Background In adults, sleep has showed an important role on health namely in cardiovascular risk factors. The purpose of this cross-sectional study was to evaluate the association between sleep duration and blood pressure, at 13 years of age.

Methods We evaluated 1771 adolescents at 13 year old as part of a population-based cohort study (EPITeen). Sleep duration was estimated by the difference between self-reported usual bedtimes and wake-up times and adolescents were classified in three categories: ≤8.5 h (reference class), >8.5 h and <9.5 h and ≥9.5 h. Blood pressure (BP) was measured with a mercury sphygmomanometer using the auscultatory method, and hypertension was defined according to the American Academy of Pediatrics criteria. To evaluate the association between BP and sleep duration, OR and respective 95% CI, were computed, using the binary regression models adjusted for parents' education, BMI and caffeine intake.

Results The mean (SD) sleep duration was 9.04 (0.80) hours per day. The prevalence of hypertension was 22.4% and it was significantly higher among males (54.8% vs 45.2%; p=0.001). After adjustment, in females, a positive association was found between sleep duration and hypertension (>8.5 h and <9.5 h: OR=1.61, 95% CI 1.07 to 2.44; ≥9.5 h: OR=1.75, 95% CI 1.13 to 2.70). Among males an inverse association was found, significant only in those who slept ≥9.5 h (OR=0.62, 95% CI 0.40 to 0.95).

Conclusion Sleep duration was positively associated with the odds of hypertension occurrence in females, but the opposite association was found in males.