Mild acute sleep restriction alters visual attention during driving: an eye-tracking study using a driving simulator

OBJECTIVES: Safe driving requires cognitive resources such as attention, working memory, and decision-making. Sleep loss impacts these resources, affecting driving performance. Although severe or chronic sleep deprivation is well-studied, the impact of the far more common, mild and acute sleep loss remains less well understood. Similarly, current eye tracking technology in passenger vehicles relies on eye closures or head position as a marker of drowsiness. But these are downstream indicators of fitness to drive. Eye fixation patterns may be a more sensitive, early warning sign of drowsiness. Eye movements were studied to identify patterns (i.e., fixations) reflecting reduced cognitive and behavioral performance during a driving simulation, related to mild sleep loss from the previous night. It was hypothesized that even a single night of reduced sleep would reduce vigilance and impair driving performance, with oculomotor features serving as physiological markers of these deficits. METHODS: Twenty-two participants completed 1-h driving simulations requiring sustained attention and quick responses under two conditions: while normally rested, or after mild sleep restriction. RESULTS: Sleep restriction led to slower response times, increased lapses and crashes, and altered eye fixation patterns across different driving demands (e.g., tailgating or not) that reflect cognitive processing of the environment. CONCLUSIONS: These findings suggest that eye fixations may be useful indicators of driver fatigue and reduced driving fitness related to mild acute sleep loss. These results provide insight into the underlying cognitive processes that may be associated with sleep loss-related fitness to drive.