Meta-analysis finds limited and inconsistent evidence for probiotics improving sleep

What's new

A meta-analysis of 39 randomized controlled trials explored the effects of probiotic supplementation on both subjective and objective measures of sleep [1]. The findings suggest that while probiotics might offer some minor benefits, the evidence is generally weak and inconsistent. The study observed small improvements in subjective sleep quality and, to a lesser extent, in objective measures like total sleep time and the duration of wakefulness after sleep onset. However, these effects were often based on a limited number of studies, and the wide variety of probiotic strains and formulations used made it difficult to draw firm conclusions.

The science behind it

The meta-analysis synthesized data from trials involving men and women, primarily aged 20–70, most of whom did not have pre-existing health conditions or diagnosed sleep disorders [1]. Participants typically took various single-strain or multi-strain probiotic supplements daily for periods ranging from 4 to 12 weeks. When compared to a placebo, probiotics showed a slight improvement in subjective sleep quality, as reported by participants across 10 studies. For objective sleep parameters, the analysis indicated an average increase of 14 minutes in total sleep time across 3 studies and a reduction of 5 minutes in the time spent awake after initially falling asleep, observed in 2 studies. The variability in results across studies is likely due to the diverse range of probiotic interventions, as the efficacy of probiotics can be highly strain-specific [2]. This highlights a key challenge in probiotic research: different strains can have different effects, making it difficult to generalize findings across various products.

Probiotics are believed to exert their effects by modulating the gut microbiota, which in turn can influence various physiological processes, including those related to sleep [1]. The gut-brain axis, a bidirectional communication system between the gut and the central nervous system, is a potential pathway through which probiotics could impact sleep. Changes in gut microbiota composition can affect neurotransmitter production, inflammation, and stress responses, all of which are factors that can influence sleep patterns. However, the exact mechanisms by which specific probiotic strains might influence sleep remain largely unclear and require further investigation.

What it means in practice

For individuals considering probiotics to improve sleep, this meta-analysis suggests that the benefits are likely to be modest at best and not universally observed. Given the small effect sizes and the inconsistency across studies, probiotics should not be viewed as a primary solution for sleep issues. While some individuals might experience minor improvements, the current evidence does not support broad recommendations for probiotic use specifically for sleep enhancement. It's also important to recognize that the effects are highly dependent on the specific probiotic strain, and what works for one person or in one study may not work for another.

Those struggling with sleep problems should prioritize established interventions such as optimizing sleep hygiene, addressing underlying medical conditions, and consulting with healthcare professionals for personalized advice. If considering a probiotic, it would be prudent to discuss it with a doctor, especially given the lack of strong, consistent evidence for sleep benefits and the potential for strain-specific effects. The research indicates that more targeted and well-designed studies are needed to identify if particular probiotic strains or combinations could offer more significant and reliable sleep improvements.

Caveats

The primary limitation of this meta-analysis is the overall low quality and heterogeneity of the included studies [1]. Many of the observed benefits were based on a small number of trials, and the interventions varied significantly in terms of probiotic strains, dosages, and duration of supplementation. This variability makes it challenging to pinpoint which specific probiotics, if any, might be effective for sleep. Furthermore, most participants in the included studies did not have diagnosed sleep disorders, meaning the findings may not be directly applicable to individuals with clinical insomnia or other significant sleep disturbances. The reliance on subjective sleep quality measures in many studies also introduces potential bias, as self-reported improvements may not always align with objective physiological changes. Future research needs to employ standardized methodologies, larger sample sizes, and focus on specific probiotic strains to provide clearer insights into their potential role in sleep health.

Source: [1]