The effect of sleep loss on insulin resistance and blood pressure (BP) might be modified by the presence of obesity. We therefore assessed the association of sleep loss with insulin resistance and BP by weight status in healthy adolescents.Design and method:
A cross-sectional sample of 384 male adolescents, aged between 15 and 18 years, was recruited for this study. Brachial arterial BP was measured in the supine position using digital BP monitor with an appropriate size cuff. Fasting blood sample was collected for the measurement of lipid and glucose profiles by standard techniques. Insulin resistance was evaluated based on the homeostatic model assessment of insulin resistance (HOMA-IR). The quality and patterns of sleep were measured using the Pittsburgh Sleep Quality Index.Results:
The subjects who stayed up later at night (after 12 pm.) had significantly higher systolic and diastolic BP, pulse rates, fasting glucose, insulin, and HOMA-IR compared to the other subjects. There was a significant association between the delayed bedtime and systolic BP (β = .102, p = .041), diastolic BP (β = .213, p < .001), and HOMA-IR (β = .261, p < .001) after adjusting for age and height. A graded association was found between weight status and HOMA-IR and systolic and diastolic BP (p for trend < .001). The synergistic effect of the delayed bedtime and obesity was significant on HOMA-IR (F = 4.62, p = .033), but not on systolic BP (F = 1.23, p = .281) and diastolic BP (F = 1.22, p = .310), by two-way ANOVA. Path analysis indicated that the delayed bedtime had an adverse impact on HOMA-IR and diastolic BP, and the elevated HOMA-IR contributed to the increase of diastolic BP indirectly (direct, β = .192; indirect, β = .051; total, β = .242).Conclusions:
These results suggest that sleep loss may affect autonomic nervous activity, and leads to the increase of insulin resistance and BP even in healthy adolescents, independent of obesity.