De slaap en het bed: een psychobiologische beschouwing

Sleep is a main factor for restoration of body and brain. Two main types of sleep can be distinguished: slow wave sleep, with its deep and light sleep, and REM sleep. Deep slow wave sleep, occurring in the first part of the night, is particularly involved in bodily restoration, while light sleep, in the second half of the night, seems to have a more luxury nature. REM sleep, associated with dreaming, occurs in regular periods during the entire night. The duration of sleep varies commonly between 7 and 8 hours. Sleep begins when body temperature decreases and when the light disappears, while sleep ends when body temperature starts to increase and light returns. The temperature in bed is particularly relevant for sleep and must be in the thermoregulatory zone of 27 to 29 degrees Celsius. In falling asleep a preferable sleeping posture is chosen. Despite this favorite position, there are relatively many movements during the night. This keeps the body in a proper condition during the long period of sleep. Bed, pillow and mattress have to permit these movements and have also to facilitate a side-position of the body. The latter is a better position compared to sleeping on belly or back. In particular snoring occurs the least in a side position. In this way a comfortable bed and good bed materials facilitate sleep, as well as an optimally equipped sleeping room without too much noise, a suitable light-dark regime, an acceptable temperature and proper ventilation and humidity.