Participants will be randomly assigned to one of two conditions. One group will partake in a moderate-intensity physical activity training regimen. The other group will act as a non-exercise attention-control comparison group. Each group will undergo its assigned treatment for 12 months. Sleep quantity and quality will be measured objectively using in-home polysomnography. Subjective sleep quality and health-related quality of life measures will be evaluated with questionnaires. All measurements will be performed at the beginning of the study, Month 6, and Month 12.