an alarm system for signaling incapacity of a vehicle driver to sustain a safe level of attention to his driving as may be occasioned by want of sleep or the influence of alcohol or drugs , with such system including an electric enabling switch in series with the ignition switch and the battery . a normally closed push button alarm switch is mounted on the steering wheel whereby a driver &# 39 ; s hand can concurrently grip the steering wheel and depress the button to keep the alarm switch open . the alarm switch is in series with the other switches as well as with an alarm signaling device so that an alarm is given when the driver &# 39 ; s grip on the steering wheel is relaxed . another signal device is connected in series with the battery and the ignition and enabling switches whereby passengers may be assured that the alarm system is energized and has not been disabled by an overconfident driver .