[Effect of stress on sleep characteristics in humans]

Earlier investigations of Baekeland et al. (1968) showed that stress conditions change the characteristic features of sleep. It was the aim of this work to compare the effect of pre-examination stress and preoperative stress on the characteristic features of sleep. Three groups of 5 individuals each were studied: students, patients and controls aged from 20 to 45 years. In all patients psychological investigations by the test of Cattel were carried out before each polygraphic recording. These investigations confirmed presence of anxiety prior to falling asleep in the groups of students and patients and its effect on the subsequent sleep. The most significant changes during stress were observed in paradoxical sleep (REM). The amount of this sleep is reduced during stress while its intensity increases significantly (phasic REM sleep period). Persistence of disturbances of sleep depends on the duration of stress stimulus. The stress reaction connected with examination was short-lasting and disappeared after passing the examination. In the group of patients the stress reaction was prolonged on the average 33 days after the operation.