Rapid changes in night eating: considering mechanisms

Night eating in bipolar disorder

OBJECTIVE

Night eating syndrome (NES) involves reduced feeding during the day and evening hyperphagia sometimes accompanied by frequent nocturnal awakenings with conscious episodes of compulsive ingestion of food. Previously, NES has not been evaluated in bipolar disorder (BD). The objective of this study was to identify NES in euthymic BD patients.

PATIENTS/METHODS

Eighty BD patients and 40 controls were examined using the Night Eating Questionnaire, Hamilton Rating Scale for Depression and Anxiety, Young Mania Rating Scale, Functioning Assessment Short-Test and International Physical Activity Questionnaire. Sleep quality (Pittsburgh Sleep Quality Index), daytime sleepiness (Epworth Sleepiness Scale), severity of insomnia (Insomnia Severity Index) and morning-evening preference (Morningness-Eveningness Questionnaire) were also evaluated.

RESULTS

BD patients presented NES in 8.8% while the controls showed no NES. Patients with and without NES were not different with respect to gender, disease duration, smoking, heavy drinking, body mass index, waist-to-hip ratio and neck circumference. BD patients with NES scored higher for functioning as well as for the following specific components: occupational functioning, financial issues, interpersonal relationships and leisure time. They also had more anxiety, higher insomnia severity and worse sleep quality. Furthermore, BD patients with NES were more evening type.

CONCLUSION

NES occurs more frequently in BD patients than in controls. BD patients with NES present more disease-related manifestations such as more anxiety, poorer functioning and worse sleep parameters. Patients with NES were more evening type. We speculate whether changing circadian preference in these patients can reduce NES.

Risk assessment of night-eating syndrome occurrence in women in Poland, considering the obesity factor in particular

INTRODUCTION

Night-eating syndrome (NES) involves uncontrolled and most often repeated binge eating during the night. It is related with mood disorders as well as sleep disorders and it may cause obesity. Risks related to NES are obesity, binge eating disorder, bulimia nervosa, affective disorders, and sleep disorders. The objective of this study is to analyze eating habits in terms of the risk assessment of NES occurrence in the population of women in the Masovian Voivodeship (in Poland).

PATIENTS AND METHODS

Six hundred and eleven women living in the Masovian Voivodeship participated in the study. The average age of the respondents was 22.7 years (median = 23.0; interquartile range = 3.0). The Night Eating Questionnaire (NEQ) was used to assess the risk of NES.

RESULTS

In the studied group of women, 1.3% of cases (N = 12) reached a NEQ total score of ≥25, which indicates a probability of 40.7% for NES, while 0.7% (N = 4) reached a score of ≥30, which indicates a probability of 72.2% for occurrence of this syndrome. The highest average total score was observed in the group of obese people. The level of education of the participants did not significantly affect the NEQ score. A weak correlation was observed between the place of residence variable and the mood/sleep subscale (r = 0.11, P < 0.01).

CONCLUSION

NES may be one of the causes of overweight and obesity; therefore, the need for further studies on this health issue is justified. It is worth pointing out that knowing the conditions responsible for the occurrence of NES, it is possible to suggest a prevention procedure for this condition.

The molecular clock as a metabolic rheostat

Circadian clocks are biologic oscillators present in all photosensitive species that produce 24-h cycles in the transcription of rate-limiting metabolic enzymes in anticipation of the light-dark cycle. In mammals, the clock drives energetic cycles to maintain physiologic constancy during the daily switch in behavioural (sleep/wake) and nutritional (fasting/feeding) states. A molecular connection between circadian clocks and tissue metabolism was first established with the discovery that 24-h transcriptional rhythms are cell-autonomous and self-sustained in most tissues and comprise a robust temporal network throughout the body. A major window in understanding how the clock is coupled to metabolism was opened with discovery of metabolic syndrome pathologies in multi-tissue circadian mutant mice including susceptibility to diet-induced obesity and diabetes. Using conditional transgenesis and dynamic metabolic testing, we have pinpointed tissue-specific roles of the clock in energy and glucose homeostasis, with our most detailed understanding of this process in endocrine pancreas. Here, we review evidence for dynamic regulation of insulin secretion and oxidative metabolic functions by the clock transcription pathway to regulate homeostatic responses to feeding and fasting. These studies indicate that clock transcription is a determinant of tissue function and provide a reference for understanding molecular pathologies linking circadian desynchrony to metabolic disease.

Night eating syndrome: implications for severe obesity

Night eating syndrome (NES) was first identified in 1955 by Stunkard, a psychiatrist specialising in eating disorders (ED). Over the last 20 years considerable progress has been made in defining NES as a significant clinical entity in its own right and it has now been accepted for inclusion in the fifth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5) due for publication in 2013. NES is considered a dysfunction of circadian rhythm with a disassociation between eating and sleeping. Core criteria include a daily pattern of eating with a significantly increased intake in the evening and/or night time, as manifested by one or both of the following: at least 25% of food intake is consumed after the evening meal or at least two episodes of nocturnal eating per week. An important recent addition to core criteria includes the presence of significant distress and/or impairment in functioning. Stunkard's team recommend further investigation on the pathogenesis of NES, in particular its relationship with traumatic life events, psychiatric comorbidity, the age of onset of NES and course of NES over time. The relationship between NES and other ED also requires further clarification as night-eaters exhibit some features of other ED; previous guidance to separate NES from other ED may have hindered earlier characterisation of NES. Evidence from European and American studies suggests NES features strongly in populations with severe obesity. The complex interplay between depression, impaired sleep and obesity-related comorbidity in severely obese individuals makes understanding NES in this context even more difficult. This review examines evidence to date on the characterisation of NES and concludes by examining the applicability of current NES criteria to individuals with severe obesity.

Sleep and obesity: a focus on animal models

The rapid rise in obesity prevalence in the modern world parallels a significant reduction in restorative sleep (Agras et al., 2004; Dixon et al., 2007, 2001; Gangwisch and Heymsfield, 2004; Gupta et al., 2002; Sekine et al., 2002; Vioque et al., 2000; Wolk et al., 2003). Reduced sleep time and quality increases the risk for obesity, but the underlying mechanisms remain unclear (Gangwisch et al., 2005; Hicks et al., 1986; Imaki et al., 2002; Jennings et al., 2007; Moreno et al., 2006). A majority of the theories linking human sleep disturbances and obesity rely on self-reported sleep. However, studies with objective measurements of sleep/wake parameters suggest a U-shaped relationship between sleep and obesity. Studies in animal models are needed to improve our understanding of the association between sleep disturbances and obesity. Genetic and experimenter-induced models mimicking characteristics of human obesity are now available and these animal models will be useful in understanding whether sleep disturbances determine propensity for obesity, or result from obesity. These models exhibit weight gain profiles consistently different from control animals. Thus a careful evaluation of animal models will provide insight into the relationship between sleep disturbances and obesity in humans. In this review we first briefly consider the fundamentals of sleep and key sleep disturbances, such as sleep fragmentation and excessive daytime sleepiness (EDS), observed in obese individuals. Then we consider sleep deprivation studies and the role of circadian alterations in obesity. We describe sleep/wake changes in various rodent models of obesity and obesity resistance. Finally, we discuss possible mechanisms linking sleep disturbances with obesity.

Night eating syndrome: an overview

Objectives

The purpose of this review is to outline the nosographic characteristics of NES and the most reliable ethiopathogenetic theories in relation to the most recent evidence in the literature.

Key findings

The night eating syndrome (NES) is a disorder occurring at the stated time, that does not meet the criteria for any specific eating disorder. NES is characterized by a reduced feeding during the day, evening hyperphagia accompanied by frequent nocturnal awakenings associated with conscious episodes of compulsive ingestion of food and abnormal circadian rhythms of food and other neuroendocrine factors. Frequently it is associated with obesity and depressed mood. We highlight the therapeutic possibilities of some drugs, especially selective serotonin re-uptake inhibitors (SSRIs), which reduce the hyperactivity of the serotonin transporter in NES and significantly improve the clinical picture of this disease.

Conclusions

Night eating syndrome is of importance clinically because of its association with obesity. The recognition and effective treatment of NES may be an increasingly important way to treat a subset of the obese population. Treatment of the syndrome, however, is still in its infancy. One clinical trial has reported efficacy with the SSRI sertraline. Other treatments, such as the anticonvulsant topiramate, phototherapy, and other SSRIs, may also offer future promise. Particularly useful would be studies involving brain scans (magnetic resonance imaging or single-photon emission computed tomography) of patients with NES compared with the healthy population, to investigate more thoroughly the possible alterations involved in the pathogenesis of NES.