Associations Among Sleep, Emotional Eating, and Body Dissatisfaction in Adolescents.

The literature on adolescent sleep has shown a bidirectional relationship between sleep difficulties and altered eating habits, including emotional eating. However, it is unclear if this relationship is related to preexisting body concerns, or if poor sleep is the prime contributor to emotional eating patterns. This study therefore seeks to examine body dissatisfaction as a moderator of the sleep-emotional eating relationship in an at-risk sample. Adolescents (N = 106) presenting for overnight polysomnography self-reported on time-in-bed, insomnia, body dissatisfaction, and emotional eating. Less time-in-bed was correlated with a greater desire for thinness and greater insomnia severity was related to overall emotional eating and eating in response to anxiety, anger, and frustration and in response to depression. Moderation analyses revealed that the relationships between time-in-bed and eating in response to feeling unsettled (b = -.002, 95% CI[- .003, - .001], p < .005) and eating in response to anxiety, anger, and frustration (b = -.01, 95% CI[- .01, - .001], p < .05) were exacerbated by worse body dissatisfaction. Optimizing sleep may attenuate the risk for disordered eating, particularly for adolescents with high body dissatisfaction.

Vagus Nerve Stimulation Must Occur During Tactile Rehabilitation to Enhance Somatosensory Recovery.

Chronic sensory loss is a common and undertreated consequence of many forms of neurological injury. Emerging evidence indicates that vagus nerve stimulation (VNS) delivered during tactile rehabilitation promotes recovery of somatosensation. Here, we systematically varied the timing of VNS relative to tactile rehabilitation to determine the paradigm that yields the greatest degree of somatosensory recovery after peripheral nerve injury (PNI). The medial and ulnar nerves in rats were transected, causing chronic sensory loss. Eight weeks after injury, rats were given a VNS implant followed by four weeks of tactile rehabilitation sessions consisting of repeated mechanical stimuli to the previously denervated forepaw. Rats received VNS before, during, or after tactile rehabilitation. Delivery of VNS during rehabilitative training generates robust, significant recovery compared to rehabilitative training without stimulation (56 ± 14% improvement over sham stimulation). A matched amount of VNS before training, immediately after training, or two hours after training is significantly less effective than VNS during rehabilitative training and fails to improve recovery compared to rehabilitative training alone (5 ± 10%, 4 ± 11%, and -7 ± 22% improvement over sham stimulation, respectively). These findings indicate that concurrent delivery of VNS during rehabilitative training is most effective and illustrate the importance of considering stimulation timing for clinical implementation of VNS therapy.

Hypothalamic-pituitary-adrenal axis dysregulation and cortisol activity in obesity: A systematic review.

BACKGROUND: Although there is substantial evidence of differential hypothalamic-pituitary-adrenal (HPA) axis activity in both generalized and abdominal obesity, consistent trends in obesity-related HPA axis perturbations have yet to be identified. OBJECTIVES: To systematically review the existing literature on HPA activity in obesity, identify possible explanations for inconsistencies in the literature, and suggest methodological improvements for future study. DATA SOURCES: Included papers used Pubmed, Google Scholar, and the University of California Library search engines with search terms body mass index (BMI), waist-to-hip ratio (WHR), waist circumference, sagittal diameter, abdominal versus peripheral body fat distribution, body fat percentage, DEXA, abdominal obesity, and cortisol with terms awakening response, slope, total daily output, reactivity, feedback sensitivity, long-term output, and 11ß-HSD expression. STUDY ELIGIBILITY CRITERIA: Empirical research papers were eligible provided that they included at least one type of obesity (general or abdominal), measured at least one relevant cortisol parameter, and a priori tested for a relationship between obesity and cortisol. RESULTS: A general pattern of findings emerged where greater abdominal fat is associated with greater responsivity of the HPA axis, reflected in morning awakening and acute stress reactivity, but some studies did show underresponsiveness. When examined in adipocytes, there is a clear upregulation of cortisol output (due to greater expression of 11ß-HSD1), but in hepatic tissue this cortisol is downregulated. Overall obesity (BMI) appears to also be related to a hyperresponsive HPA axis in many but not all studies, such as when acute reactivity is examined. LIMITATIONS: The reviewed literature contains numerous inconsistencies and contradictions in research methodologies, sample characteristics, and results, which partially precluded the development of clear and reliable patterns of dysregulation in each investigated cortisol parameter. CONCLUSIONS AND IMPLICATIONS: The literature to date is inconclusive, which may well arise from differential effects of generalized obesity vs. abdominal obesity or from modulators such as sex, sex hormones, and chronic stress. While the relationship between obesity and adipocyte cortisol seems to be clear, further research is warranted to understand how adipocyte cortisol metabolism influences circulating cortisol levels and to establish consistent patterns of perturbations in adrenal cortisol activity in both generalized and abdominal obesity.