Can the relationship between overweight/obesity and sleep quality be explained by affect and behaviour?

PURPOSE: Sleep impairment is reported to be a consequence of overweight and obesity. However, the weight–sleep relationship can alternately be explained by demographics (e.g. age) and covariates (i.e. mood/affect and behaviour in overweight/obese people; e.g. night-eating). Thus, we examined the weight–sleep quality relationship after controlling for the effects of affect and common behaviour (i.e. night-eating, insufficient exercise, alcohol and electronic device use). METHODS: Online questionnaires asked 161 overweight, obese or normal-weight participants about their sleep quality, night-eating, physical activity, alcohol use, electronic device use and anxiety and depression at T0 (baseline) and T1 (3 months later). Height and weight and waist and hip circumference were objectively measured at T0 and T1, and physical activity was assessed over 24 h (using actigraphy) at T0 and T1. Hierarchical multiple regression analyses evaluated whether the weight measures (i.e. body-mass-index [BMI], waist-to-hip ratio [WHR] and obesity category [overweight/obese vs. normal-weight]) predicted sleep quality and its components at T0 and T1, after controlling demographics (at step 1) and covariates (affective distress and behaviour) at step 2, and entering weight measures at step 3; maximum 8 variables in the analyses. RESULTS: High BMI predicted several aspects of sleep quality after taking into account co-existing behaviour, affect and demographics: sleep disturbances at T0 and lower sleep efficiency at T1. WHR and obesity category did not predict any aspects of sleep quality. Several co-existing behaviour were related to or predicted sleep quality score and aspects of sleep quality including night-eating, alcohol use and electronic device use and affective symptoms (i.e. anxiety, depression). CONCLUSION: Results suggest that a person’s weight may impact on their sleep quality above and beyond the effects of their co-existing behaviour and affect, although their co-existing behaviour and affect may also adversely impact on sleep quality. LEVEL OF EVIDENCE: Level III, evidence obtained from well-designed cohort.