine, choline and threonine. In addition to working in concert with other proteins as building blocks for muscles, bones, antioxidant molecules and healthy tissues, it is a neurotransmitter that is both excitatory and inhibitory. Glycine plays an important role in exciting the brain for daytime cognitive performance, as well as calming the brain for restful sleep and memory formation.

Some research has shown that glycine supplementation subjectively improves daytime fatigue and cognitive performance. Additionally, glycine’s activity on NMDA receptors in the brain that regulate circadian rhythm has been clearly demonstrated. This signaling activation is responsible for increasing blood flow to the skin, thereby decreasing core body temperature - a normal function and trigger for inducing and maintaining deeper sleep throughout the night.

Melatonin is a hormone secreted by the pineal gland in your brain in response to darkness. Its production is inhibited by exposure to any light, especially blue light. It regulates the sleep-wake cycle although research is not conclusive on exactly how. Proposed mechanisms include the inhibitory functions on brain nerve activity, regulation of body temperature, and impact on other hormones such as HGH (human growth hormone).

Melatonin production sites and receptors have also been identified in the gastrointestinal tract, reproductive organs, and in skin, bone marrow and immune systems cells such as lymphocytes. While much is still unknown about melatonin, mounting evidence points to the protective benefits of normal melatonin cycles and the reduced risk for breast, prostate, skin, stomach, colon and potentially other cancers. Likely mechanisms are its role as a potent antioxidant, as an anti-inflammatory agent and a regulator of apoptosis - a process of cell death that helps rid the body of pre-cancerous or damaged cells before they accumulate and become a tumor.

Additionally, melatonin can increase esophageal sphincter tone, keeping it closed so that stomach acids stay out of the esophagus, reducing gastroesophageal reflux symptoms (aka heartburn). Several studies have compared melatonin supplements to omeprazole or other proton pump inhibitor (PPI) pharmaceuticals. Melatonin often wins, but without the negative effects that PPI’s can have such as causing deficiencies in B12, vitamin C, calcium, magnesium and iron which have adverse impacts on bone, brain, cardiovascular and overall health.

The Apeiron Life perspective

Sleep hygiene and lifestyle habits are still the top strategies for supporting sleep quantity and quality. Refer to the Apeiron Life Foundation Plan for additional details.

Additional notes:

  • Get adequate protein from your diet in order for your body to make glycine. A balanced Mediterranean diet provides adequate protein.

  • Support your body’s own ability to make melatonin through sleep hygiene practices, paying particular attention to getting enough daylight during the first half of the day and reducing your light exposure in the 2-3 hours before sleep.

Work with your Client Advocate and the Apeiron Life team to identify and prioritize strategies to support your unique goals and health.

Will a supplement benefit you?


As the name implies, a supplement is intended to supplement a healthy lifestyle that includes sleep hygiene, physical activity, stress management and balanced nutrition. Supplements are not replacements for these behaviors. More and more research is emerging every day about the complexities of the human body. To date, we simply don’t know enough to understand the right combination of supplements to replace the behaviors that have kept our species thriving for millenia. As research often pans out over the decades, endogenous or internally made compounds, versus exogenous or externally made supplements are usually found to be most beneficial over a lifetime.

Additionally, some consequences of supplements are known, but many are not yet known. Since safety does not have to be shown before a supplement can go to market, the risk is placed on the consumer. This risk is especially true when many supplements are combined in infinitely variable combinations outside of the research lab - aka real life. Hence, a healthy lifestyle is usually a safer bet for increasing healthspan and mitigating risk than handfuls of supplements.

Still curious to try a supplement?

All of that said, we fully recognize the need for short-term and occasional supplemental support while you work to adjust your habits over time.

Keep in mind:

Melatonin supplements show the best support for those who have trouble falling asleep.

  • Start with 0.5-1 mg 1 hour before bed.

  • Use 1-3 mg at target destination bedtime for jet lag prevention when crossing time zones.

Glycine supplements have stronger indications for those who wake frequently or have difficulty getting back to sleep.

  • Start with 1 g/night, increasing to 3 g/night as needed.

It is not recommended for you to take both glycine and melatonin. Choose one. Try it for 1 month. Notice the impacts (if any) before re-evaluating.

More reading & research



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