Relationships of exercise timing with sleep, fatigue and rest–activity rhythms of lung cancer patients in Taiwan: An exploratory study

Objective: To explore the relationship of exercise timing (exercising close to bedtime, exercising in daylight and maintaining fixed exercise schedule) with sleep quality, fatigue and rest–activity rhythms among lung cancer patients in Taiwan. Methods: Results from 43 lung cancer patients who were assigned and adhered to the exercise intervention in a 12-week randomised controlled trial were analysed. The MD Anderson Symptom Inventory and Pittsburgh Sleep Quality Index (PSQI) were administered. Actigraphs were used to assess rest–activity rhythms (in-bed less than out-of-bed dichotomy index, I < O) and objective sleep parameters, including total sleep time (TST) and sleep onset latency (SOL). Results: Patients who exercised >4 hr before bedtime had significant improvement in fatigue (p <.0001), sleep quality (p =.012 for PSQI; p =.037 for TST; p =.017 for SOL) and rest–activity rhythms (p =.048 for I < O). Furthermore, patients who exercised with daylight exposure had a significant improvement in fatigue (p =.037) and sleep quality (p =.039 for PSQI). Conclusions: Exercising >4 hr before bedtime with daylight exposure is associated with improvement in rest–activity rhythms, sleep quality and fatigue in lung cancer patients. The causal relationship requires further investigation with experimental design.