THE JOINT EFFECT OF INSOMNIA WITH SHORT SLEEP DURATION AND LEISURE-TIME PHYSICAL ACTIVITY ON THE RISK OF CARDIOVASCULAR AND ALL-CAUSE MORTALITY (THE HUNT STUDY)

Introduction: Previous studies indicate that insomnia with short sleep duration is associated with a significantly increased risk of all-cause and cardiovascular mortality. However, no previous study has investigated whether leisure-time physical activity modifies this association. The aim of this study was therefore to investigate if leisure-time physical activity modifies the association between insomnia with short sleep duration and all-cause and cardiovascular mortality. Methods: This prospective study included 40,368 adults who participated in the second survey of the HUNT study in 1995-1997. The study population comprised adults aged ≥20 years who responded to questionnaires on lifestyle, socio-demographics, insomnia symptoms, and sleep duration. Cox regression was used to estimate adjusted hazard risks (HRs) with 95% confidence interval (CI) for the association of insomnia, sleep duration, and leisure-time physical activity with all-cause and cardiovascular mortality. Results: Among 40,376 adult participants included in the study, 5,223 (12.9%) had insomnia symptoms and 6.9% reported short sleep duration. During a 17-year follow-up period, 6686 participants died (2575 due to cardiovascular disease). Compared to the reference category of physically active people without insomnia symptoms and normal sleep duration, people with insomnia with short sleep had an HR for all-cause mortality of 1.86 (95% CI 1.38-2.50) if they were physically inactive and an HR of 1.19 (95% CI 0.94-1.29) if they were physically active. Physically inactive people without insomnia and normal sleep duration had an HR of 1.16 (95% CI 1.02-1.34). The corresponding HRs for cardiovascular mortality were 1.78 (95% CI: 1.10-2.41), 1.26 (95% CI: 0.69-1.87), and 1.05 (95% CI 0.53-1.68); respectively. Conclusion: This study shows that meeting recommended levels of physical activity modified some of the increased risks of all-cause and cardiovascular mortality among participants with insomnia accompanied by short sleep duration. These findings suggest that promoting physical activity could reduce adverse health effects outcomes of insomnia with short sleep duration. Keywords: insomnia; sleep duration; leisure-time physical activity; all-cause mortality; cardiovascular mortalit