Social jetlag predicts greater evening energy intake in a UK cohort

Social jetlag (SJL) describes the differences in sleep timing between workdays and weekends. In a 14-day longitudinal observational study, we explored the associations between SJL and energy intake on workdays and weekends. Healthy male and female participants residing in the UK [ n = 101] used a smartphone app to record dietary intake continuously during the study period, encompassing two working weeks and weekends. We hypothesised that higher SJL levels would be associated with greater energy intake after 16:00 h and that any such effect would be most evident in late chronotypes. We found that increasing SJL levels modified temporal energy intake in both female and male participants, while temporal patterns of energy intake differed by sex. The modifying effect of SJL differed slightly between weekdays and weekends. Inclusion of chronotype in the statistical models did not alter the associations between SJL and energy intake. Furthermore, the magnitude of the effect estimates was modest and, in caloric terms, unlikely to explain the higher risks of obesity and metabolic diseases previously associated with increasing SJL levels.