Researchers evaluated the relationship between poor sleep quality and high body mass index (BMI), exploring whether disordered eating (i.e. eating late at night and/or binge eating, which can occur at night) may partly explain the relationship.

330 people completed an online survey about their height and weight, recent sleep quality, and recent experiences of binge-eating and night-time eating.

Results showed that high BMI was shown to be related to shorter sleep duration, increased sleep latency (finding it harder to fall asleep), use of sleeping medication and worse binge-eating. Interestingly worse sleep quality increased the likelihood of more night-eating (night eating syndrome is a pattern of eating where people wake at night and act on cravings and urges to eat). Binge-eating was shown to partly mediate the relationship between worse sleep quality to higher BMI. People with night-eating and a high BMI showed worse sleep quality.

These results suggest that night- and/or binge-eating may partly explain the observed relationship between worse sleep quality and overweight/obesity. Thus, the relationship may simply reflect that overweight people are more likely to binge-eat while they wait for sleep to come, and this may contribute to weight gain over time. In addition, the results may indicate that eating rather than weight gain or obesity may be responsible for causing the sleep deficits in overweight people.