Orexin and sleep quality in anorexia nervosa: Clinical relevance and influence on treatment outcome

Sleep disturbances in anorexia nervosa

INTRODUCTION

Sleep is crucial for physical and psychological health, and disturbances are closely linked to psychiatric disorders, making their management essential for improving treatment outcomes and preventing relapse. Although sleep disturbances are implicated in psychopathology of eating disorders, its role in anorexia nervosa (AN) remains unclear. This review aimed to characterise sleep in AN.

METHODS

A systematic search was conducted in four scientific databases, including papers from inception to 25 May 2024. A machine learning algorithm (ASReview) was utilised to screen titles and abstracts for eligibility. Sleep quantity, architecture, and quality were investigated. Meta-analyses were conducted to investigate the difference between patients with AN and healthy controls (HC) in total sleep time (TST), wake after sleep onset (WASO), sleep onset latency (SOL), sleep efficiency, Sleep Stage 1, 2, slow wave sleep, rapid eye movement (REM) sleep and REM latency. Certainty of evidence was assessed using the GRADE approach.

RESULTS

Out of 67 potentially eligible papers, 31 were included in this review, with 15 in the meta-analyses. Statistically significant average mean differences were found for TST (-32.1 min [95% CI: -50.9, -13.4]), WASO (19.0 min [95% CI: -2.4, 40.3]), and sleep efficiency (-4.4% [95% CI: -7.9, -0.9]). Additionally, Sleep stage 1 was significantly increased (2.4% [95%-CI: 0.05, 4.7]), while REM sleep was reduced (-2.1% [95%-CI: -4.2, -0.02]). Subgroup analysis showed that TST and WASO did not improve significantly after weight restoration.

CONCLUSION

Sleep in patients with AN is impaired, with lower TST and sleep efficiency, higher WASO, more time in stage 1 sleep, and less in REM. Weight restoration alone may not improve sleep. While more research is needed, substantial accompanying sleep disturbances in AN justifies addressing these in current treatment practice, also because of the chronic character of AN and importance of sleep for long term (mental) health.

The potential use of daridorexant in eating disorders: beyond the treatment of insomnia?

A strong interplay exists between sleep and dietary habits, and sleep disturbances have been repeatedly documented in individuals with eating disorders (EDs). The orexin system - implicated in sleep regulation, energy homeostasis, and food reward - may represent a mechanist link between sleep alterations and disordered eating behaviors. Daridorexant is a dual orexin receptor antagonist (DORA) recently approved for the treatment of insomnia, with demonstrated efficacy and tolerability. Owing to its action on orexin neurons, the compound represents an intriguing option for addressing both sleep-related and core symptoms of EDs. By inhibiting motor hyperactivity, daridorexant may reduce excessive physical exercise in individuals with anorexia nervosa (AN) restricting type. Additionally, the compound may exert anti-binge effects, suggesting broad applicability in binge ED, bulimia nervosa, and binge/purging AN. In this framework, daridorexant emerges as a promising therapeutic option, offering a multifaceted approach to improving circadian rhythms, energy balance, and overall quality of life in individuals with diverse ED subtypes.

Inclusion of hypocretin-1 improved performance of poor sleep quality prediction for elderly patients with acute ischemic stroke: a prospective cohort study

Background

Hypocretin-1 is a vital neurotransmitter in regulating the sleep-wake cycle and provides neuroprotection against cerebral ischemia. We aims to develop a poor sleep quality predictive model for elderly population with acute ischemic stroke.

Methods

A total of 183 consecutively elderly patients were included in the prospective cohort study. Sleep quality was assessed by the Pittsburgh Sleep Quality Index (PSQI). Cerebrospinal fluid samples were taken within 24 h of acute ischemic stroke onset. After selecting optimal predictors via univariate analysis and bootstrapped stepwise logistic regression, the predictive model was developed. The models were internally validated and evaluated comprehensively via discrimination, calibration, and clinical utility.

Results

The prevalence of poor sleep (PSQI >7) was 64.5% among elderly individuals experiencing acute ischemic stroke. The study developed a predictive model using hypocretin-1, hypertension, stroke history, the National Institutes of Health Stroke score, and depression. Adding hypocretin-1 (as continuous variable) significantly improved the model performance greatly, as the area under the receiver operating characteristic curve increased from 0.799 to 0.845 (p < 0.001). The optimal cutoff value for hypocretin-1 was 74.94 pg/mL. Adding hypocretin-1 (as binary variable) significantly improved the model performance greatly, as the AUC increased from 0.799 to 0.857 (p < 0.001).

Conclusion

Reduced cerebrospinal fluid levels of hypocretin-1 at admission were an independent poor sleep quality predictor and the model demonstrated superior performance. The combination of hypocretin-1 could offer valuable prognostic information for post-stroke sleep quality in elderly patients with acute ischemic stroke.

Bidirectional associations between insomnia symptoms and eating disorders: A two-wave longitudinal study among Chinese college students

Previous literature suggests a link between insomnia symptoms and eating disorders (EDs), yet empirical data on the temporal associations between these two variables are lacking. This study aimed to explore the bidirectional associations between insomnia symptoms and EDs in a population of college students. A total of 11,010 college students were assessed initially from October 17 to 29, 2023, and again 6 months later from April 15 to 24, 2024. EDs were assessed using the Short Form of the Eating Disorder Examination Questionnaire (EDE-QS), while insomnia symptoms were measured through a three-item questionnaire addressing difficulty initiating sleep, difficulty maintaining sleep, and early morning awakening. Our findings indicated that insomnia symptoms at baseline was significantly associated with increased odds of EDs six months later. Moreover, EDs at baseline were significantly predict insomnia symptoms at the six-month follow-up. This study identifies prospective bidirectional relationships between insomnia symptoms and EDs among college students, offering insights that may inform educational and clinical approaches to preventing and treating insomnia symptoms and EDs.

Sleep quality in eating disorders: A systematic review and meta-analysis

Eating disorders (ED) are psychological disorders characterized by dangerous eating behaviours, including protracted fasting and binge eating. Mental disorders comorbidities (e.g., anxiety and depression), as well as sleep difficulties, are common and might interfere with treatment response. This work investigated sleep quality, circadian preferences, and sleep disorders in ED patients compared to healthy controls (HC) and the impact of ED treatment on patients' sleep. A literature search on Pubmed, Web of Science, Medline, and PsychInfo included 27 studies. Random effect analyses were performed (sample eating disorders = 711; sample healthy controls = 653) and subgroup analyses were calculated based on the ED subgroups: Anorexia Nervosa, Bulimia Nervosa, Binge Eating Disorder. Whole sample analyses showed poorer physiological and subjective sleep quality in patients. Subgroup analyses showed that poorer physiological sleep was present only in anorexia nervosa. Two studies reporting circadian preferences and sleep disorders showed higher evening preference in patients and no differences in apnea prevalence between patients and healthy controls, respectively. Some studies suggested that specialized eating disorder treatments (e.g., Cognitive Behavioural Therapy for ED) can improve sleep quality in patients. Although these findings highlight poorer sleep in patients with ED compared to healthy controls, the mechanisms underlying sleep alterations in eating disorders remain to be identified.

Responses to bright light exposure in individuals with binge-spectrum eating disorders characterized by high dietary restraint and negative affect

OBJECTIVE

Circadian rhythm disruptions are associated with binge eating, can be causal of negative mood, and may be corrected with bright light exposure. A subtype of individuals with binge-spectrum eating disorders are characterized by combined high dietary restraint and negative affect. These individuals have higher eating disorder psychopathology and poorer treatment response. We aimed to test the targeted effects of morning bright light exposure on individuals with binge-spectrum eating disorders, hypothesizing significant reductions in binge eating for those characterized by high dietary restraint and negative affect.

METHODS

Participants (N = 34 females with binge-eating disorder and bulimia nervosa) used a morning bright light and normal light for 10 consecutive days each, in randomized order. They completed the Change in Eating Disorder Symptoms (CHEDS) scale at baseline, day 12 (when they switched lamps), and day 22. We conducted moderation analyses, clustering data by person, controlling for order, and examining the effect of light condition on binge eating according to baseline restraint and negative affect.

RESULTS

At high levels of combined dietary restraint and negative affect, participants experienced a reduction in binge eating and food preoccupation following exposure to morning bright light. There were no changes in restrictive eating, body preoccupation, body dissatisfaction, or body checking following exposure to morning bright light for these individuals.

DISCUSSION

These findings suggest that morning bright light may be a useful adjunct to empirically supported eating disorder treatments that target binge eating, especially for individuals characterized by the difficult to treat restraint/negative affect subtype.

PUBLIC SIGNIFICANCE

At high levels of combined dietary restraint and negative affect, participants with binge-spectrum eating disorders experienced a reduction in binge eating and food preoccupation following exposure to morning bright light. These findings suggest that morning bright light may be a useful adjunct to empirically supported eating disorder treatments that target binge eating, especially for individuals characterized by the difficult-to-treat restraint/negative affect subtype.

Similarities and differences regarding acute anorexia nervosa and semi-starvation: does behavioral thermoregulation play a central role?

Objective

To clarify the association between acute anorexia nervosa (AN) and semi-starvation (SS) by focusing on similarities and differences in physiology, mood, and behavior.

Method

A comparison of published literature between these two groups.

Results

Both groups show similar hormonal and metabolic changes in response to caloric restriction and extreme weight loss (~25%). Associated changes result in a reduced body temperature (Tcore-low). Maintenance of body temperature within a specific range is crucial to survival. However, both groups cannot activate autonomic strategies to maintain their Tcore-low, such as increasing metabolic rate, constricting skin blood vessels, or shivering. Furthermore, Tcore-low increases the individuals' "coldness sensations" throughout the body, hence the frequent reports from ANs and SSs of "feeling cold." To eliminate these uncomfortable "coldness sensations" and, importantly, to maintain Tcore-low, ANs, and SSs "select" different thermoregulatory behavioral strategies. It is proposed that the primary differences between AN and SS, based on genetics, now manifest due to the "selection" of different thermo-regulatory behaviors. AN patients (ANs) "select" hyperactive behavior (HyAc), which increases internal metabolic heat and thus assists with maintaining Tcore-low; in harmony with hyperactive behavior is a lively mood. Also related to this elevated arousal pattern, ANs experience disrupted sleep. In contrast, SS individuals "select" a passive thermo-behavioral strategy, "shallow torpor," which includes reduced activity, resulting in energy conservation. In addition, this inactivity aids in the retention of generated metabolic heat. Corresponding to this lethargic behavior, SS individuals display a listless mood and increased sleep.

Conclusion

Initial similarities between the two are attributable to physiological changes related to extreme weight loss. Differences are most likely attributable to genetically programmed "selection" of alternate thermoregulatory strategies, primarily to maintain Tcore-low. However, if acute AN is prolonged and evolves into a chronic condition, AN will more closely align with starvation and more precisely reflect SS symptomology.

The Role of Food Addiction and Lifetime Substance Use on Eating Disorder Treatment Outcomes

Food addiction (FA) and substance use (SU) in eating disorders (ED) have been associated with a more dysfunctional clinical and psychopathological profile. However, their impact on treatment outcomes has been poorly explored. Therefore, this transdiagnostic study is aimed at examining whether the presence of FA and/or SU is associated with treatment outcomes in patients with different ED types. The results were not able to reveal significant differences in treatment outcomes between patients with and without FA and/or SU; however, the effect sizes suggest higher dropout rates in the group with both FA and SU. The predictive models of treatment outcomes showed different features associated with each group. High persistence (i.e., tendency to perseverance and inflexibility) was the personality trait most associated with poor treatment outcomes in patients without addictions. High harm avoidance and younger age at ED onset were the variables most related to poor outcomes in patients with FA or SU. Finally, in the group with both addictive behaviors (FA and SU), the younger patients presented the poorest outcomes. In conclusion, our results suggest that, regardless of presenting addictive behaviors, patients with ED may similarly benefit from treatment. However, it may be important to consider the differential predictors of each group that might guide certain treatment targets.

Differences in sleep patterns between patients with anorexia nervosa and healthy controls: a cross-sectional study

BACKGROUND

Sleep difficulties are common in patients with anorexia nervosa (AN), but objective assessments have mostly been performed in hospital and laboratory settings. We aimed to identify differences in sleep patterns between patients with AN and healthy controls (HC) in their free-living environments, and potential associations between sleep patterns and clinical symptoms in patients with AN.

METHODS

This cross-sectional study analyzed 20 patients with AN prior to them starting outpatient treatment and 23 HC. Sleep patterns were measured objectively using an accelerometer (Philips Actiwatch 2) for 7 consecutive days. Average sleep onset, sleep offset, total sleep time, sleep efficiency, wake after sleep onset (WASO) and mid-sleep awakenings lasting ≥ 5 min were compared between patients with AN and HC using nonparametric statistical analyses. Associations of sleep patterns with body mass index, eating-disorder symptoms, eating-disorder-associated impairment, and symptoms of depression were assessed in the patient group.

RESULTS

Compared with HC, patients with AN had shorter WASO [median (interquartile range(IQR)): 33 vs. 42 min], but a longer average duration of mid-sleep awakenings lasting ≥ 5 min [median (IQR): 9 vs. 6 min, p = 0.006] and had more nights with no sleep (six nights in four patients with AN vs. zero nights in HC). There were no differences between patients with AN and HC regarding other sleep parameters and no significant correlations between sleep patterns and clinical parameters in patients with AN. However, HC presented a Intraindividual variability pattern that was closer to a normal distribution, whereas patients with AN tended to either have very regular or large variability in sleep onset time (AN; n = 7 < 25th percentile and n = 8 > 75th percentile vs. HC; n = 4 < 25 percentile and n = 3 > 75th percentile) during the week of sleep recordings.

CONCLUSION

Patients with AN seem to spend more time awake during the night and have more nights without sleep than do HC, even though their average weekly sleep duration did not differ from that in HC. The intraindividual variability in sleep pattern seems to be an important parameter that should be assessed when studying sleep in patients with AN. Trial registration ClinicalTroals.gov. Identifier: NCT02745067. Registered: April 20, 2016.

Exploring the Relationship between Disordered Sleep and Mood in Male Anorexia Nervosa: An Actigraphy Study

Eating disorders (EDs), including anorexia nervosa (AN), are severe psychological disorders that affect individuals' eating behaviours and body perception. Previous research has shown that people with EDs often report poorer sleep. Some literature has suggested that it is mood dysregulation that mediates the link between EDs and sleep. However, the majority of previous studies only focused on females, while male ED patients have been overlooked. Therefore, the present study aimed to investigate the relationships between EDs, mood, and sleep among male ED patients. Using a mixture of actigraphy recordings and self-reported questionnaires, the current study analysed a total 33 adult male participants diagnosed with AN. The participants first wore an actigraphy device for seven continuous days, following which their ED severity and mood were assessed by the Eating Disorder Examination Questionnaire (EDE-Q) and Depression Anxiety Stress Scale (DASS), respectively. The descriptive actigraphy results suggested that, similar to females, males with AN also showed disturbed sleep, including insomnia, sleep fragmentation, low sleep efficiency, and increased napping sessions. However, when ED severity was correlated against actigraphy data and mood, no significant relationships were found between them. Thus, it was suggested that future studies may investigate discrete ED symptoms instead of global ED severity interacting with sleep and mood. Overall, this study represents an initial step in the investigation of EDs and sleep and mood dysregulation among an under-represented sample.

Targeting the orexin/hypocretin system for the treatment of neuropsychiatric and neurodegenerative diseases: from animal to clinical studies

Orexins (also known as hypocretins) are neuropeptides located exclusively in hypothalamic neurons that have extensive projections throughout the central nervous system and bind two different G protein-coupled receptors (OX1R and OX2R). Since its discovery in 1998, the orexin system has gained the interest of the scientific community as a potential therapeutic target for the treatment of different pathological conditions. Considering previous basic science research, a dual orexin receptor antagonist, suvorexant, was the first orexin agent to be approved by the US Food and Drug Administration to treat insomnia. In this review, we discuss and update the main preclinical and human studies involving the orexin system with several psychiatric and neurodegenerative diseases. This system constitutes a nice example of how basic scientific research driven by curiosity can be the best route to the generation of new and powerful pharmacological treatments.

Engagement of the brain orexin system in activity-based anorexia behaviour in mice

While excessive physical activity is common amongst anorexia nervosa (AN) patients, contributing to their low body weight, little is known about the underlying biology and effective treatments targeting the hyperactivity are lacking. Given the role of orexin in arousal, physical activity and energy expenditure, we sought to investigate i) the extent to which orexin neurons are activated during severe anorectic state in the activity-based anorexia (ABA) mouse model, and ii) if the dual orexin receptor antagonist suvorexant can reduce physical activity during ABA. The Fos-TRAP2 technique enable us to visually capture active neurons (Fos expressing) during severe anorectic state in the ABA mouse model, and by immunohistochemistry, determine the extent to which these active neurons are orexin positive. In addition, suvorexant was administered peripherally to ABA mice and running activity was monitored. We found that a large population of orexin neurons in the hypothalamus are activated by ABA and that peripheral administration of suvorexant decreases food anticipatory activity in these mice. We conclude that orexin may be a suitable target to treat hyperactivity in AN and recommend further studies to examine the efficacy of suvorexant in aiding AN patients to control their drive for hyperactivity.

The contribution of sleep to anorexia nervosa severity

PURPOSE

Anorexia nervosa (AN) is associated with poor sleep and altered circadian rhythms. Evidence is unclear as to whether these features relate to ongoing psychiatric symptoms of AN, or are merely concomitant with low weight. In this study, we sought to evaluate subjective sleep quality and sleep-wake preferences in a sample of individuals with lifetime AN. Furthermore, we aimed to examine whether sleep quality would significantly predict AN symptom severity, after accounting for demographic features and negative emotions (depression, anxiety and stress).

METHODS

Adults with a lifetime diagnosis of AN (n = 96) or no lifetime psychiatric diagnoses (NC; n = 246) completed an online survey assessing demographics, sleep quality, circadian sleep-wake preferences, eating disorder symptoms, and negative emotions.

RESULTS

AN participants reported significantly poorer sleep quality overall, including increased sleep disturbances, use of sleep medications, and daytime dysfunction, as compared to NC participants. Groups did not differ significantly in circadian sleep-wake preferences. Regression analysis showed that among AN participants, sleep quality and negative emotions significantly predicted AN symptom severity, while sex and body mass index (BMI) did not.

CONCLUSION

The findings demonstrate that poor sleep quality was associated with more severe symptoms of AN, even when accounting for negative emotions and BMI. Future research should investigate causal interactions between sleep quality and AN symptom severity longitudinally and across different recovery stages.

LEVEL OF EVIDENCE

Level III-Cohort and case-control analytic studies.

Subjective sleep disorders and daytime sleepiness in patients with restrictive type anorexia nervosa and effects on quality of life: a case-control study

To evaluate sleep disorders and daytime drowsiness in a cohort of patients affected by anorexia nervosa and their impact on health-related quality of life. We evaluated patients affected by restricting-type of anorexia nervosa (AN-R) and healthy controls by the Pittsburgh Sleep Quality Index (PSQI), Epworth Sleepiness Scale, Beck Depression Index. We also used the Short-Form Health Survey (SF-36) questionnaire to assess the quality of life in both AN-R and controls. Twenty-eight out of 34 AN-R patients (82.3%) in contrast with ten out of 34 healthy subjects (29.4%) had a pathological PSQI score compared to HC (p < 0.0001). The overall PSQI score (p < 0.001), sleep quality (p < 0.001), sleep duration (p = 0.02), sleep efficiency (p = 0.002), sleep disturbances (p = 0.03) and daytime dysfunction (p = 0.004) were significantly higher in AN-R than in controls. SF36 showed significantly reduced scores of standardized physical components (p = 0.01) and standardized mental components (p < 0.001), physical function (p < 0.001), physical role (p < 0.001) and general health (p < 0.001), vitality (p < 0.001), social functioning (p  < 0.001) emotional role (p = 0.001) and mental health (p < 0.001) in AN-R. We found a significant correlation between the PSQI score and both the physical role (r = - 0.35, p = 0.03) and level of education (r = 0.38, p = 0.02). Our data showed reduced overall sleep quality without excessive daytime sleepiness in AN-R. Sleep quality correlated significantly with quality of life (physical role) and level of education.

The Central Role of Hypothermia and Hyperactivity in Anorexia Nervosa: A Hypothesis

Typically, the development of anorexia nervosa (AN) is attributed to psycho-social causes. Several researchers have recently challenged this view and suggested that hypothermia and hyperactivity (HyAc) are central to AN. The following hypothesis will attempt to clarify their role in AN. Anorexia nervosa patients (ANs) have significantly lower core temperatures (T_core) compared to healthy controls (HCs). This reduced temperature represents a reset T_core that needs to be maintained. However, ANs cannot maintain this T_core due primarily to a reduced basal metabolic rate (BMR); BMR usually supplies heat to sustain T_core. Therefore, to generate the requisite heat, ANs revert to the behavioral-thermoregulatory strategy of HyAc. The majority of ANs (~89%) are reportedly HyAc. Surprisingly, engagement in HyAc is not motivated by a conscious awareness of low T_core, but rather by the innocuous sensation of "cold- hands" frequently reported by ANs. That is, local hand-thermoreceptors signal the brain to initiate HyAc, which boosts perfusion of the hands and alters the sensation of "cold-discomfort" to one of "comfort." This "rewarding" consequence encourages repetition/habit formation. Simultaneously, hyperactivity increases the availability of heat to assist with the preservation of T_core. Additionally, HyAc induces the synthesis of specific brain neuromodulators that suppress food intake and further promote HyAc; this outcome helps preserve low weight and perpetuates this vicious cycle. Based on this hypothesis and supported by rodent research, external heat availability should reduce the compulsion to be HyAc to thermoregulate. A reduction in HyAc should decrease the production of brain neuromodulators that suppress appetite. If verified, hopefully, this hypothesis will assist with the development of novel treatments to aid in the resolution of this intractable condition.

Executive functions in binge spectrum eating disorders with comorbid compulsive buying

OBJECTIVE

The aims were to explore if bulimic spectrum disorders (BSD) patients, who also present comorbid compulsive buying (CB), could represent a specific subtype considering its neuropsychological performance; to present a descriptive analysis of different clinical features; and to explore how these variables could influence treatment outcome. It was hypothesised that the comorbid group will present worse neuropsychological performance that will lead to a worse treatment outcome.

METHOD

The study has a longitudinal design. Women (N = 75) diagnosed with BSD, BSD + CB and Healthy Controls (HC); completed an evaluation of: cognitive flexibility, decision making, eating disorder (ED) symptomatology, psychopathological state and personality traits.

RESULTS

BSD + CB was the group with the most severe clinical profile, worst treatment outcome and higher neuropsychological impairment, than other groups. Path-analysis evidenced that deficits in decision making were associated with bad treatment outcome, while deficits in flexibility with the presence of the comorbidity. Self-directedness and novelty seeking were associated with the neuropsychological performance and the comorbidity.

CONCLUSION

BSD + CB exhibit a worse clinical and neuropsychological profile that seems to be related with the treatment outcome, which should be taken into account for the establishment of specific treatment approaches.

Rapid response is predictive of treatment outcomes in a transdiagnostic intensive outpatient eating disorder sample: a replication of prior research in a real-world setting

OBJECTIVE

There is a growing call to identify specific outcome predictors in real-world eating disorder (ED) treatment settings. Studies have implicated several ED treatment outcome predictors [rapid response (RR), weight suppression, illness duration, ED diagnosis, and psychiatric comorbidity] in inpatient settings or randomized controlled trials of individual outpatient therapy. However, research has not yet examined outcome predictors in intensive outpatient programs (IOP). The current study aimed to replicate findings from randomized controlled research trials and inpatient samples, identifying treatment outcome predictors in a transdiagnostic ED IOP sample.

METHOD

The current sample comprised 210 consecutive unique IOP patient admissions who received evidence-based ED treatment, M(SD)_Duration = 15.82 (13.38) weeks. Weekly patient measures of ED symptoms and global functioning were obtained from patients' medical charts.

RESULTS

In relative weight analysis, RR was the only significant predictor of ED symptoms post treatment, uniquely accounting for 45.6% of the predicted variance in ED symptoms. In contrast, baseline ED pathology was the strongest unique predictor of end-of-treatment global functioning, accounting for 15.89% of predicted variance. Baseline factors did not differentiate patients who made RR from those who did not.

CONCLUSIONS

Consistent with findings in more controlled treatment settings, RR remains a robust predictor of outcome for patients receiving IOP-level treatment for EDs. Future work should evaluate factors that mediate and moderate RR, incorporating these findings into ED treatment design and implementation.

LEVEL OF EVIDENCE

Level IV, uncontrolled intervention.

The case for investigating a bidirectional association between insomnia symptoms and eating disorder pathology

Many people with eating disorders (EDs) report symptoms of insomnia (i.e., frequent difficulty falling asleep, staying asleep, and/or early morning wakening) and sleep problems have been linked to alterations in eating behaviors; however, mechanisms of these bidirectional associations remain poorly understood and under researched. This is a problem because higher insomnia symptom severity is a risk factor for the onset and perpetuation of anxiety, mood, trauma, and substance use disorders and, potentially, ED symptoms. Furthermore, insomnia symptoms may hinder recovery and increase relapse rates following successful psychotherapy. In this article, we describe potential mechanisms underlying bidirectional associations between insomnia and eating psychopathology that may contribute to the etiology and maintenance of both disorders. We suggest novel directions for future research to characterize the association between dysregulated sleep and ED symptoms and to evaluate impacts of insomnia symptoms on relapse and recovery for people with co-occurring pathology. Finally, we discuss options for testing the incorporation of existing evidence-based treatments for insomnia disorder (e.g., Cognitive-Behavioral Therapy for Insomnia) with ED care. Overall, insomnia symptoms present a promising intervention point for ED treatment that has not been systematically tested, yet would be highly feasible to address in routine clinical care.

Hypocretin (Orexin) Replacement Therapies

Twenty-two years after their discovery, the hypocretins (Hcrts), also known as orexins, are two of the most studied peptidergic systems, involved in myriad physiological systems that range from sleep, arousal, motivation, homeostatic regulation, fear, anxiety and learning. A causal relationship between activity of Hcrt and arousal stability was established shortly after their discovery and have led to the development of a new class of drugs to treat insomnia. In this review we discuss the many faces of the Hcrt system and examine recent findings that implicate decreased Hcrt function in the pathogenesis of a number of neuropsychiatric conditions. We also discuss future therapeutic strategies to replace or enhance Hcrt function as a treatment option for these neuropsychiatric conditions.

Late and Instable Sleep Phasing is Associated With Irregular Eating Patterns in Eating Disorders

BACKGROUND

Sleep problems are common in eating disorders (EDs).

PURPOSE

We evaluated whether sleep-phasing regularity associates with the regularity of daily eating events.

METHODS

ED patients (n = 29) completed hourly charts of mood and eating occasions for 2 weeks. Locomotor activity was recorded continuously by wrist actigraphy for a minimum of 10 days, and sleep was calculated based on periods of inactivity. We computed the center of daily inactivity (CenDI) as a measure of sleep phasing and consolidation of the daily inactivity (ConDI) as a measure of daily sleep rhythm strength. We assessed interday irregularities in the temporal structure of food intake using the standard deviation (SD) of frequency (IFRQ), timing (ITIM), and interval (IINT) of food intake. A self-evaluation of other characteristics included mood, anxiety, and early trauma.

RESULTS

A later phasing of sleep associated with a lower frequency of eating (eating frequency with the CenDI rho = -0.49, p = .007). The phasing and rhythmic strength of sleep correlated with the degree of eating irregularity (CenDI with ITIM rho = 0.48, p = .008 and with IINT rho = 0.56, p = .002; SD of CenDI with ITIM rho = 0.47, p = .010, and SD of ConDI with IINT rho = 0.37, p = .048). Childhood Trauma Questionnaire showed associations with variation of sleep onset (rho = -0.51, p = .005) and with IFRQ (rho = 0.43, p = .023).

CONCLUSIONS

Late and variable phasing of sleep associated robustly with irregular pattern of eating. Larger data sets are warranted to enable the analysis of diagnostic subgroups, current medication, and current symptomatology and to confirm the likely bidirectional association between eating pattern stability and the timing of sleep.

Neuroendocrinology of reward in anorexia nervosa and bulimia nervosa: Beyond leptin and ghrelin

The pathophysiology of anorexia nervosa (AN) and bulimia nervosa (BN) are still poorly understood, but psychobiological models have proposed a key role for disturbances in the neuroendocrines that signal hunger and satiety and maintain energy homeostasis. Mounting evidence suggests that many neuroendocrines involved in the regulation of homeostasis and body weight also play integral roles in food reward valuation and learning via their interactions with the mesolimbic dopamine system. Neuroimaging data have associated altered brain reward responses in this system with the dietary restriction and binge eating and purging characteristic of AN and BN. Thus, neuroendocrine dysfunction may contribute to or perpetuate eating disorder symptoms via effects on reward circuitry. This narrative review focuses on reward-related neuroendocrines that are altered in eating disorder populations, including peptide YY, insulin, stress and gonadal hormones, and orexins. We provide an overview of the animal and human literature implicating these neuroendocrines in dopaminergic reward processes and discuss their potential relevance to eating disorder symptomatology and treatment.

Reduced Plasma Orexin-A Concentrations are Associated with Cognitive Deficits in Anorexia Nervosa

Orexins/hypocretins are neuropeptides implicated in numerous processes, including food intake and cognition. The role of these peptides in the psychopathology of anorexia nervosa (AN) remains poorly understood. The aim of the current study was to evaluate the associations between plasma orexin-A (OXA) concentrations and neuropsychological functioning in adult women with AN, and a matched control group. Fasting plasma OXA concentrations were taken in 51 females with AN and in 51 matched healthy controls. Set-shifting was assessed using the Wisconsin Card Sorting Test (WCST), whereas decision making was measured using the Iowa Gambling Task (IGT). The AN group exhibited lower plasma OXA levels than the HC group. Lower mean scores were obtained on the IGT in AN patients. WCST perseverative errors were significantly higher in the AN group compared to HC. In both the AN and HC group, OXA levels were negatively correlated with WCST non-perseverative errors. Reduced plasma OXA concentrations were found to be associated with set-shifting impairments in AN. Taking into consideration the function of orexins in promoting arousal and cognitive flexibility, future studies should explore whether orexin partly underpins the cognitive impairments found in AN.

Other Specified Feeding or Eating Disorders (OSFED): Clinical heterogeneity and cognitive-behavioral therapy outcome

BACKGROUND

with the DSM-5 new eating disorders (EDs) diagnostic subtypes were identified within the Other Specified Feeding or Eating Disorders (OSFED) category, which have so far been under-researched. Objectives of this study were to examine differential features among OSFED subtypes, exploring short-term cognitive-behavioral therapy (CBT) response and identifying clinical predictors of therapy outcome.

METHODS

the sample included 176 female patients diagnosed with OSFED [82 atypical anorexia nervosa (atypical-AN), 57 purging disorder (PD), and 37 subthreshold bulimia nervosa (sub-BN)]. Assessment included eating-related, psychopathological and personality measures.

RESULTS

results showed similar clinical and personality profiles between the diagnostic subtypes, with hardly any differences, only observable in the core symptoms of each diagnosis. The sub-BN group was the one which showed more social impairment. Regarding treatment outcome, the three groups did not reveal significant differences in remission rates, therapeutic adherence or dropout rates, reaching rates of dropout from 36.8% to 50% (p = .391). However, different ED subtype predictors appear related with full remission or dropout risk, specifically personality traits.

CONCLUSIONS

our results suggest that OSFED patients may benefit similarly from the same CBT outpatient group approach. However, high dropout rates and low motivation seems to be an important limitation and challenge for future approaches.

Orexin/hypocretin and dysregulated eating: Promotion of foraging behavior

At its discovery, orexin/hypocretin (OX) was hypothesized to promote food intake. Subsequently, with the identification of the participation of OX in numerous other phenomena, including arousal and drug seeking, this neuropeptide was proposed to be involved in highly motivated behaviors. The present review develops the hypothesis that the primary evolutionary function of OX is to promote foraging behavior, seeking for food under conditions of limited availability. Thus, it will first describe published literature on OX and homeostatic food intake, which shows that OX neurons are activated by conditions of food deprivation and in turn stimulate food intake. Next, it will present literature on excessive and binge-like food intake, which demonstrates that OX stimulates both intake and willingness to work for palatable food. Importantly, studies show that binge-like eating can be inhibited by OX antagonists at doses far lower than those required to suppress homeostatic intake (3 mg/kg vs. 30 mg/kg), suggesting that an OX-based pharmacotherapy, at the right dose, could specifically control dysregulated eating. Finally, the review will discuss the role of OX in foraging behavior, citing literature which shows that OX neurons, which are activated during the anticipation of food reward, can promote a number of phenomena involved in successful foraging, including food-anticipatory locomotor behavior, olfactory sensitivity, visual attention, spatial memory, and mastication. Thus, OX may promote homeostatic eating, as well as binge eating of palatable food, due to its ability to stimulate and coordinate the activities involved in foraging behavior.

Short-Term Treatment Outcomes and Dropout Risk in Men and Women with Eating Disorders

This study compared treatment outcomes between men and women with eating disorders (EDs) and analysed clinical predictors of treatment outcome. Our sample consisted of 131 male and 131 female ED patients who underwent cognitive behavioural therapy treatment. ED severity, personality and psychopathology were assessed using standard instruments. We found that the risk of dropout was higher for men with bulimia nervosa (BN) than for women with BN and that men with BN and other specified feeding and EDs were more likely to obtain full remission in comparison with their female counterparts. Predictive models of treatment outcome indicated that higher scores in novelty seeking were a shared factor associated with higher risk of dropout and not obtaining full remission for both men and women with ED. However, only in men, younger age and lower scores in reward dependence predicted higher dropout. Contrastingly, higher persistence scores were predictors of full remission. This study reinforces the effectiveness of using outpatient cognitive behavioural therapy as treatment as usual for men with ED. Nonetheless, placing greater emphasis on strategies targeting gender-specific issues could enhance outcomes. Copyright © 2017 John Wiley & Sons, Ltd and Eating Disorders Association.

Neurobiochemical and psychological factors influencing the eating behaviors and attitudes in anorexia nervosa

The aim of this study was to determine the characteristic features which contribute to inappropriate eating attitudes in people suffering from anorexia nervosa, based on an analysis of recent data. Factors influencing these attitudes have a genetic, neurobiological, biochemical, affective-motivational, cognitive, and behavioral background. Another important issue addressed in the paper is a description of the mechanism leading to continuous dietary restrictions. The altered activity of neurotransmitters modulating patients’ moods after the consumption of food and a disturbed responsiveness to enterohormones enhance affective-motivational and cognitive aspects which, in turn, impede the improvement of eating behaviors. An understanding of the mechanisms behind the factors affecting the maintenance of inappropriate eating attitudes may contribute to greater effectiveness in the treatment of anorexia nervosa.

Sleep and Eating Disorders

Insomnia is related to an increased risk of eating disorders, while eating disorders are related to more disrupted sleep. Insomnia is also linked to poorer treatment outcomes for eating disorders. However, over the last decade, studies examining sleep and eating disorders have relied on surveys, with no objective measures of sleep for anorexia nervosa or bulimia nervosa, and only actigraphy data for binge eating disorder. Sleep disturbance is better defined for night eating syndrome, where sleep efficiency is reduced and melatonin release is delayed. Studies that include objectively measured sleep and metabolic parameters combined with psychiatric comorbidity data would help identify under what circumstances eating disorders and sleep disturbance produce an additive effect for symptom severity and for whom poor sleep would increase risk for an eating disorder. Cognitive behavior therapy for insomnia may be a helpful addition to treatment of those with both eating disorder and insomnia.

Sleep Patterns Before and After Weight Restoration in Females with Anorexia Nervosa: A Longitudinal Controlled Study

OBJECTIVE

To assess sleep patterns in female patients with anorexia nervosa before and after weight restoration.

METHODS

Sleep patterns were measured objectively using a Sense Wear Armband before and after weight restoration in 50 female patients with anorexia nervosa, and in 25 healthy females.

RESULTS

At baseline, patients with anorexia nervosa exhibited lower total sleep time and sleep onset latency than controls, the former apparently associated with baseline BMI, duration of illness and age. However, after weight restoration, total sleep time and sleep onset latency were similar to controls, despite the persistence of longer periods of wake after sleep onset.

DISCUSSION

In patients with anorexia nervosa, total sleep time and sleep onset latency appears to be reduced. This sleep disturbance seems to be influenced by the duration and severity of malnutrition, and appears to normalize with weight restoration. Even though a discontinuous sleep pattern seems to persist, this finding should be discussed with patients. Copyright © 2016 John Wiley & Sons, Ltd and Eating Disorders Association.