Effects of probiotic supplementation on sleep and psychological outcomes in adults with mild-to-moderate insomnia symptoms and work-related stress: A randomized, placebo-controlled, double-blind trial

This study aimed to investigate the effects of the Cerebiome® probiotic supplement on mild to moderate insomnia symptoms associated with work-related stress. Using a randomized, placebo-controlled, double-blind, parallel design, adults aged 18-65 with mild to moderate insomnia symptoms but no diagnosis of mental disorder or severe psychosocial distress, were randomized at a 1:1 ratio to receive probiotics or placebo daily for 12 weeks. The primary outcome was a reduction of the Insomnia Severity Index score at the end of the intervention. Secondary outcomes included changes in psychological symptoms, sleep quality, work activity, quality of life, and biological measures. Seventy participants (43 women; 43.9 ± 9.3 years) were randomly allocated to probiotics (n = 35) or placebo (n = 35). At week 12, both groups had a significant reduction in insomnia severity compared to baseline (probiotics: -5.2 [-6.8 to -3.6], p < 0.0001, d = 1.55; placebo: -5.5 [-7.1 to -3.9], p < 0.0001, d = 1.63), with no significant between-group difference (p = 0.82, d = 0.08). The probiotics group showed a significant improvement on the PHQ-9 (depressive symptoms) at week 12 (-1.5 [-2.4 to -0.5], p = 0.0043, d = 0.71), with a significant difference between groups (p = 0.05, d = 0.51). There was no difference in the number of adverse events and no severe adverse events. Twelve weeks of supplementation with Cerebiome® in participants with insomnia symptoms associated with work-related stress led to a significant improvement in mood but not in insomnia symptoms when compared to placebo. CLINICAL TRIAL REGISTRATION: ClinicalTrials.gov NCT04767997, registered on February 19th, 2021.