Subjective Sleep Debt Is Correlated with Body Fat Percentage Independent of Sleep Duration

No study has investigated whether subjective sleep debt (i.e., the gap between self estimations of sleep duration and sleep requirement) is linked to body fat mass. We studied 20,531 Swedish adults aged between 36 and 78 years (mean age: 60.9 ± 8.5 years, 56.6% women). Self-reported sleep duration and sleep needed for feeling fully rested (both in hours/day) were obtained by questionnaire. Subjective sleep debt per day was calculated by subtracting the value of sleep requirement with sleep duration. Fat mass was estimated by bioelectrical impedance analysis. Body fat percentage was calculated based on fat mass (kg) per total body mass (kg). Analysis of covariance (adjusting for age, gender, and self-reported sleep duration) was utilized to test the body fat percentage differences between hours of sleep debt, followed with Bonferroni corrections for multiple comparisons. Compared to those without subjective sleep debt, adults reporting a sleep debt of 2 hours and 3 hours or more were respectively associated with a 0.9 (95% CI: 0.5, 1.3) and 2.2 (95% CI: 1.4, 3.1) higher percentage of body fat mass (both p < 0.001). The corresponding differences when comparing these two groups to those reporting 1-hour sleep debt were 1.4 (95% CI: 1.0, 1.8) and 2.7 (95% CI: 1.9, 3.5), (both p < 0.001). The results suggest that subjective sleep debt of greater than one hour per day is associated with significantly higher body fat percentage.