Effect of Sleep Debt on Neurophysiological Responses to Heat Exposure

Study Overview
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Brief Summary
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Many people are required to work in stressful situations combining sleep debt and hot environmental conditions. If the effect of sleep debt on cognitive performance is proven, this effect could be increased, during heat exposure, through the deleterious effects of sleep debt on thermoregulatory abilities. These alterations may favour the occurrence of accidents. The changes in cognitive performance induced by hyperthermia are also poorly characterised and often not dissociated from the effects of dehydration. Little is known about the effects of the combination of sleep debt and heat exposure on mental performance. Describing and understanding the alterations induced by this combined situation could provide a better understanding of the mechanisms explaining the deterioration of performance in hot conditions and promote the development of appropriate countermeasures.

Official Title
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Effect of Sleep Debt on Neurophysiological Responses to Heat Exposure

Conditions
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Heat; Excess, Sleep Disorder

Intervention / Treatment
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* Other: Sleep recording (at home)
* Other: Heat exposure
* Other: Normal sleep
* Other: Sleep restriction


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: 18 to 35 years old Body Mass Index between 18 and 27 kg/m2 Body weight ≥ 54 kg Exclusion Criteria: Presence or history of medical pathology (cardiological, renal, hepatic, cutaneous, intestinal, neurological...) Presence of a significant deviation from the normal values observed on the electrocardiogram History of heat stroke Known intolerance to heat (e.g. migraine sufferers) Presence of a contraindication to blood sampling, notably low venous capital, belonephobia Inability to ingest a capsule or refusal of the rectal probe Habitual consumption of caffeine > 500 mg per day Alcohol consumption greater than the equivalent of 3 glasses of wine per week Consumption of narcotics Smoking > 0.5 packet of cigarettes per day Undergoing habitual medication Pregnant or breastfeeding woman

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 35 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Normal sleep first<br>The night before the first heat exposure, the participants will have a normal night at home. The night before the second heat exposure, the participants sleep will be restricted to 3 hours in bed. | Other: Sleep recording (at home)<br>* Before both heat exposures, the sleep-wake rhythm will be measured at home for 7 days using actigraphy and a sleep diary that will have been given to him/her during the inclusion visit.<br>Other: Heat exposure<br>* The subjects will be exposed twice (2 different visits) to heat (45°C; 60-70% humidity rate) for 3 hours in a climate chamber. The subjects will be equipped with various external sensors allowing the continuous recording of core temperature, mean skin temperature (9 skin measurement points), heart rate, cerebral electrical activity, cerebral oxygenation, skin vascular conductance (blood flow by laser-doppler), blood pressure and skin conductance. Neurophysiological and cognitive exploration (NPCE) includes the Stroop test, the Psychomotor Vigilance Task (PVT) and the odd-ball test.<br>Other: Normal sleep<br>* The night before one of the two heat exposures (first visit for the Normal sleep first group and second visit for the Reduced sleep first group), the participants will have a normal night at home. The duration and quality of sleep will be measured using a connected headband (Dreem®) allowing for polysomnography.<br>Other: Sleep restriction<br>* The night before one of the two heat exposures (first visit for the Reduced sleep first group and second visit for the Normal sleep first group), the participants' sleep will be restricted. The sleep restriction will correspond to a reduced sleep period with a bedtime of 3 hours (04:00 - 07:00). This night of sleep restriction will be carried out in a sleep apartment (at the lab). The duration and quality of sleep will be measured using a connected headband (Dreem®) allowing for polysomnography.<br>|
| Reduced sleep first<br>The night before the first heat exposure, the participants sleep will be restricted to 3 hours in bed. The night before the second heat exposure, the participants will have a normal night at home. | Other: Sleep recording (at home)<br>* Before both heat exposures, the sleep-wake rhythm will be measured at home for 7 days using actigraphy and a sleep diary that will have been given to him/her during the inclusion visit.<br>Other: Heat exposure<br>* The subjects will be exposed twice (2 different visits) to heat (45°C; 60-70% humidity rate) for 3 hours in a climate chamber. The subjects will be equipped with various external sensors allowing the continuous recording of core temperature, mean skin temperature (9 skin measurement points), heart rate, cerebral electrical activity, cerebral oxygenation, skin vascular conductance (blood flow by laser-doppler), blood pressure and skin conductance. Neurophysiological and cognitive exploration (NPCE) includes the Stroop test, the Psychomotor Vigilance Task (PVT) and the odd-ball test.<br>Other: Normal sleep<br>* The night before one of the two heat exposures (first visit for the Normal sleep first group and second visit for the Reduced sleep first group), the participants will have a normal night at home. The duration and quality of sleep will be measured using a connected headband (Dreem®) allowing for polysomnography.<br>Other: Sleep restriction<br>* The night before one of the two heat exposures (first visit for the Reduced sleep first group and second visit for the Normal sleep first group), the participants' sleep will be restricted. The sleep restriction will correspond to a reduced sleep period with a bedtime of 3 hours (04:00 - 07:00). This night of sleep restriction will be carried out in a sleep apartment (at the lab). The duration and quality of sleep will be measured using a connected headband (Dreem®) allowing for polysomnography.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Number of errors at the Stroop test | Written color names that differ from the color ink they are printed on will be displayed on a computer screen. In the first trial, the participant must say the written word. In the second trial, the participant must name the ink color instead. The higher the number of correct answers, the higher the score. | Through study completion (25 months) |