Can probiotics help you sleep better?

By Priyanjana Pramanik, MSc.Reviewed by Susha Cheriyedath, M.Sc.Jul 20 2025

Could the key to better sleep and brighter mood lie in your gut? New research suggests probiotic supplements may safely ease insomnia and depressive symptoms, but more studies are needed to pinpoint who benefits most.

Study: Impact of probiotics on sleep quality and mood states in patients with insomnia: a systematic review and meta-analysis. Image Credit: alphaspirit.it / Shutterstock

In a recent review article published in the journal Frontiers in Microbiology, researchers summarized the current scientific knowledge on the effects of probiotic supplementation on sleep quality and mood in individuals with insomnia.

Based on the evidence from randomized controlled trials (RCTs), they concluded that probiotic interventions may significantly improve sleep quality (with moderate certainty) and reduce symptoms of depression (with very low certainty) without increasing the risk of adverse events. However, these results were highly heterogeneous, and the overall strength of evidence varied between outcomes.

A high burden of insomnia

Insomnia is a widespread sleep disorder characterized by difficulty falling or staying asleep, or experiencing non-restorative sleep, that occurs frequently over at least three months. It can occur on its own (primary insomnia) or due to other conditions (secondary insomnia), though the two are often difficult to distinguish.

The disorder is linked to heightened brain activity and physiological imbalances, such as overactive stress responses and disruptions in neurotransmitter function, that hinder normal sleep.

Affecting 30–50% of adults at some point in their lifetimes, insomnia is associated with serious health risks, including increased suicide risk, cardiovascular disease, diabetes, fatigue, and poor concentration.

Although treatments like cognitive-behavioral therapy and sleep medications are available, they have drawbacks like high cost or potential dependency, highlighting the need for accessible and safer alternatives.

Emerging research suggests that gut microbiota may influence sleep quality, and probiotics could help by restoring gut balance and regulating sleep-related neurotransmitters.

About the review

This meta-analysis was designed to evaluate the effectiveness of probiotics in improving sleep and mood among individuals with insomnia. Researchers conducted a systematic search of eight databases to identify RCTs that assessed probiotic interventions for insomnia treatment, including six studies in the review and meta-analysis.

The included RCTs were published between 2018 and 2024, involving 424 patients with insomnia across China, Japan, South Korea, and Australia. Approximately 29.5% of the participants were male, with an average age of 39.3 years. Of these, 223 received probiotics, while 201 were in control groups. The probiotic strains used included Lactobacillus sakei B2-16, Saccharomyces boulardii, Bifidobacterium adolescentis SBT2786, Lactobacillus acidophilus DDS-1, multi-strain formulations, and Bifidobacterium active bacteria capsules. The Cochrane Risk of Bias tool revealed that four studies had a low risk of bias, while two showed high risk, mainly due to unclear randomization and allocation procedures.

Impacts on sleep and mood

All six studies reported changes in the Pittsburgh Sleep Quality Index (PSQI). Probiotic supplementation resulted in a significant reduction in PSQI scores, indicating a clinically meaningful improvement in sleep quality. The certainty of this evidence was rated as moderate. However, substantial heterogeneity was observed, suggesting variability across studies.

Subgroup analyses found that positive effects on sleep quality were observed primarily in participants from China and Australia, while no significant improvements were noted in studies from Japan or South Korea.

Total time spent sleeping was explored in three studies involving 226 patients. No significant improvement was found in the probiotic group, with high variability across studies. The certainty of evidence for this outcome was rated very low.

Sleep efficiency, defined as the percentage of time that is spent asleep while in bed, was included as an outcome in two studies involving 166 patients, with no significant changes observed. The certainty of evidence for sleep efficiency was rated as moderate.

Sleep latency, defined as the time it takes for individuals to transition from being fully awake to falling asleep, was included as an outcome in three studies involving 226 patients. A modest but borderline significant reduction in the time to fall asleep was observed. This result had moderate certainty but limited clinical significance.

Two studies involving 140 patients included depressive symptoms as an outcome. A clinically and statistically significant reduction in depression scores was observed in the intervention group that received probiotic supplementation, suggesting potential mental health benefits. However, the certainty of this evidence was rated as very low, and publication bias could not be ruled out.

While adverse events were reported in two studies, no significant differences in total adverse events were observed between the control and probiotic groups, indicating that probiotics show a high level of tolerability. The rate of adverse events was numerically higher in the probiotic group, but the difference was not statistically significant. Most adverse events were mild and self-limiting.

Conclusions

This meta-analysis is the first to systematically evaluate the effect of probiotics on insomnia. The findings show that probiotic supplements can significantly improve sleep quality (moderate certainty) and reduce symptoms of depression in people with insomnia, but with very low certainty and possible publication bias for depression outcomes and no clear impact on total sleep time, sleep efficiency, or sleep latency (with low to very low certainty).

Biologically, probiotics may help regulate sleep and mood through the gut-brain axis, influencing neurotransmitters (like GABA and serotonin), sleep-related hormones (like melatonin), and reducing inflammation. These mechanisms could explain their benefits on both sleep and mental health.

Importantly, probiotics were found to be safe and well-tolerated, with only mild, temporary side effects reported.

Despite promising results, the review has several limitations. The number of included studies was small, and most had variations in probiotic strains, doses, and treatment lengths. Some studies lacked blinding or proper randomization, and few included older adults, which limited their applicability to this population.

In conclusion, probiotics appear to be a safe and natural option for supporting sleep and mood in individuals with insomnia. However, the strength of evidence is variable, and larger, high-quality studies are needed to confirm these results and identify the best probiotic types and treatment strategies.