The Effect of Probiotic Supplementation on Self-Reported Sleep Quality

Abstract

Objectives: A growing body of evidence suggests that the microbiome plays an important role in mental health. Few studies have examined how probiotic supplementation affects sleep quality. The current study investigated the impact of probiotics on self-reported sleep quality and the role of anxiety in moderating this relationship. The study also assessed the role of vagal tone in mediating probiotic-induced improvements in self-reported sleep quality. Methods: Forty-three undergraduates at the University of Kansas participated in a two-week study assessing the effect of probiotic supplementation on psychological and physiological processes. A sleep diary was collected daily. Measures of sleep, anxiety, and vagal tone were collected at baseline and post-intervention. Indices of sleep quality were analyzed using multilevel growth modeling. The moderating effects of treatment condition and initial anxiety were examined. The meditating effect of vagal tone was also assessed. Results: Initial level of anxiety was found to moderate the effect of probiotic supplementation on sleep onset latency (SOL) and sleep efficiency. In participants without elevated anxiety, probiotic supplementation was associated with a significant decrease in SOL and a significant increase in sleep efficiency over the course of the two-week trial. The effectiveness of probiotic supplementation increased as anxiety decreased. Probiotic supplementation had no effect on SOL and sleep efficiency in participants with elevated levels of anxiety. No association was found between treatment condition and number of awakenings or minutes awake after sleep onset. Finally, change in vagal tone was not found to mediate change in sleep quality. Conclusion: These findings suggest that the microbiome influences sleep quality. Manipulation of the microbiome via probiotic supplementation may be useful for treating individuals with disrupted sleep.