Awareness of sleepiness and ability to predict sleep onset: can drivers avoid falling asleep at the wheel?

Objectives: Regarding the causes of sleep-related accidents, this study assesses whether individuals can anticipate sleep onset accurately and how individuals acknowledge and use physiological and cognitive cues to make judgments related to sleep onset.

Methods: A group of 41 partially sleep-deprived subjects predicted the likelihood of sleep in 30 consecutive two-minute intervals and noted physiological and cognitive signs of sleepiness, including involuntary eye closure, head-nodding, wandering thoughts, yawns, and instances of sleep, collectively referred to as "sleep complaints". Continuous polysomnographic recording compared these predictions to actual instances of sleep.