Fig. 1: A U-shaped association exists between sleep length and SBP/DBP is present even when adjusted for BMI.

Relationship between sleep length (A, B) and sleep quality (C, D) versus SBP and DBP, respectively, with (baseline model, red) and without adjustment for BMI (BMI adj model, blue). Data are expressed as β-estimate ± 95% CI, which are presented as the centre circle and corresponding error bars, respectively. P-values are estimated using multivariate logistic regression. *p < 0.05 versus sleep length of 7 h or a sleep quality score of 4–5, respectively, denoted by the solid grey triangle. Please see also Supplementary Table S1.