A driver’s response time in applying the brakes in an emergency is commonly thought to be impaired by sleepiness. Thus, reaction time (RT) given as a task secondary to driving has been seen to be a valid method for monitoring sleepiness, measured by means of the driver pushing a steering-wheel or foot-operated switch in response to stimuli generated within the vehicle. However, driving studies indicate that sleepy drivers will either respond normally to an emergency or not at all; that is, driver response time is disrupted by sleepiness rather than reflecting a gradual decline. Research outside the field of driving has demonstrated that the deterioration in RT performance with sleepiness is reflected in only a portion of responses being impaired. Little is known about what might be expected with RT as a secondary task under less extreme but more typical conditions, such as during the afternoon ‘dip’: following a night of disturbed or restricted sleep. Another issue concerning the application of RT as a secondary task during driving, is that with monotonous roads the very act of responding to the RT stimuli could have an arousing effect, particularly if the stimuli are frequent. With these issues in mind, the authors evaluated the application of simple RT using an auditory stimulus, given with inter-stimulus intervals averaging 2 and a half minutes, within the context of moderate and known levels of sleepiness, and using our standard driving protocol. In these respects they examine whether RT reflects this sleepiness, and/or otherwise affected driving behaviour. (Author/publisher) For the covering abstract see ITRD E116881.
Abstract