consequences of caffeine intake in sleep restricted teenagers

Conditions: Caffeine; Insufficient Sleep

Summary: the goal of this clinical trial is to systematically investigate two prominent factors in teenagers' daily life: caffeine and sleep restriction (sr) and their combined influence on sleep, cognition, and behavior in healthy adolescents. the main questions it aims to answer are: the effects of caffeine under conditions of sr and se: * on sleep pressure and sleep continuity. * on bold activity differences in reward related areas during a reward task (monetary incentive delay task) and on reaction times (behavioral aspect) in the same task. * on bold activity differences during a risk taking task (wheel of fortune task) and on risky decision-making (behavioral aspect) in the same task. participants will be either in the sr or se condition (between-subject). the protocol consists of 2x of approximately one week in which a participant will receive caffeine or placebo (within-subject) at the last two evenings. the experiment consists of an ambulatory and a laboratory phase: * the ambulatory phase consists of 5 nights, including 3 stabilization nights (8h sleep opportunity) prior to 2 nights consisting of either sr with 6h sleep opportunity or se with 9.5h sleep opportunity. participants will wear an actiwatch and fill out sleep diaries during this period. * the laboratory phase will be the 6th evening, night and morning of the protocol and will be spent in our lab. participants will do the following: * treatment (caffeine vs. placebo) intake * saliva sampling * drug screening * cognitive tests, including risk-taking and reward task * filling in questionnaires (sleep diary, sleep quality, sleepiness, mood, expectancy) * waking and sleep with eeg the next day, participants will undergo an fmri scan, including the following: * resting-state scan * structural scan * arterial spin labeling scan * reward task scan * risk-taking task scan around the scan, participants will fill out/undergo: * saliva sampling * questionnaires (reward task, mood, sleepiness, expectancy)


Eligibility criteria:
inclusion criteria: * age ≥ 14 and ≤ 17 * clinically healthy * signed consent form of participant and legal guardian exclusion criteria: * inability to operate tasks or understand the study information * participation in other clinical trials \<3 months prior to any possible study start date * bmi p3 \< bmi-pc \< p97 * any general health concerns or disorders (previous diagnosis of heart/cardiovascular/nephrological/endocrinological/diabetic/metabolic/chronobiologic/ psychiatric/neurological \[particularly epilepsy and parasomnia\] conditions) which may make participants vulnerable to potential negative effects of sr or caffeine or which may affect outcome measures * unavailability to complete the two study protocol weeks within a three-month period * trans meridian travel (\>2 time zones) \<1 month before any possible study start date * shift work \<3 months prior to any possible study start date * extreme chronotype msfsc \ 6:00 according to mctq * subjective sleep duration on school days \ 9h according to mctq * metallic prosthesis, metallic implants, or non-removable objects in the body (e.g., splinters, piercings) which affect mri safety * tattoos with larger diameter than 10cm or above shoulder area, affecting mri safety * claustrophobia * difficulties or problems in physical well-being and mental health based on the swiss norm (t\< 35) for all genders aged 12-18 according to kidscreen-27 * daily nicotine use * use of medications or drugs that have contraindications and/or effects on outcome measures or use of specific drugs indicated in drug test * use of alcohol to an extent that it is likely to have contraindications and/or effects on outcome measures * any indication of previous withdrawal or oversensitivity to caffeine * sleep quality \>5 according to psqi * problems of eeg compatibility * sleep efficiency \<70% * identification of sleep disorders * pregnancy * deviation from the stabilisation sleep-wake schedule by +-60 mins * deviation from protocol sleep-wake schedule by +-30 mins

Keywords: adolescence sleep caffeine risk-taking reward