Het effect van diepe slaap op het onstaan van obesitas.

Sleep duration and sleep quality are associated with obesity in longitudinal studies. To evaluate what the influence is of the most important stage of the sleep, the slow-wave sleep, on the onset of obesity an intervention is necessary. Therefore, disturbing the slow-wave sleep without waking the subjects and in the meanwhile investigating the endocrinological parameters, energy expenditure,fat oxidation, body temperature, its effect on feelings of reward and feelings of hunger and satiety will give us insight in the etiology of obesity with respect to sleep.

Suppression of SWS, without changing total sleep time, may affect total energy expenditure (TEE), activity induced energy expenditure (AEE), non-exercise activity thermogenesis (NEAT), endocrinological parameters and energy intake.

Subjects spent 2 x 48 hrs in the respiration chamber. Each hour between 07.00 AM and 11.00 PM they have to fill in several questionnaires. Furthermore their urine will be collected every 12 hrs for analysis of nitrogen and palmitic acid.

Subjects will visit the university twice and during each visit they will stay in the respiration chamber for two days and nights (48hrs). During one of these visits subjects will sleep normally; during the other visit SWS will be suppressed. Subjects will be asked for their usual bedtimes during the week. They will be in a partly time-blinded surrounding and told to go to sleep or get out of bed as they are used to. The time, when they switch off the lights, is recorded. Suppresion of SWS sleep will be done with acoustic tones varying in frequency from 500 – 2000 Hz, produced by speakers near the bed. When the EEG records indicate that the subject is in the SWS sleep, two delta waves (?4 Hz, >75 ?V) appearing within 15s, acoustic sounds starting from 40 dB are delivered. If no response occurs, the sound will be increased with 10dB per step till 110 dB maximum. When the maximum tone does not cause any response the subjects name will be spoken over the intercom. Subjects are not supposed to wake up, they only have to skip the SWS sleep. During the day subjects spend their time freely in the chamber, yet are not allowed to sleep.