Relationship between Sleepiness Symptoms Questionnaire Ratings and Psychomotor Vigilance Test Performance in a Laboratory-Based Sleep Deprivation Study

Primary author: Alicja Skwara
Co-author(s): Lillian Skeiky; Hans Van Dongen; Devon Hansen

Primary college/unit: Elson S. Floyd College of Medicine
Campus: Spokane


Sleep deprivation has been demonstrated to adversely impact on cognitive performance and safety. Measuring the impairment caused by sleep deprivation is best done with objective performance assessments such as the psychomotor vigilance test (PVT), but subjective self-report assessments may provide a more practical alternative in real-world settings. The Sleepiness Symptoms Questionnaire (SSQ) is a self-report instrument based on ratings of observable symptoms of sleepiness and motor vehicle driving performance impairment. In a laboratory-based sleep deprivation study, we compared SSQ ratings to performance impairment on a 10min PVT.
Twelve healthy normal sleepers (ages 21-39y, 6 females) participated in a 4-day in-laboratory study. Between a baseline day and a recovery day, participants underwent 38 hours of total sleep deprivation. Participants completed the SSQ and PVT following 6.5, 14.5, 22.5, and 30.5 hours of sleep deprivation, and 6.5 hours after recovery sleep.
As sleep deprivation progressed, the SSQ sleepiness ratings and the number of lapses (reaction times > 500 ms) on the PVT were elevated, peaking after 22.5 hours awake. Both measures returned to baseline levels after recovery sleep. There was a moderate correlation between SSQ ratings and PVT lapses (r=0.44, F1,43=24.1, p<0.001). Subjective sleepiness on the SSQ and objective performance impairment on the PVT reflected expected changes by time awake and time of day during sleep deprivation and following recovery sleep. The moderate correlation we observed suggests that the SSQ may be reasonably reliable for measuring impairment under conditions of acute sleep deprivation.