The Compositional associations of time spent in sleep, sedentary behaviour and physical activity with all-cause mortality
INTRODUCTION: Daily time spent in sleep, sedentary behaviour (SED), light intensity physical activity (LIPA), and moderate-to-vigorous intensity physical activity (MVPA) are compositional, co-dependent variables. The objective of this study was to use compositional data analysis (CoDA) to examine the relationship between the movement behaviour composition (daily time spent in sleep, SED, LIPA, and MVPA) and all-cause mortality risk. METHODS: 2,838 adult participants from the 2005-2006 cycle of the U.S. National Health and Nutrition Examination Survey were studied. Daily time spent in SED, LIPA, and MVPA were objectively determined by accelerometer. Time spent sleeping per night was self-reported. Survey data were linked with mortality data through to the end of December 2015. CoDA was used to investigate relationships between the movement behaviour composition and mortality. RESULTS: The movement behaviour composition was significantly associated with mortality risk. Time spent in MVPA relative to other movement behaviours was negatively associated with mortality risk (HR=.74; 95% CI [.67, .83]) while relative time spent in SED was positively associated with mortality risk (HR=1.75; 95% CI [1.10, 2.79]). Time displacement estimates revealed that the greatest changes in mortality risk occurred when time spent in MVPA was decreased and replaced with sleep, SED, LIPA, or a combination of these behaviours (HRs of 1.76 to 1.80 for 15 minute/day displacements). CONCLUSION: The daily movement behaviour composition was related to survival. Replacing MVPA or SED with any other movement behaviour was associated with an increase and decrease in mortality risk, respectively.