Exercise has been shown to improve sleep quality. This study was looked at the relationship between physical activity and subjective and objective sleep in midlife women. Physical activity was assessed with questionnaires and the level of activity was split into 3 domains. The first domain was labeled Active / Living and consisted of things like watching television and active transportation such as walking to work. The second domain was Household / Care-giving activities such as housework and child care. The last domain was Sports / Exercise which included participation in recreational activity or sports. The women's sleep was measured via in-home sleep study, daily sleep diaries, and questionnaires about their sleep.
The results showed that women who consistently participated in regular Sports / Exercise had better objective and subjective measurements of sleep, including sleep quality, sleep continuity, and depth, but not sleep duration. Women in this group also had reduced odds of meeting the diagnostic criteria for insomnia. This relationship was observed despite statistical adjustment for factors such as body mass index and other health behaviors. This association was not seen for those women in the domains of Active / Living and Household / Care-giving.
The relationship between the Sports / Exercise group and sleep was strongest when the pattern of activity existed over multiple years rather than just exercising immediately prior to the sleep assessment. In other words, regular exercise over many years may improve sleep more than sporadic exercise.