You may have read that some probiotics can make GABA, a calming messenger in the brain. L. brevis is one of the bacteria most often mentioned. Here we look at what L. brevis is, what "GABA-producing" means, what the early sleep research found, and how much is in Sleep Harmony.
In this article
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.
- Some L. brevis strains make GABA in the lab. Researchers have chosen certain strains for study for this reason. [5]
- A small pilot study tested one strain for sleep. It used heat-killed bacteria and found mixed results. [3]
- Mice given the same strain had more deep sleep under stress. [4]
- Sleep Harmony contains 2 billion CFU of live L. brevis. The studies above used a heat-killed form of a different, named strain, so they may not apply directly. [6]
Facts at a Glance
| Fact | Detail |
|---|---|
| Ingredient | L. brevis (Levilactobacillus brevis), one of 3 probiotics in Sleep Harmony [5][6] |
| Amount in Sleep Harmony | 2 billion CFU a day (live), in 2 capsules [6] |
| Sleep pilot study | Heat-killed SBC8803, 17 men, 10 days [3] |
| Mouse study | Heat-killed SBC8803, more deep sleep under stress [4] |
| Last reviewed | [DATE] |
What Is L. Brevis?
L. brevis is a lactic acid bacterium sold as a probiotic. Researchers now also call it Levilactobacillus brevis. [5] Probiotics are live microorganisms intended to have health benefits when consumed. [2]
Sleep Harmony contains 2 billion colony-forming units (CFUs) of L. brevis in each two-capsule serving. [6] As we explain in our L. rhamnosus article, effects depend on the specific strain. [1][2] Like most probiotic labels, Sleep Harmony's names the species and CFU count rather than the strain, so we can't confirm whether it matches the strains studied below.
What "GABA-Producing" Means
GABA is a messenger that calms activity in the brain. [7] In a 2024 study, researchers chose an L. brevis strain partly because it made GABA in earlier lab tests. [5]
Making GABA in a lab dish is not the same as raising GABA in the brain. As we explain in our GABA article, it is not known whether GABA from the gut reaches the brain in people. In the 2024 study, GABA levels measured in stool did not track with the mood or thinking results. [5]
What Does the Research Show?
A small sleep pilot study in men
This 2016 pilot study included 17 men aged 41 to 69 with mild sleep complaints. [3] They took 25 mg a day of a heat-killed L. brevis strain called SBC8803, or a placebo, for 10 days each. [3] The study was not randomized, and 14 men were included in the final analysis. [3]
Brain-wave sleep measures did not differ between the probiotic and placebo overall. [3] In sleep diaries, men reported better results for waking during the night. [3] The researchers worked for the company that makes this strain. [3]
A study in stressed mice
A 2019 study fed mice the same heat-killed strain for six weeks, with stress added in the last two weeks. [4] The mice had more deep (non-REM) sleep and steadier activity rhythms than mice on a standard diet. [4] These are results in mice.
A mood and thinking study in adults
The 2024 study gave 44 adults with moderate stress a two-strain product with L. brevis P30021 and a second probiotic. [5] Over a 12-week crossover, it had no effect on self-rated stress. [5] Some mood-related thinking measures changed, and sleep was not measured. [5]
Study summary
| Study | Who | Product | Length | Main Result |
|---|---|---|---|---|
| Nakakita et al., 2016 [3] | 17 men, 41–69 | Heat-killed SBC8803, 25 mg | 10 days each | No overall brain-wave difference; better diary scores for night waking. |
| Higo-Yamamoto et al., 2019 [4] | Stressed mice | Heat-killed SBC8803 in food | 6 weeks | More deep sleep than standard diet. |
| Casertano et al., 2024 [5] | 44 adults with stress | L. brevis P30021 + L. plantarum P30025 | 12 weeks (crossover) | No effect on self-rated stress; sleep not measured. |
Live vs. Heat-Killed Bacteria
The two sleep studies used heat-killed bacteria. [3][4] Sleep Harmony contains live bacteria, measured in CFUs. [6] Because heat-killed and live bacteria differ, and the strains may differ, the sleep results may not apply to Sleep Harmony.
How Much Is in Sleep Harmony?
Sleep Harmony contains 2 billion CFU of live L. brevis per 2-capsule serving. [6] The sleep pilot study used 25 mg of a heat-killed strain, measured by weight rather than CFU, so the two amounts aren't directly comparable.
| Source | L. brevis | Notes |
|---|---|---|
| Sleep Harmony (2 capsules) | 2 billion CFU (live) | Strain not specified on the label [6] |
| Sleep pilot study | 25 mg heat-killed SBC8803 | Measured by weight, not CFU [3] |
14 ingredients, including 2 billion CFU of live L. brevis
Sleep Harmony is a nightly two-capsule supplement that pairs L. brevis with two other probiotic strains, melatonin, valerian, magnesium, L-theanine and more. Every ingredient is listed on the label.
See Sleep HarmonySafety
The risk of harm from probiotics is greater in people with severe illnesses or weakened immune systems. [2]
L. Brevis 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. L. brevis 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 heat-killed L. brevis or a two-strain product.
If you take Sleep Harmony, you are not relying on L. brevis alone. It is one of 14 ingredients in each serving.
If You Are Deciding
The evidence for L. brevis and sleep is early. Cleveland Clinic suggests a steady sleep schedule, less caffeine and alcohol, and a cool, dark bedroom. [8]
If you would like to try Sleep Harmony, the directions are two capsules 30 to 60 minutes before bedtime. [6]
The Short Version
Some L. brevis strains make GABA in the lab, but that does not show they raise GABA in the brain. A small pilot study of one heat-killed strain found mixed sleep results. Sleep Harmony contains 2 billion CFU of live L. brevis, alongside 13 other ingredients.
Frequently Asked Questions
Does L. brevis help you sleep?
Do probiotics make GABA?
What are psychobiotics?
References
- NIH Office of Dietary Supplements. Probiotics: fact sheet for consumers. Updated November 17, 2025. https://ods.od.nih.gov/factsheets/Probiotics-Consumer/
- National Center for Complementary and Integrative Health. Probiotics: what you need to know. Last updated August 2019. https://www.nccih.nih.gov/health/probiotics-what-you-need-to-know
- Nakakita Y, Tsuchimoto N, Takata Y, Nakamura T. Effect of dietary heat-killed Lactobacillus brevis SBC8803 (SBL88™) on sleep: a non-randomised, double blind, placebo-controlled, and crossover pilot study. Benef Microbes. 2016;7(4):501–510. doi:10.3920/BM2015.0118. PMID: 27013460.
- Higo-Yamamoto S, Yamamoto S, Miyazaki K, et al. Dietary heat-killed Lactobacillus brevis SBC8803 attenuates chronic sleep disorders induced by psychophysiological stress in mice. J Nutr Sci Vitaminol. 2019;65(2):164–170. doi:10.3177/jnsv.65.164. PMID: 31061285.
- Casertano M, Dekker M, Valentino V, De Filippis F, Fogliano V, Ercolini D. GABA-producing lactobacilli boost cognitive reactivity to negative mood without improving cognitive performance: a human double-blind placebo-controlled cross-over study. Brain Behav Immun. 2024;122:256–265. doi:10.1016/j.bbi.2024.08.029.
- Anirva. Sleep Harmony with Probiotics: Supplement Facts label and product page. https://anirva.com/products/sleep-harmony (accessed September 30, 2026).
- Cleveland Clinic. Gamma-aminobutyric acid (GABA): what it is, function and benefits. Reviewed April 25, 2022. https://my.clevelandclinic.org/health/articles/22857-gamma-aminobutyric-acid-gaba
- Umeda N (expert). Does magnesium help you sleep better? Cleveland Clinic Health Essentials. September 4, 2026. https://health.clevelandclinic.org/does-magnesium-help-you-sleep/
