Introduction: Despite increased recognition of the influence of sleep on weight loss, lifestyle interventions have paid little attention to sleep and its change with intervention. Moreover, available evidence on the relevance of sleep in weight loss interventions has been limited to self-reported sleep data. The purpose of these analyses was to examine the influence of a 12-mo behavioral weight loss intervention on objective and subjective sleep parameters and to evaluate whether changes in sleep were related to weight loss.
Hypothesis: We hypothesized that objective and subjective sleep measures would improve following the intervention and that improved sleep would be associated with greater weight loss.
Methods: A sample of 127 adults (89% female, 84% Caucasian, 51.8±9.7 y, 34.0±4.5 kg/m2) participated in a 12-mo standard behavioral weight loss intervention that included 24 group sessions. Sleep was assessed objectively at baseline and 12 mo with 5-7 days of actigraphy (Philips Actiwatch 2). Measures included total sleep time (total time spent asleep), sleep efficiency (percentage of time asleep while in bed), and the Fragmentation Index (restlessness during sleep). Subjective sleep quality was assessed with the Pittsburgh Sleep Quality Index (PSQI), yielding a global PSQI score (overall sleep quality) and individual PSQI factors (perceived sleep quality, sleep efficiency, daytime disturbance) were evaluated. Weight outcomes included the percentage of baseline weight lost at 12 mo and whether clinically significant weight loss (≥10%) was achieved. Analyses (repeated measures ANOVA, multiple linear regression, and binary logistic regression) were adjusted for age, sex, and race.
Results: The mean 12-mo weight loss was 9.1±8.1%, with 43% achieving at least 10% weight loss. No actigraphic sleep measures significantly changed from baseline to 12 mo. Overall sleep quality significantly improved over the 12 mo (6.4±3.6 to 5.9±3.1 [P=.02]), as did the PSQI factors of perceived sleep quality (P=.05) and sleep efficiency (P=.03). Baseline to 12-mo improvements in the Fragmentation Index and PSQI perceived sleep quality were associated with greater weight loss (β=.22 [P=.03] and β=.29 [P<.01]). Blunted improvements in the Fragmentation Index and the PSQI perceived sleep quality factor were associated with reduced odds of achieving at least 10% weight loss (OR=0.89 [P=.02] and OR=0.20 [P<.01]). No other sleep measures were associated with weight loss outcomes.
Conclusions: Following a behavioral intervention that resulted in clinically significant weight loss, only subjective sleep quality was improved. However, weight loss was optimized among adults whose sleep fragmentation decreased and sleep quality improved. Whether augmenting behavioral weight loss interventions with sleep-focused content would lead to greater weight loss remains to be determined.