Associations between religiosity and sleep: A systematic review of observational studies in the adult population.

Sleep disturbances are common and linked to adverse physical and mental health. Religiosity, including beliefs, practices, and coping strategies, has been proposed as a factor influencing sleep quality, but findings across studies are heterogeneous. This systematic review examines the associations between religiosity and sleep quality and identifies potential psychological and behavioral mediators and moderators. The review was conducted following the guidelines of the Cochrane Handbook and reported in accordance with PRISMA guidelines. Study quality was appraised using the Joanna Briggs Institute (JBI) critical appraisal tools. The systematic search, conducted across multiple databases, yielded nine cross-sectional studies (2011-2024) with 14,221 adults aged 17-107 years. Higher religiosity, e.g., higher religious attendance and spiritual support, was generally associated with better sleep quality, whereas religious doubts and crises of faith were linked to poorer sleep outcomes. Mediators included sense of meaning and purpose, hope, health locus of control, and psychological distress. Future longitudinal and experimental studies should incorporate objective sleep measures such as actigraphy alongside self-reports, and employ more nuanced assessments of religiosity, including beliefs, religious orientations, and personal spiritual experiences, rather than focusing solely on affiliation or attendance. These approaches will help clarify causal pathways linking religiosity to sleep quality.