Sleep quality is differentially related to adiposity in adults.

OBJECTIVES: Sleep duration is associated with adiposity in adults. Abdominal adiposity specifically is strongly correlated with metabolic alterations, however, the relationships between abdominal adiposity and sleep quality are incompletely understood. The purpose of this study is to test the hypothesis that abdominal adiposity is related to poor sleep quality while total adiposity is not; and to explore whether pathways, including immune system and hypothalamic-pituitary-adrenal axis, link abdominal adiposity to poor sleep quality.

METHODS: Subjects were 101 men and women aged 38.88 ± 11.96 years with body mass index between 29.35 ± 6.93 kg/m. Subjective sleep quality was determined by the Pittsburgh Sleep Questionnaire Index (PSQI). Body composition was determined by dual energy X-ray absorptiometry. Saliva and blood samples were collected for assessment of cortisol and markers of inflammation. In a cross-sectional study design, correlation analysis was conducted to determine the relationships between poor sleep quality and adiposity. Participants were stratified based on PSQI score to evaluate differences in main outcomes between subjects with normal (NSQ; PSQI ≤ 5) vs poor sleep quality (PSQ; PSQI > 5).

RESULTS: Poor sleep quality was related to greater visceral fat (r = 0.26; p < 0.05), but not total fat. The PSQ group had greater visceral fat compared to the NSQ group (1.11 ± 0.83 kg vs 0.79 ± 0.62 kg; p < 0.05), however, there was no difference in total fat mass (33.18 ± 14.21 kg vs 29.39 ± 13.03 kg; p = 0.24). The PSQ group had significantly greater leptin (1.37 ± 0.07 ng/ml vs 1.08 ± 0.08 ng/ml; p < 0.05), but hypothalamic-pituitary-adrenal axis activity did not differ between the PSQ and NSQ groups.

CONCLUSIONS: Poor sleep quality is associated with greater visceral adiposity and leptin secretion. Further research is needed to probe potential cause and effect relationships among visceral adipose tissue, leptin, and sleep quality.