Night Eating Syndrome, circadian rhythms and seasonality. A study in a population of Italian university students

PURPOSE: The aim of this research was to assess the prevalence of Night Eating Syndrome (NES) in a university student population and to clear up the relationship between NES, depression and chronotype. The relation between NES and seasonality was also investigated. METHODS: The data were collected from a sample of 1136 students of the L'Aquila University, Italy. All subjects were invited to answer to the Sociodemographic Information Form and to take a self-report battery composed by four questionnaires: the Night Eating Questionnaire (NEQ), the Morningness Eveningness Questionnaire (MEQ), the Seasonal Pattern Assessment Questionnaire (SPAQ) and the Beck Depression Inventory (BDI). RESULTS: The 5.3% of our population (60 subjects) reached the criteria for NES. The distribution of chronotypes in the sample was: Morning Type 15.3%, Intermediate 64.3% and Evening Type 20.4%. The 36.7% of the participants reaching the criteria for NES, obtained low scores on the MEQ. The data indicated that NEQ and MEQ scores are significantly inversely correlated (r=-.22; p<.01, two-tailed test). The 3.6% of our population (41 subjects) reached the criteria for Seasonal Affective Disorder (SAD) and 10.7% for subclinical SAD (121 subjects). Furthermore, the 11.7% of subjects with NES presented SAD and the 5% presented Subclinical SAD. The data demonstrated that NES and Global Seasonality Score (GSS) are significantly associated (r=.22; p<0.01, two-tailed test). CONCLUSIONS: The main finding of this study is the strong relation between NES and eveningness dimension. Our results help to clear up the literature debate about the role of eveningness dimension in the night eating, suggesting that subjects with NES present a circadian delay, not only in the food intake, but in the entire functioning. At the best of one knowledge this study is the first one to examine the relationship between NES and seasonality. This research found preliminary evidence that, similarly to the findings of previous studies in subjects with Bulimia Nervosa (BN) and Binge Eating Disorder (BED), night eating symptoms may vary significantly across the seasons; subjects with NES experience seasonal variation in their mood and in their eating patterns.