DIFFERENTIAL UTILITY OF PSYCHOMOTOR VIGILANCE TEST VS. SLEEP LATENCY TESTS IN HEALTHY HUMANS

Abstract Introduction The Psychomotor Vigilance Test (PVT), the Multiple Sleep Latency Test (MSLT), and the Maintenance of Wakefulness Test (MWT) are widely used in both sleep research and clinical settings. The PVT measures reaction time to a visual stimulus, whereas time to sleep onset is measured in both the MSLT and MWT, which differ primarily with respect to the instructions (i.e., whether to try to fall asleep vs. stay awake). Compared to sleep latency tests, the PVT is relatively inexpensive and easy to administer, so it is advisable to delimit the conditions under which its administration is most appropriate. Methods A comprehensive search of sleep studies on healthy adults revealed 30 studies in which both PVTs and sleep latency tests were administered – usually to assess the effects of various interventions on sleepiness and vigilance. Two reviewers compiled findings from each study and graded the levels of outcome agreement based on whether a test intervention produced similar effects on vigilance across tests. Results Of the 13 studies that included both PVT and MWT of studies, a high level of agreement (based on the presence and direction significant effect on vigilance) between test outcomes was evident in 8 (61.5%) of the studies. In contrast, a considerably lower percentage of studies in which both the PVT and MSLT were performed (6 of 17 studies; 35.3%) had high agreement between test outcomes. It was also found that the MSLT was more sensitive to interventions (e.g., caffeine, sleep loss, and cognitive workload) than the PVT in the majority of studies in which there was low agreement (5 of 6 studies; 83.3%). Conclusion There is generally more agreement between PVT and MWT measures than between PVT and MSLT measures in studies involving sleep loss. This is most likely because the PVT and MWT both require application of effort to resist sleepiness, whereas the MSLT involves the withdrawal of resistance to sleepiness. This suggests that the PVT is potentially more useful in operational environments (where ability to sustain performance is the primary concern) than in clinical settings (where the focus is on determining the severity of sleepiness). Support (If Any) Department of Defense Military Operational Medicine Research Program (MOMRP)