In the first description of the night eating syndrome (NES) 1955 by Stunkard et al. the criteria included (1) consumption of at least 25% of the total calories for the day after the evening meal, (2) sleeplessness, at least until midnight more than one half of the time and (3) morning anorexia with negligible food intake at breakfast. Further studies altered these criteria step by step, without ever relating to the changes already made by other authors. So today our knowledge about NES and its related features is based on an amazing variety of constructs merely referred to by the same term. However, there seems to be an agreement about a higher prevalence of the NES in overweight and obese treatment seeking samples. The relationship between NES, body weight and a possible influence of NES on overweight and obesity remains unclear and needs to be further examined. In addition to the research activities regarding NES as a possible eating disorder, sleep disorder specialists showed a growing interest in patients with sleeplessness and nocturnal eating episodes. New definitions were developed: the "night eating/drinking syndrome" (synonymous: NES), a disorder occurring mainly in infancy and early childhood but also seen in adults. Today the less restrictive concept "sleep related eating disorder" (SRED) eliminated the NES-concept, but also states a sleep disorder that is not clearly distinguishable from NES described by several authors as a possible eating disorder. In psychosomatic research the criteria of nocturnal eating (recurrent awakenings & getting up to eat) was included in the NES by a growing number of authors in the last 15 years. Based on this diversity of diagnostic criteria in two different fields of expertise a lot of research was done do investigate the prevalence of NES and further describe patients with NES. Today a meaningful summary of these findings is not possible and despite a growing number of research in NES and obesity the clinical relevance of the concept NES remains unclear. In this article diagnostic criteria so far will be summarized and a rough differentiation of NES to related constructs and disorders will be given.
