You may have heard that your gut and brain are connected, and that probiotics might affect how you feel and sleep. Researchers are actively studying this idea. Here we look at what L. rhamnosus is, why the strain matters, and what gut–brain research has found so far.
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.
- L. rhamnosus is a common probiotic bacterium. It is one of three probiotics in Sleep Harmony. [1][6]
- The strain matters. The effects of one strain do not necessarily apply to another strain of the same species. [1][2]
- A mouse study found effects on stress-related behavior. These effects depended on the vagus nerve, a main link between the gut and the brain. [3][4]
- The same strain did not show these effects in healthy men. It did not change mood, stress or sleep quality compared with placebo. [5]
Facts at a Glance
| Fact | Detail |
|---|---|
| Ingredient | L. rhamnosus (Lacticaseibacillus rhamnosus), one of 3 probiotics in Sleep Harmony [1][6] |
| Amount in Sleep Harmony | 2 billion CFU a day, in 2 capsules [6] |
| Strain studied (mice) | JB-1 — less stress-related behavior, vagus-nerve dependent [3] |
| Strain studied (humans) | JB-1 — no change in mood, stress or sleep quality vs. placebo [5] |
| Last reviewed | [DATE] |
What Is L. Rhamnosus?
Probiotics are live microorganisms intended to have health benefits when consumed. [2]
L. rhamnosus is one of these bacteria. The NIH Office of Dietary Supplements uses its newer name, Lacticaseibacillus rhamnosus, so you may see either name. [1] Sleep Harmony contains 2 billion colony-forming units (CFUs) of L. rhamnosus in each two-capsule serving. [6] CFUs show how many live microorganisms a product contains. [1]
Why the Strain Matters
Probiotics are named by their genus, species and strain. [1] For example, in Lacticaseibacillus rhamnosus GG, Lacticaseibacillus is the genus, rhamnosus is the species and GG is the strain. [1]
This matters because different strains can have different effects. NCCIH explains that if one kind of Lactobacillus helps, another kind may not. [2]
Like most probiotic supplement labels, Sleep Harmony's lists the species and the CFU count, not the specific strain — that's standard across the probiotic industry, since strain-level identification and testing add cost that most brands don't carry. So we can't confirm that Sleep Harmony's L. rhamnosus is the exact JB-1 strain used in the studies below; treat the research in this article as what's known about L. rhamnosus as a species, not a guarantee about this specific product.
The Gut–Brain Connection, in Plain Language
Cleveland Clinic describes the gut–brain connection as a two-way link. Signals pass both ways between your digestive system and your brain. [4] The vagus nerve is the main link between the nerves of the gut and the brain. [4]
Gut microbes help make many of the chemical messengers that carry signals between the gut and the brain. [4] This is an active area of research, and much is still unknown.
What Does the Research Show?
A study in mice
A 2011 study gave mice a specific strain of L. rhamnosus, called JB-1. [3] The mice showed less stress-related behavior and lower levels of a stress hormone. [3] Their brains also showed changes in receptors for GABA, a calming messenger. [3]
When the vagus nerve was cut, these effects did not appear. [3] This pointed to the vagus nerve as a main path between gut bacteria and the brain. [3]
The same strain in healthy men
A later study tested the same strain, JB-1, in 29 healthy men. [5] Each man took the probiotic for 8 weeks and a placebo for 8 weeks, in random order. [5]
The probiotic did not change mood, anxiety, stress or sleep quality compared with placebo. [5] The researchers described this as a result that was "lost in translation" from mice to people. [5]
A result in animals does not always carry over to people.
Study summary
| Study | Who | Strain | Length | Main Result |
|---|---|---|---|---|
| Bravo et al., 2011 [3] | Mice | JB-1 | — | Less stress-related behavior; depended on the vagus nerve. |
| Kelly et al., 2017 [5] | 29 healthy men | JB-1 | 8 weeks each | No effect on mood, stress or sleep quality vs. placebo. |
How Much Is in Sleep Harmony?
Sleep Harmony contains 2 billion CFU of L. rhamnosus per 2-capsule serving. [6] The studies above used a specific named strain, JB-1, rather than reporting a CFU amount comparable to a label. [3][5]
| Source | L. rhamnosus | Notes |
|---|---|---|
| Sleep Harmony (2 capsules) | 2 billion CFU | Strain not specified on the label [6] |
| Studies above | Strain JB-1 | Amounts not comparable — strains and measurement differ [3][5] |
14 ingredients, including 2 billion CFU of L. rhamnosus
Sleep Harmony is a nightly two-capsule supplement that pairs L. rhamnosus 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 is greater in people with severe illnesses or weakened immune systems. [2] Some probiotic products have been found to contain microorganisms other than those on the label. [2]
L. Rhamnosus 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. rhamnosus 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 one strain of L. rhamnosus by itself.
If you take Sleep Harmony, you are not relying on L. rhamnosus alone. It is one of 14 ingredients in each serving.
- In healthy people, probiotics may cause gas, but they rarely cause infections or other health problems. [1]
- People with a serious illness or a weakened immune system face a greater risk. [2]
- If either applies to you, or you are pregnant or taking medicines, please check with your doctor or pharmacist before use.
If You Are Deciding
The evidence for L. rhamnosus and sleep is early. Cleveland Clinic suggests a steady sleep schedule, less caffeine and alcohol, and a cool, dark bedroom. [7]
If you would like to try Sleep Harmony, the directions are two capsules 30 to 60 minutes before bedtime. [6]
The Short Version
L. rhamnosus is a common probiotic, and its effects depend on the strain. In mice, one strain reduced stress-related behavior through the vagus nerve. In healthy men, the same strain did not change mood, stress or sleep quality. Sleep Harmony contains 2 billion CFU, alongside 13 other ingredients.
Frequently Asked Questions
Do probiotics help you sleep?
What is the gut–brain connection?
Why does the probiotic strain matter?
Who should be careful with probiotics?
What are the side effects of probiotics?
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
- Bravo JA, Forsythe P, Chew MV, et al. Ingestion of Lactobacillus strain regulates emotional behavior and central GABA receptor expression in a mouse via the vagus nerve. Proc Natl Acad Sci USA. 2011;108(38):16050–16055. doi:10.1073/pnas.1102999108. PMID: 21876150.
- Cleveland Clinic. The gut-brain connection. Last updated September 20, 2023. https://my.clevelandclinic.org/health/body/the-gut-brain-connection
- Kelly JR, Allen AP, Temko A, et al. Lost in translation? The potential psychobiotic Lactobacillus rhamnosus (JB-1) fails to modulate stress or cognitive performance in healthy male subjects. Brain Behav Immun. 2017;61:50–59. doi:10.1016/j.bbi.2016.11.018. PMID: 27865949.
- Anirva. Sleep Harmony with Probiotics: Supplement Facts label and product page. https://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. https://health.clevelandclinic.org/does-magnesium-help-you-sleep/
