• Total wake time at night, wake time after sleep onset, sleep latency, and percent of total sleep in stages 1, 2, 3, 4 and rapid eye movement as measured by in-home polysomnography collected at baseline, 6 months, and 12 months [ Time Frame: 12 months ] [ Designated as safety issue: No ]
  

• Subjective sleep quality, sleep duration, and sleep-onset latency as measured by the Pittsburgh Sleep Quality Index; [ Time Frame: 12 months ] [ Designated as safety issue: No ]
  
• Physical performance as measured by symptom-limited treadmill exercise testing; all measures collected at baseline, 6 months, and 12 months [ Time Frame: 12 months ] [ Designated as safety issue: No ]
  

Sleep deprivation is a common problem among older adults. It is often at the root of increased mortality and some psychiatric disorders. Regular participation in a medium-intensity exercise regimen may help people sleep better. This study will assess the effectiveness of a regular exercise program on improving sleep in older adults with moderate difficulty sleeping.

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.