The Effects of Total Sleep Deprivation on Neurocognitive Functions

Lee, Heon Jeong; Kim, Leen; Suh, Kwang Yoon

Abstract

OBJECTIVES: The purpose of this study was to investigate the neurocognitive and psycho-physiological effects of total sleep deprivation by using the objective and quantifiable methods of Vienna Test System (Reaction Unit, Cognitrone, Vigilance) and P300 event-related potential.
METHODS
Thirty healthy medical students(22 men, 8 women) participated in this study. Subjects remained awake for 38 hours under continuous surveillance. In the morning and the evening of two consecutive study days, the Vienna tests and P300 were performed.
RESULTS
In Vigilance test of the Vienna Test System, a significant functional impairment occurred as a result of total sleep deprivation(p<.001). In Reaction unit, reaction time significantly increased (p<.01). However, in Cognitrone, a functional improvement was revealed. The P300 latency was significantly prolonged(p<.001) and amplitudes decreased(p<.01) as a consequence of total sleep deprivation. Comparing the results of Vigilance and Reaction unit each taken in the morning and evening, the performance decrements were prominent in morning sessions. In Cognitrone, evening session result showed the improvemed performance.
CONCLUSIONS
The cognitive impairment resulting from 38 hours of sleep deprivation are considerable in alertness and reaction time tests, but not in higher complex cognitive functions such as fine perceptual analyses, visual discrimination, and short term memory. Considering the results with P300 latency and amplitudes, it may be concluded that the P300 changes as a result of total sleep deprivation are due to the decrement in the alertness which prolongs reaction time. More deterioration of cognitive performance shown in the morning, could be explained by considering circadian rhythm.