Sleep duration and body mass index: moderating effect of self-perceived stress and age. Results of a cross-sectional...

The objective of this analysis was to assess whether the association between sleep duration and BMI and between sleep duration and waist circumference is moderated by age and self-perceived stress.

We analyzed data from 2034 participants enrolled in 2014 in the cross-sectional study Obesity in Romania Study-study of the prevalence of obesity and related risk factors in Romanian general population (ORO study).

Interaction between sleep duration, self-perceived stress and age, with BMI as dependent variable, was statistically significant after adjustment for demographic and lifestyle factors (p value for interaction 0.003). In participants without self-perceived stress, a linear negative association between sleep duration and BMI was observed only in those 18-39 years old (p = 0.049), with BMI decreasing in parallel with increased sleep duration. In participants with self-perceived stress, a U-shaped relationship was observed between BMI and sleep duration in those 40-64 years old, with higher BMI in those sleeping ≤ 6 h and ≥ 9 h/night compared to those sleeping > 6 and < 9 h/night (p = 0.002 and 0.005). Those ≥ 65 years old with self-perceived stress sleeping ≥ 9 h/night had a significantly higher BMI compared to those in other sleep duration categories (p = 0.041 vs. those sleeping ≤ 6 h/night and p = 0.013 vs. to those sleeping > 6 and < 9 h/night). No interaction between age, self-perceived stress and sleep duration, with waist circumference as dependent variable was observed.

In our sample, the association between sleep duration and BMI was moderated by self-perceived stress and age.