EEG frequency and finger pulse volume as predictors of reaction time during sleep loss

Abstract

The validity of EEG frequency and finger pulse volume for predicting reaction time increased as sleep loss increased. In general, the EEG showed the highest correlation with reaction time, especially in the 1 sec interval just before and just after the signal. As sleep loss increased, the “lead time” for the EEG increased so that by 50 h of sleep loss, valid predictions of reaction time could be made at least 2–3 sec before the signal. Five out of seven subjects showed a bimodal EEG frequency distribution during sleep loss. For these five subjects, perceptual-motor lapses occurred during periods in which the EEG frequency was in the theta rhythm (4–7 c/sec) range. For two of the subjects whose modal EEG frequency slowed somewhat, but did not have a secondary mode at 4–7 c/sec, neither the EEG nor finger pulse volume could be used to predict reaction time. Finger vasodilation was significantly related to long reaction times during sleep loss, but its contribution to the prediction of reaction time was small.