Awareness of sleepiness when driving.

The extent to which sleepy drivers are aware of sleepiness has implications for the prevention of sleep-related crashes, especially for drivers younger than 30 years old who are most at risk. Using a real car interactive simulator, we report on EEG, subjective sleepiness, and lane drifting (sleepiness-related driving impairment) from 38 sleep-restricted, healthy young adults undergoing nontreatment control conditions from three (unpublished) investigations using the same experimental protocols for assessing various drinks intended to alleviate sleepiness. Participants drove 2 h during midafternoon under monotonous conditions. For all studies, subjective sleepiness and EEG activity indicative of sleepiness were highly correlated, with both changing concomitantly, along with lane drifting. Drivers had knowledge of their physiological sleepiness. There were indications that sugar content of these drinks may additionally affect sleepiness.