From Anirva, the maker of Sleep Harmony. This article is general information, not medical advice. These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure or prevent any disease.
If you have read about sleep and calm, you have probably met the word GABA. It is the brain's main calming signal, and it is also sold as a supplement. That raises a fair question: if you swallow GABA, does any of it reach the brain? Here we look at what GABA does, what researchers know about that question, what the sleep studies found, and how much GABA is in Sleep Harmony.
In this article
Key Takeaways
- GABA is the brain's main calming signal. It slows down nerve signals in the brain.
- Whether swallowed GABA reaches the brain is not settled. No study has measured this directly in people.
- A few small sleep studies are encouraging. People fell asleep faster in some trials of 100 to 300 mg a day.
- Sleep Harmony contains 100 mg. This matches the lower end of the amounts studied for sleep.
- The research is early. A 2020 review found very limited evidence for sleep so far.
What Is GABA, and What Does It Do in the Body?
GABA stands for gamma-aminobutyric acid. Cleveland Clinic describes it as a chemical messenger in the brain that slows the brain down by blocking certain signals [1]. It is the most common calming messenger in the central nervous system [1].
Your body makes its own GABA. It is also found in some foods. Cleveland Clinic lists fermented foods such as kimchi, miso and tempeh, as well as green, black and oolong tea [1]. Brown rice, soy, adzuki beans, spinach, broccoli and sprouted grains also contain some [1].
Can GABA From a Supplement Reach the Brain?
This is the most common question about GABA supplements. The short answer is that researchers do not know yet.
The brain is protected by the blood-brain barrier, a layer that controls what passes from the blood into the brain. Cleveland Clinic notes that much of the GABA you swallow might not get into the brain because of this barrier [1].
Animal studies give mixed answers. A 2015 review found that some studies showed GABA could cross the barrier, while others could not show it [2]. In mice, researchers identified a transport system for GABA at the blood-brain barrier [7]. However, the review found no study in people that directly measured whether GABA crosses into the brain [2]. A 2020 review reached the same conclusion [3].
Another Possible Route: the Gut and the Vagus Nerve
Researchers are also studying an indirect route. The gut has its own nerves, and the vagus nerve carries signals between the gut and the brain [2]. The 2015 review describes this as a possible way GABA could have effects even if little of it reaches the brain [2].
Some gut bacteria can also make GABA [2]. Our guide to L. brevis looks at this in more detail.
What Does the Research Show?
The research on GABA supplements and sleep is still growing. A 2020 review looked at 14 placebo-controlled studies of GABA taken by mouth [3]. It found limited evidence for stress and very limited evidence for sleep [3]. The authors call for more studies [3].
Three small sleep studies stand out.
A 4-week trial in adults with sleep complaints
This trial included 40 adults with trouble sleeping [4]. Thirty took 300 mg of GABA a day, made from fermented rice germ, and ten took a placebo. Sleep was measured overnight in a sleep lab [4].
After four weeks, the time it took to fall asleep dropped from about 13 minutes to about 6 minutes in the GABA group. It did not change in the placebo group [4]. The stages of sleep did not change [4]. The company that supplied the GABA funded the study [4].
Two 1-week studies at 100 mg
Two studies tested 100 mg of GABA for one week, measuring sleep with brain-wave recordings [3][5][6]. In the 2015 study, the authors reported that people fell asleep about 5 minutes faster [5]. The 2020 review described this result as a trend rather than a clear effect [3]. In the 2016 study, people fell asleep faster, spent more time in non-REM sleep and felt better on waking [3][6].
Study summary
| Study | People | Amount a Day | Length | Main Result |
|---|---|---|---|---|
| Hepsomali et al., 2020 (review) | 14 placebo-controlled studies | 100–300 mg for sleep | 1–4 weeks (sleep) | Limited evidence for stress; very limited for sleep. |
| Byun et al., 2018 | 40 adults with sleep complaints | 300 mg | 4 weeks | Fell asleep faster in a sleep lab vs. placebo; sleep stages unchanged. |
| Yamatsu et al., 2015 | Adults (small study) | 100 mg | 1 week | Fell asleep about 5 minutes faster (a trend, per the 2020 review). |
| Yamatsu et al., 2016 | Adults (small study) | 100 mg | 1 week | Fell asleep faster; more non-REM sleep; felt better on waking. |
How Much GABA Is in Sleep Harmony Compared With the Studies?
| Source | GABA a Day | Notes |
|---|---|---|
| Sleep Harmony (2 capsules) | 100 mg | From the label [8] |
| 1-week studies | 100 mg | Same amount |
| 4-week sleep-lab trial | 300 mg | From fermented rice germ |
| Sleep amounts in the 2020 review | 100–300 mg | — |
What the Research Does Not Show Yet
No study has measured directly whether GABA taken by mouth reaches the human brain [2][3].
The sleep studies were small and short, lasting one to four weeks [3].
The 4-week trial was funded by the company that supplied the GABA [4]. More independent studies would help.
Safety and Interactions
In the 4-week trial, 4 of the 40 people had mild side effects, and none were serious [4]. The studies were short, so less is known about taking GABA for many months [3].
Cleveland Clinic notes that there is no strong scientific evidence for using GABA supplements to treat medical conditions [1]. If you take medicines, especially ones that make you sleepy, a doctor or pharmacist can check whether GABA is right for you.
GABA Is One Part of Sleep Harmony
Sleep Harmony combines melatonin, calming herbs and three probiotics in one formula. We chose ingredients that have each been studied for relaxation and sleep. GABA is one of them.
Sleep Harmony has not been clinically tested as a finished product. For this reason, we cannot say how its ingredients work together. The studies in this article tested GABA by itself, and their results describe GABA alone.
If you take Sleep Harmony, you are not relying on GABA alone. It is one of 14 ingredients in each serving.
Good to Know
If You Are Deciding
GABA supplements are an area where the research is still early. The sleep studies are encouraging but small, and the question of how GABA works is still open.
Good sleep habits remain the base. Cleveland Clinic suggests a steady sleep schedule, less caffeine and alcohol, and a cool, dark bedroom. It also suggests putting screens away before bed [9]. If you would like to try Sleep Harmony, the directions are two capsules 30 to 60 minutes before bedtime [8].
The Short Version
GABA is the brain's main calming signal, and it is also sold as a supplement. Whether swallowed GABA reaches the brain is not yet known. A few small studies of 100 to 300 mg a day found that people fell asleep faster, but the overall evidence is limited. Sleep Harmony contains 100 mg, alongside 13 other ingredients.
Frequently Asked Questions
Does GABA help you sleep?
Can GABA cross the blood-brain barrier?
How much GABA is used for sleep?
How long does GABA take to work?
What are the side effects of GABA?
Is GABA safe to take every day?
What is the difference between GABA and L-theanine?
Does GABA help with stress and sleep?
Which foods contain GABA?
References
- Cleveland Clinic. Gamma-aminobutyric acid (GABA): what it is, function and benefits. Reviewed April 25, 2022. my.clevelandclinic.org
- Boonstra E, de Kleijn R, Colzato LS, Alkemade A, Forstmann BU, Nieuwenhuis S. Neurotransmitters as food supplements: the effects of GABA on brain and behavior. Front Psychol. 2015;6:1520. doi:10.3389/fpsyg.2015.01520. PMID: 26500584.
- Hepsomali P, Groeger JA, Nishihira J, Scholey A. Effects of oral gamma-aminobutyric acid (GABA) administration on stress and sleep in humans: a systematic review. Front Neurosci. 2020;14:923. doi:10.3389/fnins.2020.00923. PMID: 33041752.
- Byun JI, Shin YY, Chung SE, Shin WC. Safety and efficacy of gamma-aminobutyric acid from fermented rice germ in patients with insomnia symptoms: a randomized, double-blind trial. J Clin Neurol. 2018;14(3):291–295. doi:10.3988/jcn.2018.14.3.291. PMID: 29856155.
- Yamatsu A, Yamashita Y, Maru I, Yang J, Tatsuzaki J, Kim M. The improvement of sleep by oral intake of GABA and Apocynum venetum leaf extract. J Nutr Sci Vitaminol. 2015;61(2):182–187. doi:10.3177/jnsv.61.182. PMID: 26052150.
- Yamatsu A, Yamashita Y, Pandharipande T, Maru I, Kim M. Effect of oral γ-aminobutyric acid (GABA) administration on sleep and its absorption in humans. Food Sci Biotechnol. 2016;25(2):547–551. doi:10.1007/s10068-016-0076-9.
- Takanaga H, Ohtsuki S, Hosoya K, Terasaki T. GAT2/BGT-1 as a system responsible for the transport of γ-aminobutyric acid at the mouse blood-brain barrier. J Cereb Blood Flow Metab. 2001;21(10):1232–1239.
- Anirva. Sleep Harmony with Probiotics: Supplement Facts label and product page. anirva.com/products/sleep-harmony (accessed September 30, 2026).
- Umeda N (expert). Does magnesium help you sleep better? Cleveland Clinic Health Essentials. September 4, 2026. health.clevelandclinic.org
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