CHANGES IN DIRECT-CURRENT POTENTIALS DURING SLEEP-DEPRIVATION

Previous research reported changes in steady-state brain electrical ac tivity during sleep. However, due to the quasi-linear nature of the Di rect Current (DC) changes, artifact contamination was a potential conf ound. The present study was performed to further explore DC potentials and to help establish its validity. Twenty-five male university stude nts (13 control and 12 sleep-deprived; mean age 19 y (range 17-27 y) s erved as subjects. During wakefulness, subjects were tested every hour while standard EEG activity recordings were made, as well as DC measu rement. Split plot analyses of variance (ANOVAs) revealed that changes in DC activity levels differed between the two groups. The control su bjects showed the same pattern of decreasing DC observed previously wi th a return to baseline levels during waking hours. The sleep-deprived subjects showed a smaller decrease in DC level through the night, fol lowed by a rise in DC level that continued until the end of the 24 h s tudy. It was concluded that DC measurement reflects changes in brain s tate associated with fatigue that are not attributable to artifactual processes.