core body temperature circadian phase

The circadian clock is an evolutionarily-conserved molecular oscillator that enables species to anticipate rhythmic changes in their environment. At a molecular level, the core clock genes induce circadian oscillations in thousands of genes in a tissue-specific manner, orchestrating myriad biological processes. While previous studies have investigated how the core clock circuit responds to environmental perturbations such as temperature, the downstream effects of such perturbations on circadian regulation remain poorly understood...

Changes in lighting accompany modern urbanization trends and can lead to various pathologies based on circadian disturbances. In this study, we assessed the changes in the circadian rhythm of core body temperature (Tcore) and locomotor activity of Wistar-Kyoto rats (WKY) and spontaneously hypertensive rats (SHR) following exposure to different lighting conditions: extended light phase of the day (16 h-8 h, 20 h-4 h, 24 h-0 h), light pollution, monochromatic light, and bright light therapy. The telemetry data was collected after experimental lighting conditions during periods with standard lighting (12 h of light and 12 h of darkness) and was processed using linear and cosinor analysis...

Substantial evidence suggests that the circadian decline of core body temperature (CBT) triggers the initiation of human sleep, with CBT continuing to decrease during sleep. Although the connection between habitual sleep and CBT patterns is established, the impact of external body cooling on sleep remains poorly understood. The main aim of the present study is to show whether a decline in body temperatures during sleep can be related to an increase in slow wave sleep (N3). This three-center study on 72 individuals of varying age, sex, and BMI used an identical type of a high-heat capacity mattress as a reproducible, non-disturbing way of body cooling, accompanied by measurements of CBT and proximal back skin temperatures, heart rate and sleep (polysomnography)...

We have investigated the effects that partial-sleep-restriction (PSR0 , 4-h sleep retiring at 02:30 and waking at 06:30 h for two consecutive nights) have on 07:30 and 17:00 h cognitive and submaximal weightlifting; and whether this performance improves at 17:00 h following a 13:00 h powernap (0, 30 or 60-min). Fifteen resistance-trained males participated in this study. Prior to the experimental protocol, one repetition max (1RM) bench press and back squat, normative habitual sleep and food intake were recorded...

Sleep in extreme situations has been little studied. The artist Abraham Poincheval (AP) is known for his performances in confined spaces. For his show at the Perrotin Gallery in Paris, he was enclosed for 8days and 7nights in a metal sculpture of his body in a seated position, with his head facing a work by Hans Hartung at the end of a cone system placed in front of his eyes which occluded all other visual stimuli. The interior of the metal structure was not padded and there was no head support. His sleep and internal temperature were continuously recorded using polysomnography (Grael, Compumedics) and an orally swallowed temperature sensitive capsule (Bodycap) with temperature sampling every 2min...

Delayed sleep-wake phase disorder (DSWPD) is a circadian rhythm sleep disorder characterised by a delay in the main sleep period, with patients experiencing difficulty getting to sleep and waking up at socially appropriate times. This often causes insomnia and compromised sleep, results in impairment to daytime function and is associated with a range of comorbidities. Besides interventions aimed at ameliorating symptoms, there is good evidence supporting successful phase advancement with bright light therapy or melatonin administration...

Physical exercise differentially increases body temperature according to the time of day, which shows the importance of circadian rhythm in thermal regulation. Given its contribution in central pathways involved in thermoregulation, orexin A could play a role in the regulation of core body temperature during and after exercise. To test this hypothesis, we assessed the effect of exercise, performed at two times of day, on core temperature and on the amount of orexin A in the production zone, i.e., the dorsal hypothalamus...

PURPOSE: TRPV1 desensitization or blockade promotes hyperthermia in rodents. Daily changes in core body temperature (Tc), spontaneous locomotor activity (SLA), and glucocorticoids are temporal cues for peripheral clocks. Thus, this study aimed to evaluate the effects of both desensitization and blockade of TRPV1 on Tc, SLA, blood corticosterone, and the clock genes Per1 and Bmal1 in the liver and adrenal. METHODS AND RESULTS: Resiniferatoxin (RTX, 20 μg kg-1 ) known to desensitize the intra-abdominal TRPV1 channels was i...

It is usually beneficial for species to restrict activity to a particular phase of the 24-hour cycle as this enables the development of morphological and behavioural adaptations to enhance survival under specific biotic and abiotic conditions. Sloth activity patterns are thought to be strongly related to the environmental conditions due to the metabolic consequences of having a low and highly variable core body temperature. Understanding the drivers of sloth activity and their ability to withstand environmental fluctuations is of growing importance for the development of effective conservation measures, particularly when we consider the vulnerability of tropical ecosystems to climate change and the escalating impacts of anthropogenic activities in South and Central America...

Intermittent hypoxia (IH) is a major clinical feature of obstructive sleep apnea (OSA). The mechanisms that become dysregulated after periods of exposure to IH are unclear, particularly in the early stages of disease. The circadian clock governs a wide array of biological functions and is intimately associated with stabilization of hypoxia-inducible factors (HIFs) under hypoxic conditions. In patients, IH occurs during the sleep phase of the 24-hour sleep-wake cycle, potentially affecting their circadian rhythms...

Stroke remains one of the leading causes of mortality and long-term and permanent disability worldwide despite technological innovations and developments in pharmacotherapy. In the last few decades, the growing data have evidenced the role of the circadian system in brain vulnerability to damage, the development and evolution of stroke, and short-term and long-term recovery. On the other hand, the stroke itself can affect the circadian system via direct injury of specific brain structures involved in circadian regulation (i...

Body temperature in homeothermic animals does not remain constant but displays a regular circadian fluctuation within a physiological range (e.g., 35°C-38.5°C in mice), constituting a fundamental systemic signal to harmonize circadian clock-regulated physiology. Here, we find the minimal upstream open reading frame (uORF) encoded by the 5' UTR of the mammalian core clock gene Per2 and reveal its role as a regulatory module for temperature-dependent circadian clock entrainment. A temperature shift within the physiological range does not affect transcription but instead increases translation of Per2 through its minimal uORF...

INTRODUCTION: Sleep-wake and circadian disturbance is a key feature of mood disorders with a potential causal role and particular relevance to young people. Brexpiprazole is a second-generation antipsychotic medication with demonstrated efficacy as an adjunct to antidepressant treatment for major depressive disorder (MDD) in adults, with preliminary evidence suggesting greater effectiveness in subgroups of depressed patients with sleep disturbances. This clinical trial aims to evaluate the relationships between changes in sleep-wake and circadian parameters and changes in depressive symptoms following adjunctive brexpiprazole treatment in young adults with MDD and sleep-wake disturbance...

STUDY OBJECTIVES: Several factors may contribute to the high prevalence of sleep disturbances occurring in postmenopausal women. However, the contribution of the circadian timing system to their sleep disturbances remains unclear. In the present study we aim to understand the impact of circadian factors on changes of sleep and alertness occurring after menopause. METHODS: Eight healthy postmenopausal women and 12 healthy young women in their mid-follicular phase participated in an ultradian sleep-wake cycle procedure (USW)...

BACKGROUND: The circadian clock regulates the function of the immune system, the replication of viruses, and the magnitude of infections. The aim of this study was to analyse whether hospital attendance in Coronavirus disease 2019 (COVID-19) patients presents a diurnal variation. METHODS: Data from the electronic medical records of 1094 COVID-19 patients who presented to a Health Centre in Qatar during the month of July 2020 was retrospectively analysed. The following demographic (i...

AIM: Physiological functions in mammals show circadian oscillations, synchronized by daily cycles of light and temperature. Central and peripheral clocks participate in this regulation. Since the ion channel TRPM8 is a critical cold sensor, we investigated its role in circadian function. METHODS: We used TRPM8 reporter mouse lines and TRPM8-deficient mice. mRNA levels were determined by in situ hybridization or RT-qPCR and protein levels by immunofluorescence. A telemetry system was used to measure core body temperature (Tc)...

Circadian rhythm disturbances are the most common symptoms during the early onset of AD. Circadian rhythm disorders aggravate the deposition of amyloid plaques in the brains of AD patients. Therefore, improving the circadian rhythm of AD patients might slow down the pathological development of neurodegeneration. Circadian regulation is driven by a master clock in suprachiasmatic nuclei (SCN) and peripheral clock located in peripheral organs. The rhythmic feeding-fasting cycle has been proved to dominant cue to entrain peripheral clocks...

Eurycoma longifolia (Tongkat Ali; TA) is a traditional medicinal herb, commonly known as Malaysian ginseng. The root tea has been traditionally applied to treat fevers, aches, sexual dysfunction and other ailments. We evaluated the effects of TA extract supplementation on diurnal core body temperature (BT) and sleep architecture in model mice. Dietary supplementation with TA extract for 4 wk resulted in significantly and moderately reduced BT during the rest and active phases, respectively. A high dose delayed the onset of BT elevation at the start of the active phase, indicating that the effect was dose-dependent...

Snacking of small quantities of palatable food items throughout the day is common in modern societies and is promoted by 24/7 lifestyles. Long-term mistimed high-caloric food intake disrupts endogenous circadian rhythms and supports the development of obesity and other metabolic disorders. However, less is known about the time-of-day dependent effects of snacking. We hypothesized that already a single snacking episode may affect the circadian regulation of metabolic parameters, in particular when the snack is consumed during the daily rest phase...

Mammals maintain their internal body temperature within a physiologically optimal range. This involves the regulation of core body temperature in response to changing environmental temperatures and a natural circadian oscillation of internal temperatures. The preoptic area (POA) of the hypothalamus coordinates body temperature by responding to both external temperature cues and internal brain temperature. Here we describe an autonomous circadian clock system in the murine ventromedial POA (VMPO) in close proximity to cells which express the atypical violet-light sensitive opsin, Opn5...