Can Probiotics Help You Sleep Better?

Could the key to better sleep and a brighter mood be hidden in your gut? A new study suggests that probiotic supplements may safely ease insomnia and depressive symptoms, but more research is needed to determine who benefits the most.

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

Based on data from randomised controlled trials (RCTs), they concluded that probiotic interventions can significantly improve sleep quality (moderate evidence) and reduce depressive symptoms (very low evidence) without increasing the risk of adverse effects. However, these results were highly heterogeneous, and the overall strength of evidence varied by measure.

High load from insomnia

The gut-brain axis matters: Probiotics likely improve sleep in part by reducing inflammation and balancing stress hormones (like cortisol) through the gut-brain communication network, not just through neurotransmitters.

Insomnia is a common sleep disorder characterized by difficulty falling or staying asleep, or a feeling of non-restorative sleep, that occurs frequently over a period of at least three months. It can be primary (occurring on its own) or secondary (associated with other conditions), although the two types are often difficult to distinguish.

The disorder is associated with increased brain activity and physiological disturbances, such as an overactive stress response and neurotransmitter imbalances that interfere with normal sleep.

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

While treatments such as cognitive behavioral therapy and sleep medications are available, they have drawbacks such as high cost and potential for addiction, highlighting the need for affordable and safer alternatives.

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

Description of the review

Not just GABA and serotonin: Research suggests that certain strains, such as Bifidobacterium breve CCFM1025, may act by influencing other compounds (such as serum daidzein) that regulate the body's stress response system.

This meta-analysis was designed to evaluate the effectiveness of probiotics in improving sleep and mood in people with insomnia. The researchers systematically searched eight databases to identify RCTs evaluating probiotic interventions for the treatment of insomnia. Six studies were included in the review and meta-analysis.

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

Effect on sleep and mood

All six studies reported changes in the Pittsburgh Sleep Quality Index (PSQI). Probiotic supplementation resulted in significant reductions in PSQI scores, indicating a clinically meaningful improvement in sleep quality. The certainty of these findings was rated as moderate. However, there was significant heterogeneity, suggesting variability in results between studies.

Subgroup analyses showed that positive effects on sleep quality were seen mainly in participants from China and Australia, while no significant improvements were observed in studies from Japan and South Korea.

Total sleep time was assessed in three studies involving 226 patients. No significant improvement was found in the probiotic group, with high variability between studies. The certainty of the evidence for this outcome was rated as very low.

Sleep efficiency, defined as the percentage of time in bed spent asleep, was included as an outcome in two studies involving 166 patients and no significant change was observed. The certainty of evidence for this outcome was rated as moderate.

Sleep onset time, defined as the period from full wakefulness to sleep onset, was included as an outcome in three studies involving 226 patients. A modest but borderline significant reduction in sleep onset time was observed. This finding was of moderate significance but limited clinical relevance.

Two studies involving 140 patients included depressive symptoms as an outcome. There was a clinically and statistically significant reduction in depression scores in the probiotic group, suggesting potential mental health benefits. However, the certainty of these findings was rated as very low, and publication bias cannot be ruled out.

Although adverse events were reported in two studies, no significant differences in the overall incidence of adverse events were observed between the control and probiotic groups, indicating that probiotics are highly tolerable.

Conclusion

Although probiotics helped people experience improved sleep quality, they did not actually increase the percentage of time spent sleeping in bed (sleep efficiency) or the total number of hours of sleep in studies measuring these metrics.

This meta-analysis is the first to systematically evaluate the effects of probiotics on insomnia. The results suggest that probiotic supplementation may significantly improve sleep quality (moderate certainty) and reduce depressive symptoms in people with insomnia (very low certainty and possible publication bias). However, no clear effects were observed on total sleep time, sleep efficiency, or time to sleep onset (low to very low certainty).

From a biological perspective, probiotics may help regulate sleep and mood via the gut-brain axis by influencing neurotransmitters (e.g., GABA and serotonin), sleep hormones (e.g., melatonin), and reducing inflammation. These mechanisms may explain their benefits for sleep and mental health.

It is important to note that probiotics have been found to be safe and well tolerated, with only mild and short-term side effects.

Despite the encouraging results, the review has several limitations. The number of included studies was small, and most varied in the probiotic strains used, doses, and duration of treatment. Some studies were not blinded or randomized properly, and rarely included older adults, limiting their applicability to this population.

In conclusion, probiotics appear to be a safe and natural option for supporting sleep and mood in people with insomnia. However, the strength of the evidence varies, and larger, high-quality studies are needed to confirm these findings and determine the best types of probiotics and treatment strategies.