View clinical trials related to Circadian Rhythm.
Filter by:The goal of the present clinical descriptive study is to characterize and quantify the potential hormonal chronobiological differences between individuals with type 2 diabetes (T2D) and healthy age and weight-matched controls as either circadian aligned or misaligned. The investigators hypothesize that individuals with T2D have a misaligned and different circadian rhythmicity of circadian biomarkers (melatonin and cortisol) than controls, and that this difference in turn is related to 24h hormonal fluctuations, behaviour, and metabolic-, cardiac-, and cognitive parameters. Participants will be asked to: - fill-out a diary on eating and sleeping habits for 30 days - wear an actigraphy and continuous glucose monitor for 10-14 days - stay overnight at the research facility, including continuous blood sampling and polysomnography
This randomized controlled crossover trial of 36 pregnant individuals with gestational diabetes (GDM) or gestational glucose intolerance (GGI) will: 1. Determine the effects of physical activity (PA) timing, specifically 30 minutes of moderate intensity walking or stepping in the morning (between 5am-9am, within 30-40 minutes of starting breakfast), versus late afternoon/evening (between 4pm-8pm, within 30-40 minutes of dinner) on glucose across the 24-hour cycle. 2. Explore the potential effects of the timing of PA on sleep and mood state.
Disruption of circadian rhythms is frequently observed in patients in the intensive care unit (ICU) and is associated with worse clinical outcomes. The ICU environment presents weak and conflicting timing cues to the circadian clock, including continuous enteral nutrition. The goal of this clinical trial is to evaluate the effect of timing of enteral nutrition on the circadian rhythm in critically ill patients. Patients admitted to the intensive care unit will be allocated to receive either continuous or cyclic daytime (8am to 8 pm) enteral feeding. Differences in circadian rhythms will be assessed by 24h patterns in core body temperature, heart rate variability, melatonin and peripheral clock gene expression. Secondary outcomes include depth of sleep, glucose variability and incidence of feeding intolerance. This study is expected to contribute to the optimalisation of circadian rhythms in the ICU.
The goal of this study is to learn more about how the time in which participants consume their meals relative to their personalized circadian rhythm influences their overall cardiometabolic health and weight. The investigators are hoping to discover if a circadian-based time restricted eating intervention will improve cardiometabolic health and decrease weight. The protocol is a 46 day prospective cohort study that includes both field and in-laboratory data collection in overweight and obese individuals.
The study aims to investigate the status of circadian rhythm and sleep quality in ICU patients and their influence factors. And explore the pathway of circadian rhythm on ICU delirium. The hypothesis of study is that icu patients experience circadian and sleep rhythm disorder, especially in patient who have delirium.
Physical exercise is efficacious in controlling blood glucose levels in individuals with Type 2 diabetes. An individual's exercise capacity and ability to utilize glucose as an energy source oscillates throughout the day. Hence, the beneficial effects of exercise on blood glucose levels may depend on the time of day when the exercise bout is performed. However, the time of day in which the most beneficial adaptations to exercise can be achieved remains unknown. This project aims to answer the following questions: Does time of day impact the beneficial effects of exercise on blood glucose? If so, when can the most beneficial effects of exercise be achieved? Which metabolic mechanisms links time of day, exercise and blood glucose control? To address these questions, individuals with or without Type 2 diabetes will perform an exercise session at two different times (09:00 and 16:00), and continuous glucose monitoring will be used to assess the effects of exercise on blood glucose. We will determine the specific metabolic processes which promote the most beneficial blood glucose response. To achieve this, we will measure which metabolic substrates (carbohydrates, lipids and proteins) are used and which metabolites produced in blood, skeletal muscle and adipose tissue in response to exercise at different times of the day.
The Discovery of the circadian clock first established a genetic basis for behavior, and our understanding of circadian rhythm (CIR) has since expanded to provide molecular insights into physiology and disease. Yet the challenge remains to translate these insights regarding the role of the CIR in cells and tissues into the clinic. Many mechanistic pre-clinical experiments have shown that the CIR is directly linked with the Nicotinamide Adenine Dinucleotide (NAD) levels and the NAD redox ratio and that the NAD oscillation amplitude is diminished during aging and in the model of neurological diseases. Human ex-vivo data have also shown that NAD oscillates over time in human red blood cells. While mounting evidence in model organisms illustrate the central role of brain NAD for maintaining energy homeostasis and the CIR, similar data in human are sparse. To date, no study has been reported in human on the effect of the CIR on brain NAD levels. NAD is a vital cofactor involved in brain bioenergetics for metabolism and Adenosine Tri-Phosphate (ATP) production, the energy currency of the brain. NAD exists in an oxidized (NAD+) or reduced (NADH) form, with NAD+/NADH (the redox ratio) being an important determinant of cytosolic and mitochondrial metabolic homeostasis. Additionally, NAD+ is a key substrate for multiple NAD+-dependent enzymes and is consumed by at least four class of enzymes involved in genomic stability, mitochondrial homeostasis, adaptive stress responses, and cell survival, including Sirtuins. Modulation of subcellular NAD+ synthesis can regulate the timing of signaling pathways. Mammalian circadian rhythms are coordinated with metabolic activity through controlled expression of Nicotinamide phosphoribosyltransferase (NAMPT). Regulation of NAMPT, in turn, results in oscillating NAD+ levels. The rhythmic oscillation of NAD+ serves as a feedback 'timer' by modulating the activities of NAD+-dependent enzymes, including sirtuins, helping to establish the periodicity of the cycles. NAMPT oscillations also dictate mitochondrial NAD+ levels and coordinate cellular respiration with awake periods. In these cases, modulation of NAMPT levels drives the rise and fall of NAD+ concentrations that serve to limit the duration of Sirtuins activity. Fine control of neurometabolism is necessary for brain function, because neuronal firing produces dynamic changes in local energy demand. The Astrocyte Neuron Lactate Shuttle Hypothesis (ANLS) provides one way of understanding how these changing needs are met. In this model, neuronal activity increases extracellular glutamate, which stimulates increased glucose uptake and glycolysis in astrocytes. Within astrocytes, lactate is produced from pyruvate in a reversible manner by the lactate dehydrogenase enzyme in the cytoplasm. This enzyme requires NAD as a co-factor and one NADH is converted to NAD+ when one pyruvate molecule is converted to lactate. The astrocytes then release this lactate, increasing its extracellular concentration. Important to the ANLS hypothesis, lactate can be used by nearby neurons as an energy source. Furthermore, under the influence of the CIR regulation, the human psychological and physiological functions fluctuate with time during the day. This effect has been observed in many cognitive domains, as well as in risky decision-making and reward function. The hypothesis is that brain NAD level is modulated by the CIR and that the NAD redox ratio should increase during the day. The primary objective of this project is to determine the brain NAD status in the morning and in the afternoon. Many pre-clinical results have suggested a diurnal effect on brain NAD, yet no clinical data is available. In this study, NAD+ and NADH level of the occipital region will be determined by 31P-MR spectroscopy at 7 T. Total NAD (tNAD) and NAD redox ratio NAD+/NADH will be calculated as well. Measurement will be conducted in the morning in the fasted state (AM session) and in the mid-afternoon (PM session) 3 hours after the lunch intake. To confirm that the AM and PM measurements are done in two different circadian states, salivary cortisol will be measured. Simultaneous detection of other energy metabolites (e.g. lactate, PCr, ATP) will be acquired for exploratory analysis. To explore how the NAD status correlates with behavioral measures of reward activation, the automatic Balloon Analogue Risk Task (BART) test will be performed at the end of each AM and PM session.
Circadian clocks shift later (delay) with the progression of puberty; this shift contributes to late sleep onsets in older adolescents. Early school start times, however, force teenagers to awaken earlier than their spontaneous wake time and the opportunity for sleep shortens. Chronic circadian misalignment and sleep restriction are at their peak during late adolescence, and are associated with various negative outcomes. Morning bright light exposure from light boxes can shift rhythms earlier (phase advance) to facilitate earlier sleep onset, and reduce circadian misalignment and the associated risks. Studies of adults, however, indicate that restricted sleep and exposure to evening light due to late bedtimes make morning bright light less effective in producing advances. Pilot data collected from adolescents mimic this finding, but also suggest that staying awake late in normal household lighting and the subsequent sleep restriction before and during a 3-day morning bright light regimen, can shift the system in the wrong direction (phase delay). The overarching goal of this study is to examine the dose of sleep restriction and evening household light that prevents the desired phase advance to morning bright light in adolescents aged 14-17 years. Study 1 aims to construct a sleep restriction with normal household evening light dose-response curve to determine the point at which morning bright light begins to lose its effectiveness. The investigators hypothesize that the circadian system will advance with sufficient sleep, but with increasing sleep restriction/evening light, circadian rhythms will not shift or will delay despite the phase advancing morning bright light. Study 2 will test whether reducing evening light exposure by wearing sunglasses before bedtime during sleep restriction can facilitate phase advances. The main outcome measures to build the dose-response curve will be phase shifts of the central circadian clock marked by the dim light melatonin onset (DLMO) and total sleep time measured from actigraphy in the laboratory. Secondary outcomes include cognitive performance, sleepiness, and mood.
Chronic circadian misalignment and sleep restriction peak during late adolescence, and are associated with morning daytime sleepiness, poor academic performance, conduct problems, depressed mood, suicidal ideation, substance use, insulin resistance, and obesity. Bright light exposure from light boxes can shift rhythms earlier (phase advance) to facilitate earlier sleep onset and reduce morning circadian misalignment and the associated risks. To phase advance circadian rhythms, the investigators' PRCs showed that the ideal time to begin light exposure was slightly before wake-up time and light should be avoided around bedtime because this is when light produces maximum phase delay shifts. An unexpected finding from these results, however, was a second advancing region in the afternoon (~6 to 9 h after habitual wake-up time) suggesting that afternoon light may have more circadian phase advancing ability than traditionally thought. The overall goal of this mechanistic study is to follow-up on the unexpected PRC findings and test whether individually-timed afternoon light alone and in combination with morning bright light can shift circadian rhythms earlier in older adolescents. Four groups will be compared in a randomized parallel group design: afternoon bright light, morning bright light, morning + afternoon bright light, and a dim room light control. Adolescents will complete a 2-week protocol. After a baseline week with a stable sleep schedule, adolescents will live in the laboratory for 7 days. Sleep/dark and the time of bright light exposure will gradually shift earlier. Bright light (~5000 lux) will be timed individually based on his/her stable baseline sleep schedule. The first 3-h morning bright light exposure will begin 1 h before wake on the first morning. The first 3-h afternoon bright light exposure will begin 5 h after wake. The morning + afternoon exposures will begin at the same times, but each exposure will be 1.5 h so that a total of 3 h of bright light per day will be given to each group except the dim light control group. Phase shifts of the circadian clocks marked by the dim light melatonin onset (DLMO) is the main outcome. Investigators hypothesize that afternoon bright light will work synergistically with morning bright light to produce larger shifts than morning or afternoon bright light alone. These data could challenge the current understanding of how to use bright light to shift circadian rhythms earlier.
The goals of this study are to uncover the influence of diet on the human circadian timing system. The protocol is a 46-day (28 outpatient days, 18 inpatient days over two 9 day visits) randomized cross-over study designed to elucidate the speed of entrainment in response to a high-fat diet.