VARIATION OF BRAIN-STEM AUDITORY-EVOKED POTENTIALS DURING ALL-NIGHT SLEEP INVESTIGATIONS

Continuous monitoring of brainstem auditory evoked potentials (BAEPs) was performed simultaneously with polysomnographic recording during nocturnal sleep in ten normal male subjects (mean age: 25,1 +/- 2,8 years). Four channels of electroencephalogram, respiration (abdominal and thoracic), rectal temperature, electrocardiogram, electrooculogram, chin electromyogram, and two channels of BAEPs were sampled by a multivariable monitoring PC system and stored on an optical disk. All data except BAEPs were preprocessed, integrated over thirty seconds and printed on a single sheet. Sleep stage classification was done visually. BAEPs were analysed in the awake state and in different sleep stages. The results showed no significant changes in absolute latencies and interpeaklatencies I-III, III-V and I-V in correlation with different sleep stages. Insignificant BAEP alterations were found to be related to physiological temperature variations during the night. These changes showed an increase in latencies in connection with a decrease in body temperature.