Reallocating time to physical activity and sleep: associations with quality of life in cancer survivors

PURPOSE: Quality of life (QOL) is an important psychosocial outcome in cancer survivors (CS). Physical activity (PA), reducing sedentary time (ST), and sleep can help CS improve QOL; however, these behaviors are commonly studied in isolation, despite their interdependence during the 24-h day (i.e., time in one activity cannot increase without time decreasing in another activity). This study examined the effects of reallocating time between moderate to vigorous PA (MVPA), light PA, ST, and sleep on QOL in a mixed sample of CS. METHODS: A cross-sectional sample of CS (N = 73) diagnosed with breast (29.7%), colorectal (33.8%), or other (36.5%) cancer. MVPA, light PA, and ST were measured using the activPAL™ accelerometer, and sleep duration using the Actiwatch™ accelerometer. Both were worn for 7 days, 24 h per day. QOL was self-reported using the Functional Assessment of Cancer Therapy-General (FACT-G) questionnaire. Isotemporal substitution models were used to reallocate 30 min between activities. Statistical significance was set at p < .05. RESULTS: Participants accumulated, M = 24.0 ± 18.9 min/day of MVPA, 291.7 ± 100.4 min/day of light PA, 593.1 ± 108.3 min/day of ST, and 486.6 ± 57.6 min/night of sleep. Isotemporal substitution effects for reallocating time between MVPA, light PA, ST, and sleep were not significantly associated with QOL. CONCLUSIONS: Findings from this study suggest that among CS who are achieving adequate levels of PA and sleep, changes in 30 min of these activities may not impact QOL. Future studies should aim to recruit a larger, more representative sample and explore the role of bouted activity time.