Impaired wakefulness in machine operators poses a danger not only to themselves but often to the public at large as well. 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 continuous vigilance monitoring using electroencephalography (EEG) and reaction time measured as the latency of the probanďs reaction to sound stimulus. If constructed, the set together with other logical elements and an alarm systém can be used for an autornatic detection of vigilance and, possibly, also of arousal stimuli in cases of micro-sleep.