A recent study published in the British Journal of Cancer suggests walking could improve the quality of sleep for lung cancer patients. The researchers said a similar link is seen in breast and colorectal cancer patients.
The trial investigated the effects of a 12-week exercise intervention including home-based walking exercise training and weekly exercise counseling on 111 lung cancer patients ranging in age from late 30s to early 80s. Almost two-thirds had Stage I cancer. Participants were randomly allocated to receive the intervention or usual care. 
- objective sleep
- total sleep time
- sleep efficiency
- sleep onset latency
- wake after sleep onset
- subjective sleep
- rest-activity rhythms
Outcomes were assessed at baseline and 3 and 6 months after intervention.
“Walking is safe, feasible and effective for patients. Just walk!” senior author Chia-Chin Lin, a nursing professor at Taipei Medical University, told Reuters Health. “With advances in lung cancer treatment, survival improves significantly,” she said. “Any interventions that can improve symptoms and quality of life are valuable.” 
Patients were divided into two groups:
- Walk at a moderate intensity for 40 minutes three times a week
- Record their exercise after every session
- Participate in weekly exercise counseling sessions
- Wore wrist monitors that collected subjective and objective sleep data
- Receive usual medical care
- Opportunity for exercise counseling
“Traditionally, physical activities have not been emphasized in lung cancer patients due to concerns about fragility and limited cardiopulmonary function,” Lin said. “However, we found that home-based walking programs may be a safe and feasible way to improve emotion and sleep quality.”
The study also looked at circadian rhythms; researchers measured how consistently patients woke and went to sleep at the same times each day. They found that exercise was linked to improved sleep quality. People whose circadian rhythms were most disrupted got the most benefit.
These rhythms are believed to influence several aspects of health such as heart rate, sleep, inflammation, and metabolism. The altered circadian function can increase the risk for a number of chronic diseases, Lin said.