Commonly experienced acute and cumulative 8-hour sleep loss differentially affect simulated driving during a...

Sleep loss is a major contributor to traffic accidents, yet the differential effects of two common real-world patterns of sleep loss, acute total sleep deprivation and cumulative sleep restriction producing equivalent 8-hour sleep loss, on vehicle control remain poorly quantified. Leveraging tightly controlled sleep manipulation and highly immersive driving simulation, we directly compared the effects of different patterns of sleep loss under naturalistic driving conditions. Twenty healthy male participants completed a randomized within-subject crossover sleep design, comprising normal sleep, cumulative sleep restriction (four nights 2 h reduced sleep per night), and acute total sleep deprivation (one night without sleep), each followed by a simulated nighttime-to-early-morning commute. Acute total sleep deprivation produced pronounced impairments in vehicle control. Most prominently, lateral control deteriorated within 4-6 min under acute deprivation, with impairments comparable to those reported at high blood alcohol concentrations (1.2-1.4 g/L). Steering instability and integrated driving performance showed convergent deterioration. In contrast, cumulative sleep restriction resulted in smaller and less consistent changes, while vigilance task performance and speed variability were comparatively preserved across all conditions. Despite graded increases in subjective sleepiness across conditions, cumulative sleep restriction produced only limited changes in driving performance, whereas acute sleep deprivation produced a disproportionate risk to driving safety by selectively and rapidly degrading operational vehicle control. These findings, obtained under ecologically relevant sleep and driving conditions, underscore functional and potentially physiological differences between acute and cumulative sleep loss and, practically, highlight the importance of distinguishing between them when considering sleep-loss-related driving impairment and safety risk.