Raptin, a novel brain hormone links sleep health to body weight gain
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Raptin, a sleep-induced hypothalamic hormone, suppresses appetite and obesity
Sleep deficiency is associated with obesity, but the mechanisms underlying this connection remain unclear. Here, we identify a sleep-inducible hypothalamic protein hormone in humans and mice that suppresses obesity. This hormone is cleaved from reticulocalbin-2 (RCN2), and we name it Raptin. Raptin release is timed by the circuit from vasopressin-expressing neurons in the suprachiasmatic nucleus to RCN2-positive neurons in the paraventricular nucleus. Raptin levels peak during sleep, which is blunted by sleep deficiency. Raptin binds to glutamate metabotropic receptor 3 (GRM3) in neurons of the hypothalamus and stomach to inhibit appetite and gastric emptying, respectively. Raptin-GRM3 signaling mediates anorexigenic effects via PI3K-AKT signaling. Of note, we verify the connections between deficiencies in the sleeping state, impaired Raptin release, and obesity in patients with sleep deficiency. Moreover, humans carrying an RCN2 nonsense variant present with night eating syndrome and obesity. These data define a unique hormone that suppresses food intake and prevents obesity.
The impact of exercise on sleep and sleep disorders
Regular exercise provides a variety of health benefits, including enhanced sleep quality and reduced symptoms of sleep disorders. The complex interaction between sleep and physical activity involves various physiological and psychological processes. Exercise has a positive effect on sleep, but factors such as age, sex, and fitness level, and specific exercise aspects such as intensity, duration, and timing play crucial roles. Understanding these dynamic interactions is essential to gaining insight into how exercise benefits sleep in both healthy individuals and those with sleep disorders. Given the positive effects of moderate exercise on sleep and its potential as a therapeutic option, this narrative review highlights the extensive benefits of exercise on sleep and underscores its important role in overall health and wellness.
Simulating microgravity with 60 days of 6 degree head-down tilt bed rest compromises sleep
Astronauts in space often experience sleep loss. In the AGBRESA (Artificial Gravity Bed Rest) study, we examined 24 participants (mean age ± SD, 33 ± 9 years) during two months of 6o head-down tilt (HDT) bed rest, which is a well-established spaceflight analogue. Polysomnography was recorded during baseline (BDC-9), HDT (nights 1, 8, 30 and 58) and recovery (R, nights 1 and 12). Mixed ANOVAs with post-hoc step-down Bonferroni adjustment indicated that compared to BDC-9, arousals were increased, while sleep duration, N3, and sleep efficiency were all decreased during HDT. Significant quadratic associations between sleep duration and quality with time into HDT did not indicate adaptive improvements during the course of HDT. While sleep duration recovered quickly after the end of bed rest, participants still displayed protracted sleep fragmentation. We conclude that physiological changes caused by exposure to microgravity may contribute to persistent sleep deficits experienced during real space missions.
EEG-based headset sleep wearable devices
The rise of wearable technology has led to EEG-based sleep monitoring devices that use electrodes placed on the forehead, ear, or neck. These devices offer promising applications in clinical and healthy populations by comparing sleep patterns, monitoring intervention responses, and examining the relationship between sleep and lifestyle factors. Despite their potential, challenges like validation against polysomnography, regulatory hurdles, data privacy, and usability hinder clinical adoption. This review explores these devices, their applications, and integration challenges in clinical practice.
Dual orexin receptor antagonists as promising therapeutics for Alzheimer’s disease
We examine the relationship between sleep, glymphatics and Alzheimer’s disease (AD), and recent work questioning glymphatic clearance during sleep. We highlight a need for understanding glymphatic and/or other mechanism of clearance during sleep, and review glymphatic flow measurement methods. Further, we explore dual orexin receptor antagonists (DORAs) potential to mitigate AD sleep disturbances and enhance clearance. Further research could elucidate a linkage between DORAs, improved sleep and reducing AD pathophysiology.
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