Identification of Night Eating Behaviour and Investigation into Its Characteristics in an Obese Population

Abstract

Background
Night Eating Syndrome (NES) was characterised in 2003 as comprising; morning anorexia, evening hyperphagia, night-time awakenings, consumption of high calorie snacks during awakenings and an absence of other eating disorders (ED).
Method
An identification study was conducted in a hospital–based UK obesity clinic with 81 individuals undertaking a diagnostic interview and completing a proposed screening tool. Full NES (n=7) and partial NES (n=24) individuals were combined into one Night Eating Behaviour (NEB) group (n=31) and compared to all other participants (n=50). NEB characteristics were identified through qualitative thematic analysis of interview data, based on techniques used by Grounded Theorists. NEB individuals (n=28) were compared with matched controls. In a separate prevalence study, night-eating, sleep quality and suspected Obstructive Sleep Apnoea (OSA) were estimated in 103 participants using the Pittsburgh Sleep Quality Index, Epworth Sleepiness Scale and a validated Night Eating Questionnaire. Correlational analysis was also performed.
Results
In the identification study, full NES was rare (9%). Comparison of the NEB and non-NEB group showed significant differences in mood (p=0.001), work status (p= 0.03), perceived lack of control over eating (p= 0.03) and variability in sleep duration (p<0.01). The study tool successfully identified NEB, but not other ED. Interview analysis identified the compulsive nature of night-eating and chaotic eating patterns. A variety of physical factors affected night-time awakenings. The matched control comparison showed no difference in levels of significant life events, childhood-onset obesity and poor sleep quality. Prevalence study results showed; suspected NES 14.6% (n=15), based on a lower cut score of >25, 3.9% (n=4), based on a higher cut score of >30, poor sleep quality 74% (n= 76) and suspected OSA 32% (n= 33). A strong relationship (r = 0.55, p = < 0.001) between night-eating and poor sleep quality was found, with day-time sleepiness having no influence over this relationship.
Conclusion
Comparison of the study findings with new NES criteria (2010) shows poor differentiation between NES and morbid obesity. In obese populations, a shift of focus is proposed to an alternative ‘Impaired Sleep Syndrome’ of which night-eaters may be a sub-group, often with severe depression. Night-eaters also exhibit too many features of other ED for this relationship to be ignored.