Descriptive epidemiology of objectively-measured, free-living sleep parameters in a rural African setting.
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, triaxial accelerometry data was collected over 9 days. Measures of sleep quantity and quality, and physical activity were extracted from valid minute-by-minute data. Adiposity indices were body-mass-index, waist circumference and conicity index. 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 h/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 preliminary qualitative data suggests that future studies should include more detailed data around contextual issues of sleep (social, cultural, economic, environment).
['Cook|Ian|I|http://orcid.org/0000-0001-5098-2936', 'Mohlabe|Matlawa|M|', 'Alberts|Marianne|M|']
D061725:Accelerometry D050154:Adiposity D000328:Adult D015444:Exercise D005260:Female D006801:Humans D008297:Male D008875:Middle Aged D009017:Morbidity D012424:Rural Population D012890:Sleep D012892:Sleep Deprivation D013019:South Africa D013997:Time Factors
Measurement Accelerometer Actigraphy Anthropometry Body composition Movement monitor