The objective of this study is to compare the impact of extended wakefulness (i.e., sleepiness) and prolonged driving (i.e., fatigue) at the wheel in simulated versus real-life driving conditions. Participants drove on an INRETS-MSIS SIM2 simulator in a research laboratory or an open French highway during 3 nocturnal driving sessions. A dose-response design of duration of nocturnal driving was used: a 2áh short driving session (3-5 AM), a 4áh intermediate driving session (1-5 AM) and an 8áh long driving session (9 PM-5 AM). Participants were two groups of healthy male drivers (20 for simulated driving and 14 drivers for real driving; mean ageá_áSDá=á22.3á_á1.6 years), free of sleep disorders. The number of inappropriate line crossings, self-rated fatigue and sleepiness were recorded in the last hour of driving sessions to control the effects of prior waking time and time of day. Compared to the daytime reference session, both simulated and real driving performance were affected by a short nocturnal driving session (Pá<á.05 and Pá<á.001, respectively). Extension of nocturnal driving duration affected simulated performance nonlinearly and more severely than that of real driving (Pá<á.001). Compared to the daytime reference session, short nocturnal simulated and real driving sessions increased self-perceived fatigue and sleepiness. Real and simulated driving conditions had an identical impact on fatigue and sleepiness during extended periods of nocturnal driving. In healthy subjects, the INRETS-MSIS SIM2 simulator appropriately measures driving impairment in terms of inappropriate line crossings related to extended wakefulness but has limitations to measure the impact of extended driving on driversÆ performance. (A) Reprinted with permission from Elsevier.
Abstract