Effects of acute or cumulative 8-hour sleep loss on simulated driving in a naturalistic, monotonous night-time setting: a randomized, controlled, crossover trial

Sleep loss is a major contributor to traffic accidents, yet the differential effects of acute versus cumulative 8-hour sleep loss on vehicle control remain poorly quantified. This study leveraged tightly controlled sleep manipulation together with highly immersive driving simulation to directly compare sleep-loss modes under naturalistic driving conditions. To evaluate subjective sleepiness, driving performance and vigilance, healthy male participants completed a randomized within-subject crossover sleep design, comprising normal sleep, cumulative sleep restriction (four nights with 2 h reduced sleep per night), and acute total sleep deprivation (one night without sleep), each followed by a simulated nighttime-to-early-morning driving protocol segmented into modules. Linear mixed-effects models evaluated condition effects and time-on-task dynamics. Acute total sleep deprivation produced pronounced impairments in vehicle control. Most prominently, lateral control deteriorated rapidly under acute deprivation, with effect magnitudes comparable to those reported at high blood alcohol concentrations. 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 increased subjective sleepiness, cumulative sleep loss provoked relatively small 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 underlying 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. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=109 SRC="FIGDIR/small/26343648v1_ufig1.gif" ALT="Figure 1"> View larger version (49K): org.highwire.dtl.DTLVardef@194a7ecorg.highwire.dtl.DTLVardef@9c8620org.highwire.dtl.DTLVardef@29a451org.highwire.dtl.DTLVardef@1e2d777_HPS_FORMAT_FIGEXP M_FIG C_FIG Clinical Trials - name, URL and registrationO_ST_ABSClinical Trial nameC_ST_ABSStudy of Identification of Metabolomics-based Sleepiness Markers for Risk Prevention and Traffic Safety - ClinicalTrials.gov Identifier NCT05585515, released on 18.10.2022, https://clinicaltrials.gov/study/NCT05585515; Swiss National Clinical Trial Portal SNCTP000005089, registered on 12.08.2022, https://www.humanforschung-schweiz.ch/de/studiensuche/studien-detail/58930 IRB StatementThis study was approved by the local ethics committee (Kantonale Ethikkommission Zurich, reference number 2022-01273). No identifying images or other personal or clinical details of participants are presented here or will be presented in reports of the trial results. Informed consent materials are available from the corresponding author on request. We confirm all methods were performed in accordance to the Declaration of Helsinki and its later amendments. Statement of significanceSleep loss is common, but not all forms of sleep loss affect driving in the same way. This study shows that a single night without sleep and several nights of restricted sleep have fundamentally different consequences for vehicle control, despite producing significant feelings of sleepiness. By combining controlled sleep manipulation with immersive, ecologically relevant driving assessment, the work reveals that acute sleep deprivation uniquely disrupts the ability to maintain stable control of a vehicle, whereas cumulative sleep loss produces more limited performance changes. These findings challenge assumptions based solely on subjective sleepiness and highlight the need to distinguish between sleep-loss patterns when evaluating driving safety. Future work should address how drivers recognize and respond to these distinct forms of impairment.