When should I take glycine, morning or night? The definitive timing guide

December 2, 2025 •

4 min read

Sleep problems affect about a third of adults in Western countries at least once a week, making natural aids like glycine a popular topic of discussion. A crucial question for those considering it is when should I take glycine, morning or night?, as the answer depends on your primary wellness goals.

Quick Summary

Optimal glycine timing depends on wellness goals. Take at night for improved sleep, or in the morning for metabolic support like better insulin response.

Key Points

Nighttime is Optimal for Sleep: Taking a specific amount of glycine 30-60 minutes before bed can help lower core body temperature and calm the nervous system, promoting deeper, higher-quality sleep.
Daytime Glycine Won't Cause Drowsiness: Research shows that taking glycine during the day does not induce sleepiness, allowing for flexibility in timing for other health benefits.
Morning Dose for Metabolic Health: A morning intake of glycine may help improve insulin response, supporting better blood sugar regulation throughout the day.
Enjoy Next-Day Benefits from Nighttime Dose: Better sleep from a nighttime dose translates to reduced daytime fatigue, increased alertness, and improved cognitive performance the following day.
Consistency is Key: Taking glycine nightly for a week or more is recommended to see consistent improvements in sleep quality and next-day energy levels.

Understanding Glycine's Dual Role

Glycine is a non-essential amino acid, meaning the body can produce it, but it also comes from protein-rich foods and supplements. It plays a role in synthesizing key compounds like collagen and glutathione, but also acts as a neurotransmitter in the central nervous system. This dual function is why the timing of your dose is so important—it dictates which benefits you emphasize.

The Proven Case for Nighttime Glycine

Overwhelming research points to taking glycine before bed for improving sleep. Clinical studies have shown that taking a specific amount 30 to 60 minutes prior to sleep can significantly improve sleep quality and reduce daytime sleepiness. This is especially true for individuals who report having unsatisfactory sleep. The nighttime effects are driven by several key mechanisms:

Lowering Core Body Temperature: Glycine acts on receptors in the brain's suprachiasmatic nucleus (SCN), the body's internal clock, to increase blood flow to the skin. This peripheral vasodilation helps dissipate heat, lowering your core body temperature and signaling the body that it's time for sleep.
Promoting Deeper Sleep: Studies using polysomnography (a gold-standard sleep measurement) confirm that glycine reduces the time it takes to enter deep, slow-wave sleep. This leads to more efficient and restorative rest.
Calming Neurotransmitter Activity: Functioning as an inhibitory neurotransmitter, glycine calms the central nervous system. It binds to glycine receptors to inhibit neuron firing, helping the mind to relax and become less responsive to sleep-disrupting stimuli.

Daytime Benefits from a Nighttime Dose

Interestingly, the positive effects of a nighttime glycine dose don't stop when you wake up. The improved sleep quality directly translates into better next-day performance.

Reduced Daytime Fatigue: People who take glycine before bed report feeling less fatigued and more refreshed upon waking, even if their sleep duration was limited.
Enhanced Cognitive Function: Research shows a glycine dose before bed can improve memory recognition tasks and overall cognitive performance the following day. This means a clearer, more focused mind throughout the day.

The Emerging Case for Morning Glycine

While less studied than its sleep-promoting effects, there is some evidence supporting morning glycine intake for specific goals. Importantly, taking glycine during the day does not cause drowsiness.

Improved Insulin Sensitivity: A study involving people at risk for type 2 diabetes found that taking glycine in the morning improved insulin secretion throughout the day. This makes morning intake potentially beneficial for blood sugar management.
Creatine Production and Energy: Glycine is a precursor to creatine, a compound that supplies muscles and the brain with energy for quick, short bursts of activity. Taking it in the morning could help support creatine production for daytime energy and mental function.
Glutathione Synthesis: Glycine is a rate-limiting amino acid for the production of glutathione, a powerful antioxidant. Spacing out doses, including a morning dose, can help support glutathione levels throughout the day.

Practical Supplementation Tips

Regardless of your timing, here are some helpful guidelines:

Consult a Healthcare Professional: Discuss the appropriate amount for your individual needs with a healthcare provider.
Consistency is Key: For sleep benefits, taking glycine nightly can help achieve cumulative effects over several weeks.
Form: Glycine is available in powder or capsule form. The powder dissolves easily in water, is naturally sweet, and is absorbed more quickly, often within 20 minutes.
Empty Stomach: For better absorption, consider taking your dose on an empty stomach, especially for the sleep-focused regimen.

Glycine Timing: Morning vs. Night


Timing	Primary Goal	Key Benefits
Night (30-60 min before bed)	Improve sleep quality and reduce daytime fatigue.	• Lowers core body temperature • Calms nervous system • Enhances deep sleep stages • Improves next-day cognition
Morning	Improve insulin response and support energy metabolism.	• Aids blood sugar management • Supports creatine production • Boosts antioxidant capacity • No daytime drowsiness

Conclusion: Tailoring Your Glycine Schedule

So, when should I take glycine, morning or night? The answer depends on your primary wellness objective. If your main goal is to improve sleep quality, reduce nighttime restlessness, and feel more refreshed during the day, taking glycine about 30-60 minutes before bed, in an amount recommended by a healthcare professional, is supported by research. However, if you are focusing on metabolic health like insulin sensitivity or supporting energy metabolism throughout the day, a morning dose can be a valid approach. For comprehensive health support, some people may choose to take a moderate amount both morning and night, following professional guidance. Before starting any new supplement, especially if you have pre-existing health conditions or take other medications, it is always best to consult with a healthcare professional.

One study gave three grams of glycine to humans who were sleep-restricted to 25% less than their normal sleep for three nights.

Frequently Asked Questions

For improved sleep quality, taking glycine 30 to 60 minutes before bedtime is often recommended. This timing allows the supplement to begin its effects, such as lowering core body temperature, as you prepare for sleep.

Yes, you can take glycine in the morning. It will not cause daytime drowsiness. A morning dose may be more beneficial if your primary goal is to improve insulin sensitivity or support creatine production for energy.

The appropriate amount of glycine can vary depending on individual needs and goals. For sleep improvement, some studies have used specific amounts that showed positive results. It is always recommended to consult with a healthcare professional to determine the right amount for you.

Some individuals report feeling a difference within the first few nights, noticing faster sleep onset. However, the full benefits of consistent, high-quality sleep and reduced daytime fatigue may take up to two weeks to become fully apparent.

Both forms are effective, but powder dissolved in water is absorbed more quickly, sometimes within 20 minutes. Capsules may take slightly longer to absorb, but the difference is minimal for long-term use. Your choice depends on personal preference.

Glycine is generally well-tolerated and considered safe. Some individuals may experience mild gastrointestinal discomfort, such as soft stools. It's best to start with a smaller amount to see how your body reacts.

Glycine can be found in protein-rich foods, particularly tough cuts of meat like brisket and chuck, and in bone broth. Other good sources include gelatin, fish, and legumes, though a supplement offers a more concentrated amount for potential effects.