A driving simulation task: correlations with Multiple Sleep Latency Test.

Sleepiness and driving is a dangerous combination that causes thousands of crashes each year resulting in injury and death. In the last few years, driving simulators have been used to study the performance decrements associated with drowsiness. We correlated performances of a driving simulation task in healthy volunteers in different alertness conditions with objective (MSLT: Multiple Sleep Latency Test) and subjective (SSS: Stanford Sleepiness Scale; VAS: Visual Analogue Scale) sleepiness measurements. The subjects were tested on two days, after a normal night of sleep and after a night of complete sleep deprivation. The study consists of four sessions of MSLT, each one followed by subjective measurements of sleepiness and by a 30 min driving simulation task with a monotonous driving scenario. The parameters that correlate most highly with MSLT are the standard deviation of lane position, the mean RT, crash frequency and exceeding the speed limit frequency. The monotonous driving simulation we adopted showed strong correlations with MSLT and subjective sleepiness scales in healthy subjects and is suitable to evaluate excessive daytime sleepiness in patients.