To understand better the pathophysiological aspects of disturbed sleep, six healthy male students underwent a series of sleep recordings. On the experimental night, subjects' sleep was disturbed, and the effects on contingent negative variation (CNV) were studied. Mean CNV amplitude decreased in magnitude in the Fz as well as Cz areas; the decrease in Fz-CNV tended to be greater in those subjects whose sleep was most disturbed. The decrease in amplitude of CNV appears to be a nonspecific phenomenon that occurs after any kind of disturbed sleep. Contingent negative variation is composed of two or more components with different spatiotemporal distribution. Depending on the placement of electrodes, the effect that disturbed sleep has on CNV will or will not be observed. The decreases in CNV amplitude were noted in the Fz and Cz areas. Other than subjective discomforts, psychometric measurements did not change significantly. Our data indicate, from the topographical and constructional analysis of CNVs, the possible involvement of the frontal lobe function after disturbed sleep.