Many forms of shift work disrupt the normal relation between rest/activity and the circadian regulation of bodily functions (1). Among the most obvious effects of this disruption is disturbed sleep and increased sleepiness (2, 3). Here we will discuss the effects on sleepiness. Much of the data in this area consist of self-ratings but our emphasis will be on some recent approaches that have made use of EEG methods to provide continuous monitoring of fluctuations of sleepiness in freely moving subjects.