Sleep and physical activity in relation to all-cause, cardiovascular disease and cancer mortality risk.
Level 3 - non-randomized controlled study
Prospective observational cohort study with 11.1 years of follow-up
PubMed 34187783 · doi:10.1136/bjsports-2021-104046
What was done
Prospective cohort study analyzing 380,055 UK Biobank participants (mean age 55.9 ± 8.1 years, 55% women). Baseline physical activity (PA) was categorized into high, medium, low, and no moderate-to-vigorous physical activity (MVPA). Sleep was categorized as healthy, intermediate, or poor based on a composite score covering chronotype, sleep duration, insomnia, snoring, and daytime sleepiness, yielding 12 PA-sleep combinations. Mortality risks were tracked for an average follow-up of 11.1 years across all-cause, total cardiovascular disease (CVD), CVD subtypes (coronary heart disease, haemorrhagic stroke, ischaemic stroke), total cancer, and lung cancer.
What was found
Sleep scores showed dose-response associations with all-cause, total CVD, and ischaemic stroke mortality. Compared with the high PA-healthy sleep reference group, the no MVPA-poor sleep group had the highest mortality risks: all-cause HR 1.57 (95% CI 1.35 to 1.82), total CVD HR 1.67 (95% CI 1.27 to 2.19), total cancer HR 1.45 (95% CI 1.18 to 1.77), and lung cancer HR 1.91 (95% CI 1.30 to 2.81). The deleterious associations of poor sleep with mortality outcomes, except for stroke, were amplified at lower physical activity levels.
Why it matters
This study shows that physical inactivity exacerbates the mortality risks associated with poor sleep, suggesting synergistic effects and supporting joint lifestyle interventions.
Limits
The observational design cannot establish causality. Physical activity and composite sleep characteristics were assessed at baseline and are subject to self-report misclassification and unmeasured changes over time. UK Biobank participants are also subject to a healthy volunteer selection bias.