Glycine is an amino acid and neurotransmitter that has gained significant attention as a natural sleep aid. Research shows that taking 3 grams of glycine before bed can lower core body temperature, increase serotonin levels, and help you fall asleep faster while improving overall sleep quality without next-day grogginess. Glycine supplements come in capsules and powder form, with powder offering the most cost-effective way to reach the studied 3-gram dose.
Quick Comparison
Product
Dose per Serving
Form
Best For
Rating
NOW Supplements Glycine Pure Powder
3,000mg
Powder
Best Overall
4.7/5
Life Extension Glycine
1,000mg
Capsules
Best Capsule
4.6/5
Double Wood Glycine
1,000mg
Capsules
Best Value Capsule
4.5/5
Thorne Glycine
1,000mg
Capsules
Best Practitioner-Grade
4.6/5
Micro Ingredients Glycine
2,000mg
Capsules
Best Double-Strength
4.5/5
Pure Encapsulations Glycine
500mg
Capsules
Best Premium
4.5/5
BulkSupplements Glycine Powder
3,000mg
Powder
Best Bulk Value
4.6/5
1. NOW Supplements Glycine Pure Powder – Best Overall
NOW Foods Supplements, Glycine Pure Powder, Promotes Restful Sleep*, Neurotransmitter Support*, 1-Pound
PURE POWDER/PROMOTES RESTFUL SLEEP*: Glycine is also a precursor of creatine, which is used to construct DNA and RNA*
NERVOUS SYSTEM SUPPORT*/PHARMACEUTICAL GRADE: Supports glycogen storage, thereby making more glucose available for energy production*
CLASSIFICATIONS/CERTIFICATIONS: Non-GMO, Soy Free, Vegan
GMP Quality Assured: NPA A-rated GMP certification means that every aspect of the NOW manufacturing process has been examined, including our laboratory/testing methods (for stability, potency, and product formulation)
Packaged in the USA by a family owned and operated company since 1968
NOW’s pharmaceutical-grade glycine powder delivers the clinically studied 3-gram dose in a single serving, making it the most practical and cost-effective way to use glycine for sleep.
Each 3/4 level teaspoon provides 3,000mg of free-form glycine with zero other ingredients. The formula is pharmaceutical grade, non-GMO, soy-free, vegan, and manufactured in a GMP-certified facility that has earned an NPA A-rating. NOW is a family-owned company operating since 1968, and this 1-pound container provides approximately 151 servings. Glycine has a naturally sweet taste, so it mixes easily into water without any flavoring needed.
Pros:
Delivers the full 3g clinical dose in a single serving
Pharmaceutical grade with zero fillers or additives
151 servings per container at an exceptional price per serving
Cons:
Requires measuring with a teaspoon (less convenient than capsules)
Powder form may not be ideal for travel
Best for: Anyone who wants the clinically studied glycine dose at the lowest cost per serving
2. Life Extension Glycine – Best Capsule
Life Extension Glycine, 1000 mg, Amino Acid That Promotes Healthy Sleep, Gluten-Free, Non-GMO, Vegetarian, 100 Capsules
Calming sleep support – Glycine is considered a semi-essential amino acid that has a calming effect on the brain. Because of this, glycine promotes relaxation and your ability to fall asleep.
Stay clear-headed – Glycine can help promote healthy, quality sleep without leaving you cloudy-headed the next day. Glycine also supports memory performance in related studies.
Healthy dose – We formulated our gluten-free, vegetarian Glycine with 1000 mg, a significantly higher dose than many traditional glycine supplements, to provide the maximum benefits.
Ingredients matter – We use the finest raw ingredients chosen for quality and purity. The majority of our products are non-GMO, gluten-free and manufactured in the USA with globally sourced ingredients, and a Certificate of Analysis is available for each.
Live your healthiest life – We believe the answers to a healthier life are within reach, and that scientific research is the key to getting us there. That’s why so many of our formulas feature specific ingredients and amounts based on scientific studies.
Life Extension delivers 1,000mg of glycine per capsule in a clean, vegetarian formula backed by one of the most trusted names in longevity-focused supplementation.
Each capsule provides 1,000mg of glycine, a significantly higher dose than many competing capsule products. Three capsules deliver the full 3g dose used in clinical sleep studies. Life Extension sources only the finest raw materials and provides a Certificate of Analysis for every product. The formula is gluten-free, non-GMO, and vegetarian. Clinical trials suggest glycine may help support healthy glucose metabolism, preserve muscle mass, and promote healthy body composition in addition to sleep benefits.
Pros:
1,000mg per capsule allows flexible dosing
Backed by Life Extension’s rigorous quality standards and clinical research focus
Certificate of Analysis available for every batch
Cons:
Need three capsules to reach the 3g clinical dose
Only 100 capsules per bottle (about 33 servings at 3 capsules)
Best for: People who prefer capsules and want a trusted, research-focused supplement brand
3. Double Wood Glycine – Best Value Capsule
Glycine Supplement – 1,000mg Glycine Powder per Serving (300 Capsules) The Relaxing Amino Acid (Glicina) (Third Party Tested, Gluten Free, Non-GMO) by Double Wood
IMPROVES SLEEP QUALITY: Glycine, a semi-essential amino acid, may support relaxation and the ability to fall asleep due to its potential calming effect on the brain
IMPROVES COGNITIVE CLARITY: Studies suggest glycine may support memory performance.
INGREDIENT PURITY: Our gluten-free, Glycine contains 1000 mg per serving, a higher dose than many other brands supplements, maximizing potential benefits
ROOTED IN QUALITY: Manufactured and Tested in the USA from Globally Sourced Ingredients. Double Wood’s Glycine is manufactured and tested for microbes and heavy metals right here in the USA from Globally Sourced Ingredients. Plus, it is Non-GMO and gluten-free
WE BOTTLE WELLNESS: At Double Wood we provide pure, potent supplements that deliver exceptional value, all backed by careful sourcing and rigorous third-party testing
Double Wood packs 300 capsules of 1,000mg glycine into a single bottle at an affordable price, making it the best value for capsule-format glycine.
Each capsule delivers 1,000mg of free-form glycine, and the 300-capsule bottle provides 100 servings at the 3-capsule clinical dose. Double Wood manufactures and tests all products in the USA from globally sourced ingredients, with third-party testing for microbes and heavy metals. The formula is non-GMO and gluten-free. The brand is known for offering pure, single-ingredient supplements without unnecessary additives at competitive prices.
Pros:
300 capsules per bottle for outstanding long-term value
Third-party tested for heavy metals and microbes in the USA
Clean, single-ingredient formula with no fillers
Cons:
Less established brand than Life Extension or Thorne
Still requires three capsules for the full clinical dose
Best for: Value-focused buyers who want a large supply of glycine capsules without compromising on quality
4. Thorne Glycine – Best Practitioner-Grade
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Thorne is one of the most respected names in practitioner-grade supplements, and their glycine delivers clean, NSF-certified quality with every capsule.
Each capsule provides 1,000mg of glycine in Thorne’s signature clean formula. Thorne is NSF Certified for Sport and widely recommended by healthcare practitioners, functional medicine doctors, and professional athletes. The company controls its entire manufacturing process and tests every batch for potency and purity. The 250-capsule bottle provides approximately 83 servings at the 3-capsule clinical dose. The formula contains no gluten, eggs, tree nuts, peanuts, or artificial colors or flavors.
Pros:
NSF Certified for Sport with practitioner-grade quality standards
250 capsules per bottle for a generous supply
Trusted by healthcare professionals and athletes worldwide
Cons:
Premium price reflects practitioner-grade positioning
Capsules are larger than some competing products
Best for: Athletes, health professionals, and anyone who wants the highest manufacturing standards
5. Micro Ingredients Glycine – Best Double-Strength
Micro Ingredients Glycine 2,000mg Per Serving, 240 Veggie Capsules | Free Form | Double Strength Amino Acids | Restful Sleep and Neurotransmitter Support Supplements | Non-GMO, Gluten Free
Micro Ingredients offers double strength Glycine veggie capsules, delivering 2,000mg of free-form Glycine per serving. Designed for soothing benefits and easy absorption.
Each bottle contains 240 natural veggie capsules, offering 2,000mg of essential glycine amino acid support per serving.
Glycine supports neurotransmitter function for restful sleep without drowsiness. Wake up feeling refreshed and ready to take on the day with natural sleep support.
A multi-functional amino acid that also plays a key role in collagen protein production, promoting healthy hair, skin, nails, and joints for men and women.
Premium non-GMO supplements. Made without wheat, soy, dairy, gluten, peanuts, and tree nuts. Ingredients must pass our 3rd party lab tests to ensure a product that is safe, pure, and potent.
Micro Ingredients delivers 2,000mg of free-form glycine per serving in veggie capsules, cutting the number of capsules needed to reach the clinical dose nearly in half.
Each two-capsule serving provides 2,000mg of glycine, meaning just three capsules get you to the 3g clinical dose versus six capsules with 500mg products. The formula uses free-form glycine for maximum absorption with no breakdown required. All ingredients pass third-party lab tests for safety, purity, and potency. The product is non-GMO and free from wheat, soy, dairy, gluten, peanuts, and tree nuts. Each bottle contains 240 veggie capsules for 120 servings at the two-capsule dose.
Pros:
Double-strength 2,000mg serving reduces capsule count
240 capsules per bottle for excellent value
Third-party tested and free from all major allergens
Cons:
Newer brand with less track record than established names
Still need additional capsule to reach full 3g clinical dose
Best for: People who want higher-dose capsules to minimize the number of pills taken daily
6. Pure Encapsulations Glycine – Best Premium
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Pure Encapsulations is the go-to brand for hypoallergenic, practitioner-grade supplements, and their glycine is no exception with its ultra-clean formula.
Each capsule delivers 500mg of glycine in Pure Encapsulations’ signature hypoallergenic capsule. The brand is widely recommended by healthcare practitioners and is known for its rigorous avoidance of unnecessary additives, coatings, and common allergens. The formula supports restful sleep and liver detoxification. Each bottle contains 180 capsules. Pure Encapsulations products are vegan, gluten-free, and manufactured under strict quality controls.
Pros:
Hypoallergenic formula ideal for sensitive individuals
Practitioner-recommended brand with exceptional quality reputation
Supports both sleep and liver detoxification
Cons:
Only 500mg per capsule means six capsules needed for the 3g dose
Premium pricing compared to standard glycine products
Best for: People with sensitivities or allergies who need a hypoallergenic glycine supplement
7. BulkSupplements.com Glycine Powder – Best Bulk Value
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BulkSupplements offers pure glycine powder in bulk quantities up to 1 kilogram, delivering the absolute lowest cost per serving for long-term glycine users.
Each 3g serving provides pure glycine powder with no fillers, additives, or flavoring. BulkSupplements is known for single-ingredient, lab-tested powders sold at wholesale pricing. The glycine powder is unflavored with a naturally sweet taste, making it easy to mix into water, juice, or smoothies. The 1kg bag provides over 300 servings at the 3g clinical dose. All products are manufactured in a GMP-certified, FDA-registered facility and third-party tested for purity.
Pros:
Lowest cost per serving of any glycine product on the market
Over 300 servings per 1kg bag
GMP-certified, FDA-registered facility with third-party testing
Cons:
Requires a scale or measuring spoon for accurate dosing
Minimal branding and packaging compared to premium brands
Best for: Long-term glycine users who want to buy in bulk at the lowest possible cost
8. NOW Foods Glycine 1000mg Capsules – Best Capsule from NOW
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For those who prefer capsules over powder, NOW Foods also offers glycine in a convenient 1,000mg vegan capsule backed by the same pharmaceutical-grade quality as their powder.
Each capsule provides 1,000mg of free-form, pharmaceutical-grade glycine. The formula is vegan, kosher, non-GMO, soy-free, and gluten-free. NOW Foods’ manufacturing facility holds an NPA A-rated GMP certification, ensuring every aspect of production meets the highest standards. Each bottle contains 200 capsules. The capsules are a great option for people who love NOW’s quality but prefer not to measure powder.
Pros:
Pharmaceutical-grade glycine from a trusted legacy brand
200 capsules per bottle for a long-lasting supply
Vegan, kosher, and certified GMP
Cons:
Capsules are larger due to the 1,000mg dose
Three capsules needed for the full 3g clinical dose
Best for: NOW Foods fans who want glycine capsules from a brand they already trust
How to Choose the Best Glycine Supplement for Sleep
The most important consideration when choosing a glycine supplement for sleep is the dose. Clinical studies showing sleep benefits used 3 grams (3,000mg) of glycine taken before bed. Powder forms make it easy to hit this dose in a single serving, while capsules typically require taking two to six pills depending on the per-capsule dose. If convenience matters, look for higher-dose capsules (1,000mg to 2,000mg) to minimize pill count.
Glycine is a simple amino acid, so there is no need for proprietary blends, patented forms, or added ingredients. The best glycine supplements contain pure, free-form glycine with minimal fillers. Since all glycine supplements contain the same molecular form of the amino acid, the primary differentiators are purity, third-party testing, price per serving, and capsule versus powder format.
For sleep use, take glycine 30 to 60 minutes before bed. Powder dissolves easily in water and has a naturally sweet taste, making it pleasant to drink without flavoring. Look for products that are third-party tested, GMP-certified, and free from common allergens. If you are using glycine long-term, powder formats from bulk suppliers offer the best value per serving by a significant margin.
Frequently Asked Questions
What is glycine and how does it improve sleep?
Glycine is a non-essential amino acid that functions as both a building block for proteins and an inhibitory neurotransmitter in the brain. When taken before bed, glycine lowers core body temperature by increasing blood flow to the extremities, which is a key signal for the body to initiate sleep. It also increases serotonin levels, which helps regulate sleep-wake cycles and supports deeper, more restorative sleep stages.
How much glycine should I take for sleep?
Clinical studies showing sleep benefits used 3 grams (3,000mg) of glycine taken about 30 to 60 minutes before bedtime. This dose was shown to improve subjective sleep quality, reduce the time to fall asleep, and decrease daytime sleepiness without causing any grogginess. Some people take up to 5 grams, but 3 grams is the most studied and recommended dose for sleep.
When is the best time to take glycine for sleep?
Take glycine 30 to 60 minutes before you plan to go to bed. This timing allows the amino acid to begin lowering core body temperature and increasing serotonin production as you prepare for sleep. Glycine can be mixed into water or taken as capsules on an empty stomach or with a light snack.
Are there any side effects of glycine supplements?
Glycine is generally very well tolerated. In clinical studies, the 3-gram sleep dose did not cause any significant side effects. Doses as high as 31 grams per day have been used in research without serious adverse effects. Some people may experience mild gastrointestinal discomfort at higher doses. Glycine does not cause next-day grogginess, which is one of its key advantages over synthetic sleep aids.
Can I take glycine with other sleep supplements?
Yes, glycine works well alongside other natural sleep supplements. It pairs particularly well with magnesium glycinate (which itself contains glycine), L-theanine, and tart cherry extract. Because glycine works through a different mechanism than melatonin (temperature regulation versus circadian signaling), the two can complement each other. Always start with one supplement at a time to gauge your individual response.
How long does it take for glycine to improve sleep?
Many people notice improved sleep quality on the very first night of taking glycine. The effects on body temperature and serotonin production are relatively fast-acting compared to supplements that require weeks of buildup. However, consistent nightly use over one to two weeks typically produces the most reliable and noticeable improvements in sleep quality, morning alertness, and daytime energy levels.