The effects of physical activity on cortisol and sleep: A systematic review and meta-analysis

Managing stress and having good quality sleep are inter-related factors that are essential for health, and both factors seem to be affected by physical activity. Although there is an established bidirectional relationship between stress and sleep, remarkably few studies have been designed to examine the effects of physical activity on cortisol, a key biomarker for stress, and sleep. Research is particularly scarce in older people despite both sleep and cortisol changing with age. This systematic literature review addresses this gap.

A systematic review was conducted following the PRISMA guidelines. Original, peer-reviewed records of intervention studies such as randomized controlled trials (RCTs) and non-RCTs with relevant control groups were eligible for inclusion. The Participant, Intervention, Comparison, Outcome (PICO) characteristics were (1) adults or older adults (2) physical activity programmes of any duration, (3) controls receiving no intervention or controls included in a different programme, (4) cortisol measurement, and subjective or objective measures of sleep.