Decision-making After Sleep Restriction

Study Overview
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Brief Summary
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The aim of this project is to investigate whether enhancing sleep intensity locally in the prefrontal cortex (PFC) can counteract a deterioration of cognitive control and therefore the previously described increase in risk seeking during chronic sleep restriction. To this end, a controlled, counter-balanced study, consisting of two weeks of sleep restriction will be performed. During one of the sleep restriction weeks, sleep intensity in the PFC will be non-invasively enhanced by acoustic stimulation of slow waves during sleep.

Official Title
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Linking the Change in Decision-making After Sleep Restriction to the Restorative Function of Sleep

Conditions
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Sleep Restriction

Intervention / Treatment
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* Behavioral: Sleep restriction
* Other: Acoustic stimulation


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Age between 18-21 years or 26-30 years, Right-handedness, Good general health, Good understanding of German language (as all information is provided in German) Signed Informed Consent after being informed. Exclusion Criteria: Contraindications on ethical grounds, Clinically significant concomitant disease states (e.g., renal failure, hepatic dysfunction, cardiovascular disease, etc), Known or suspected non-compliance, drug or alcohol abuse (> 5dl wine/ >1l beer daily), Regular medication intake, Enrolment into a clinical trial within last 4 weeks, Diseases or lesions of the nervous system (acute or residual included neurological and psychiatric diseases), Sleep disorders (e.g. Insomnia, sleep apnoea, restless leg syndrome, narcolepsy, etc.), Sleep complaints in general or excessive daytime sleepiness (Pittsburgh Sleep Quality Index > 5; Epworth Sleepiness Scale ≥ 11), Irregular sleep-wake rhythm (e.g. shift working), Long (> 10 hours per night) or short sleepers (< 7 hours per night), Sleep efficiency < 80% in screening night, Travelling with time lag less than 1 month ago (or planning to do so within 1 month prior to or during the study), > 5 drinks or food items containing caffeine per day, > 5 cigarettes per day, Body Mass Index < 19 or > 30 kg/m2, Skin allergy or very sensitive skin Student of one of the following subjects: Mathematics, Physics, Computer Science, Economics, or Psychology (since students of these subjects have profound knowledge of probability calculations, which could interfere with our measurements in decision-making). Red-Green Colour-Blindness (as the Risk Task requires the distinction between red and green), History of claustrophobia, Known hearing disorder (as acoustic stimuli will be applied during sleep), Magnetic Resonance (MR) contraindication (such as pacemaker, implanted pumps, shrapnel, etc.; full MR Screening form will be filled out).

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 30 Years

Sexes Eligible for Study
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Male

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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Design Details

Primary Purpose: Basic Science
Allocation: Randomized
Intervention Model: Crossover Assignment
Masking: Triple


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Sham Comparator: Sleep restriction without acoustic stimulation<br> | Behavioral: Sleep restriction<br>* Time in bed will be restricted to 5 hours per night for 7 nights.<br>|
| Experimental: Sleep restriction with acoustic stimulation<br> | Behavioral: Sleep restriction<br>* Time in bed will be restricted to 5 hours per night for 7 nights.<br>Other: Acoustic stimulation<br>* Brief tones will be presented time-locked to ongoing slow waves during deep sleep.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| risk-premium | risk-preference (i.e. risk premium assessed with the risk Task as described in Maric et al. 2017 Ann Neurol) after chronic sleep restriction with and without acoustic Stimulation will be quantified by the risk-premium derived from the choices made in the risk-task as described in Maric et al. 2017 Ann Neurol. | comparison of change from baseline after 7 nights of sleep restriction with acoustic stimulation to change from baseline after 7 nights of sleep restriction without acoustic stimulation | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| high-density electroencephalography (hdEEG) marker of sleep pressure | Slow wave activity (SWA) assessed by hd-EEG with 128 electrodes | assessed during first and last sleep restriction nights in comparison to baseline values | 
| brain metabolites | Glutamate and gamma-aminobutyric acid (GABA) concentration in the right prefrontal Cortex assessed by magnetic resonance (MR) spectroscopy | before to after 7 nights of sleep restriction with and without acoustic stimulation | 
| vigilance measures | Performance impairments in the psychomotor-vigilance task | before to after 7 nights of sleep restriction with and without acoustic stimulation | 
| deception willingness | deception willingness measured by the willingness to deception of outcome in a card game with binary outcome (win and loss) | before to after 7 nights of sleep restriction with and without acoustic stimulation | 
| Motor inhibitory control performance | inhibitory control performance measured by the stop-signal-task. | before to after 7 nights of sleep restriction with and without acoustic stimulation | 
| confidence | overconfidence measured by an incentivised procedure that elicits the certainity equivalent of a bet based on Performance in a quiz (cf. Murad et al. 2016 J Risk Uncertain) | before to after 7 nights of sleep restriction with and without acoustic stimulation | 
| overconfidence | overconfidence measured by an incentivised procedure that elicits the certainity equivalent of a bet based on Performance in a quiz (cf. Murad et al. 2016 J Risk Uncertain) | before to after 7 nights of sleep restriction with and without acoustic stimulation | 
| impulsivity | impulsivity as measured by an intertemporal choice Task. | before to after 7 nights of sleep restriction with and without acoustic stimulation | 
| Ocular inhibitory control performance | Ocular inhibitory control Performance measured by the Anti-Saccade Task. | before to after 7 nights of sleep restriction with and without acoustic stimulation | 
| Effort in inhibitory control performance | Pupil response (i.e. dilation) during a simple Go/No-Go Task. | before to after 7 nights of sleep restriction with and without acoustic stimulation | 
| Excessive daytime sleepiness | Excessive daytime sleepiness assessed by the Epworth sleepiness scale and the Stanford Sleepiness Scale. | before to after 7 nights of sleep restriction with and without acoustic stimulation |