INTRODUCTION:Although a number of studies have examined the effects of sleep deprivation on performance, the results are not easily explained. The purpose of the current study was to examine the effects of sustained operations and acute sleep deprivation on tasks that require a wide range of information processing. The current study also provided preliminary data on the use of the controlled attention model to better understand the effects of sleep deprivation. METHODS:There were 24 college students who were paid to remain awake for one night and complete a variety of cognitive and vigilance tasks. Each task was administered four times during the night, once in each testing session (17:30-21:30, 21:45-01:45, 02:30-06:30, and 06:45-10:45). All tasks were counterbalanced across the testing sessions. RESULTS:The data were converted to z-scores and repeated-measures ANOVAs were completed. Performance did not significantly decrease on the more complex cognitive tasks over the night of sleep deprivation. Performance on the vigilance tasks decreased significantly across the night. CONCLUSIONS:Examining the characteristics of the cognitive tasks indicated that although they required different types of processing, they encouraged the participants to remain attentive to and engaged in the task. In contrast, the vigilance tasks were less intrinsically interesting and engaging. Thus, it seems likely that the participants were less capable of maintaining attention on the vigilance tasks than the cognitive tasks. These results indicate that a controlled attention model may be useful in better understanding the effects of sustained operations and sleep deprivation on performance.