Moderating Effect of Daylight Exposure on the Relationship Between Physical Activity and Sleep in Patients with Upper Digestive Cancer: An Exploratory Study.

ABSTRACT

OBJECTIVES: To examine the moderating effect of daylight exposure on physical activity and objective sleep quality, using wearable actigraph devices. METHODS: We recruited 324 patients with either gastric or esophageal cancer. Actigraphs were used to measure all objective data including daylight exposure, physical activity, and sleep quality. Pearson's correlation coefficients were used to examine the relationships among demographic data, disease attributes, physical activity, daylight exposure, and sleep. The Hayes PROCESS macro with the regression bootstrapping method was employed to analyze the moderating effect of daylight exposure on the relationship between physical activity and sleep. RESULTS: Sleep efficiency correlated positively with physical activity, while "wake after sleep onset" correlated negatively with physical activity and mean lux. Mean lux and light >500 lux significantly moderated the association between physical activity and sleep efficiency (P = .002 in both cases). Similarly, mean lux and light >500 lux significantly moderated the association between physical activity and "wake after sleep onset" (P = .002 and .001, respectively). CONCLUSION: Both average daylight exposure and time of exposure to >500 lux act as moderators of physical activity and objective sleep quality in patients with gastric or esophageal cancer. Healthcare practitioners should encourage patients with cancer to engage in daily outdoor physical activity. Further intervention studies are needed to verify the combined effect of daytime light exposure and physical activity on improving sleep quality. IMPLICATIONS FOR NURSING PRACTICE Healthcare practitioners should encourage patients with cancer to engage in daily outdoor physical activity. Further intervention studies are needed to verify the combined effect of daytime light exposure and physical activity on improving sleep quality.