Impaired wakefulness in machine operators poses a danger not only
to themselves but often also to the public at large. While on duty, such persons are expected to be continuously, i.e., without interruption, on the alert. For that purpose, we designed and carried out an experimental model of continuons vigilance monitoring using electroencephalography (EEG) and reaction time measured as the latency of the probanďs reaction to sound. If constructed, the set together with other logical elements and an alarm can make for an automatic detection of vigilance and, possibly, also of arousal stimuli in cases of microsleep. We have found the following new facts and coníirmed the validity of some of the earlier ones.