Objective:

Night eating syndrome (NES) is characterized by a time-delayed pattern of eating relative to sleep, where most food is consumed in the evening and night. This study aimed to investigate the clinical significance of NES and nocturnal snacking by exploring the relationship between NES and (1) obesity,(2) binge eating disorder (BED) and (3) psychological distress.

Subjects:

One hundred and eighty bariatric surgery candidates, 93 members of a non-surgical weight loss support group and 158 general community respondents (81 males/350 females, mean age: 45.8±13.3 years, mean body mass index (BMI): 34.8±10.8 and BMI range: 17.7–66.7).

Methods:

NES diagnosis required within the previous 3 months:(1) no appetite for breakfast,(2) consumption of⩾ 50% of daily energy after 1900 hours and (3) sleep difficulties⩾ 3 nights/week. Nocturnal snacking (awakening to eat) was recorded. Validated questionnaires assessed BED, symptoms of depression, appearance dissatisfaction (AD) and mental health-related quality of life (MHQoL). NES and binge eating (BE)(⩾ 1 episode/week) were confirmed by interview.

Results:

NES criteria were met by 11.1% of the total cohort. Across all groups, BE (P= 0.001), BMI (P= 0.003) and male gender (P= 0.013) explained 10% of NES variance. Individuals with co-morbid NES and BE reported similarly elevated psychological distress as other binge eaters. NES alone was not associated with psychological distress. Those with NES who consumed nocturnal snacks reported poorer MHQoL (P= 0.007) and greater depressive symptoms (P= 0.039) and hunger (P= 0.013) than others with NES. Low MHQoL (P= 0.007) and male gender (P= 0.022) explained 27% of the variance in the nocturnal snacking group.

Discussion:

In this study, NES was positively associated with BMI, BE and male gender. Elevated psychological distress was only apparent in those who consumed nocturnal snacks. Further characterization and understanding of the clinical significance of NES and nocturnal snacking is required.