Does exercise improve sleep for adults with insomnia? A systematic review with quality appraisal

Insomnia is recognised as the most prevalent sleep disorder. Untreated insomnia carries a heavy burden for patients and society. Exercise is proposed as a safe, inexpensive, and accessible non-pharmacological treatment. To the author's knowledge this is the first systematic review to investigate the sleep-enhancing effects of exercise by focusing exclusively on controlled trials comprising poor sleepers only and examining interventions consistent with national guidelines. Using a narrative synthesis, this review aimed to identify whether exercise improves objective and subjective sleep outcomes for people with insomnia. Five papers including participants with insomnia disorder, and six papers including participants with insomnia symptoms were identified through electronic database searches (CINAHL plus, PsycINFO, EMBASE, MEDLINE, SPORTDiscus, CENTRAL) and quality assessed using the Clinical Trial Assessment Measure. We found that exercise interventions led to improvements in subjective sleep quality for people with insomnia disorder and insomnia symptoms. However, exercise only improved objective and subjective measures of sleep continuity (sleep onset latency and sleep efficiency) for people presenting with insomnia symptoms, with a reduction in sleep onset latency being the most consistently observed effect across studies. The reliability of significant findings is reduced by methodological limitations. Recommendations are made to improve the quality of future research.