Variation of Driver's Arousal Level During Car Driving in Japan

The 104,635 cases of rearward collisions that occurred in 1974 accounted for 21% of all traffic accidents, the largest single category of accidents. It is thought that many of these accidents were caused by insufficient driver alertness due to a drop in the level of awareness or responsiveness.

Using 18 male subjects, aged from 22 to 29, we conducted a test of reduction in the level of consciousness as determined by continuous measurements during normal driving of EEG, ECG and EOG. Six of the subjects showed a drop in consciousness as indicated by the appearance of an alpha (α) wave of 8-13 Hz. Such waves appeared most frequently following the noontime meal. It can be postulated that their origin is a temporary state of psychological relaxation produced by a number of factors including mental fatigue, drop in the will to drive caused by phenomena of familiarity and daily bodily rhythms. It can be concluded that drivers must pay special attention to preventing the buildup of fatique; at the same time, particular care must be taken after ingestion of meals.