Descriptive epidemiology of objectively-measured, free-living sleep parameters in a rural African setting.
Abstract Objectives To investigate the descriptive nature of objectively-measured, free-living sleep quantity and quality, and the relationship to adiposity, in a rural African setting in 145 adults (≥40 years, female: n=104, male: n=41). Wrist-mounted, tri-axial accelerometry data was collected over nine days. Measures of sleep quantity and quality, and physical activity were extracted from valid minute-by-minute data. From stature, body mass and waist circumference, body-mass-index and conicity index were calculated. Self-reported data included behavioural, health and socio-demographic variables. Community consultation followed the quantitative data analyses, for validation and interpretation of findings. Results Females had more nocturnal sleep than males (7.2 vs. 6.8 hours/night, p=0.0464) while males recorded more diurnal sleep time (p=0.0290). Wake after sleep onset and number of awakenings were higher in females, and sleep efficiency was higher in males (p≤0.0225). Sleep indices were generally similar between weekdays and weekends, except for sleep fragmentation index (p=0.0458). Sleep quantity, but not sleep quality was independently and inversely associated with adiposity (p=0.0453). Physical activity and morbidity measures were significantly and consistently associated with sleep and adiposity measures (p<0.0458). The qualitative data explained some of the unexpected associational directions of the independent variables correlated with sleep variables.