Purpose: To examine longitudinal change in cardiorespiratory fitness and odds of incident sleep problems.
Methods: A cohort of 7368 men and 1155 women, age 20-85 yr, was recruited from the Aerobics Center Longitudinal Study. The cohort did not complain of sleep problems, depression, or anxiety at their first clinic visit. Cardiorespiratory fitness assessed at four clinic visits between 1971 and 2006, each separated by an average of 2-3 yr, was used as a proxy measure of cumulative physical activity exposure. Sleep complaints were made to a physician during follow-up.
Results: Across visits, there were 784 incident cases of sleep complaints in men and 207 cases in women. After adjusting for age, time between visits, body mass index, smoking, alcohol use, chronic medical conditions, complaints of depression or anxiety at each visit, and fitness at visit 1, each minute of decline in treadmill endurance (i.e., a decline in cardiorespiratory fitness of approximately 0.5 MET) between the ages of 51 and 56 yr increased the odds of incident sleep complaints by 1.7% (range = 1.0%-2.4%) in men and by 1.3% (range = 0.0%-2.8%) in women. Odds were ∼8% higher per minute decline in people with sleep complaints at visits 2 and 3.
Conclusions: The results indicate that maintenance of cardiorespiratory fitness during middle age, when decline in fitness typically accelerates and risk of sleep problems is elevated, helps protect against the onset of sleep complaints made to a physician.