Driver Fatigue: Is Something Missing?

Drowsiness and fatigue are serious problems in all transportation systems. One persistent issue is the lack of an agreed definition of these respective energetic states. Here we review the theoretical approaches (cognitive versus physiological) framing the driver fatigue problem. Known contributing factors to drowsiness include sleep debt, circadian rhythm, and shift work. However, we also suggest that certain inherent physiological reactions engaged in responses to motion itself represent a previously unrecognized but significant source of fatigue. We confirm the impact of this factor through comparisons of studies that either have or have not included prolonged motion