The bidirectional association between physical activity and sleep in middle-aged and older adults: a prospective study based on polysomnography

Study Objectives: To examine the bidirectional association between physical activity (PA) and polysomnographically (PSG)-assessed sleep parameters characterized by total sleep time (TST), sleep onset latency (SOL), wake time after sleep onset (WASO), sleep efficiency and percentage of TST in N1, N2, and N3 stages and rapid eye movement (REM) sleep in middle-aged and older adults. Methods: Longitudinal study based on a subsample of the Wisconsin Sleep Cohort. Self-reported PA information was used to estimate the metabolic equivalents of task (MET-minutes/week) activity and in-laboratory PSG exams provided information on sleep parameters at baseline and after 3-11 years of follow-up between 2004 and 2015. Poisson and linear regression models controlling for confounders estimated associations of sleep outcomes with changes in PA. Results: A total of 424 participants (45.8% female; mean +/- SD age 60.1 +/- 7.5 years) were followed over an average of 5.0 +/- 1.6 years. Compared to baseline PA of <500 MET-minutes/week (reference category), 500 to 1500 MET-minutes/week of PA was associated with lower incidences of TST <6 hours (relative risk, RR: 0.49; 95% confidence interval, CI: 0.27; 0.88), WASO >60 minutes (RR: 0.58; 95% CI: 0.41; 0.82) and sleep efficiency <80% (RR: 0.61; 95% CI: 0.39; 0.94), adjusting for sociodemographic, health behaviors and medical conditions. No significant associations were observed between baseline sleep characteristics and changes in PA through the follow-up. Conclusion: In this prospective study, an intermediate level of PA at baseline predicted lower risk of incident short sleep time, higher WASO and lower sleep efficiency measured with PSG.