Emotion dysregulation predicts poor sleep, eating disorder symptoms and their relationship in female university students

Introduction: Patients with anorexia nervosa frequently experience interrupted sleep and early morning awaking, although they rarely complain of it (Crisp, 1967; Crisp et al., 2009). Notwithstanding, epidemiological evidence of the co-occurrence of eating disorders and insomnia are lacking. Instead, results of several studies suggest that the experimental induction of hunger produces increased wake time and reduced slow wave sleep (e.g. Ohno, Sakurai, 2008). This disruptive effect is probably due to the shared biochemical pathways between sleep and feeding. Actually, the peptide orexin produced by the Lateral Hypothalamic Area neurons, is involved in the regulation of both the feeding behavior and the sleep/wake cycle (e.g. Saper et al., 2005). Furthermore it is also related to emotional processes, since efferent pathways from the amygdala to the LHA orexin neurons have been evidenced and orexin production has been demonstrated to be activated by emotional events (e.g. Le Doux, 2007; Sakuray, 2007). The present study aimed at assessing the existence of a relationship between insomnia and eating disorders symptoms and to evaluate whether this relationship is accounted for or modulated by emotion dysregulation. The dysfunctional regulatory strategy examined was the expressive suppression (e.g. Gross, 2009). Method: 476 female university students (mean age = 23.22; S.D = 2.85) volunteered for participating to the study filling in the Disordered Eating Questionnaire (DEQ, Lombardo et al., 2004, for assessing the presence and intensity of eating restriction), the Contour Drawing Rating Scale (CDRS, Thompson & Gray, 1995, a pictorial measure of body dissatisfaction), the Insomnia Severity Index (ISI, Bastien et al., 2001, for assessing the severity of insomnia during the previous two weeks), the Emotional Regulation Questionnaire (ERQ, Gross, John, 2003, which includes a measure of the emotional suppression). Results: Relationships were tested through structural equation modelling. In the model with best fit indices (CFI = 0.96; TLI = 0.95; RMSEA = 0.05; SRMSR = 0.04), Emotional suppression predicts insomnia severity and Emotional suppression and Insomnia severity both predicts Restrictive eating. Conclusion: Results evidence that severity of insomnia is related to restrictive eating behaviour and mediates the relationship between suppression of emotion and restrictive eating in a wide non-clinical sample.