Driving Simulation Performance and EEG Evaluation Associated with Obstructive Sleep Apnea

Sleepiness and driving are a dangerous combination that causes thousands of crashes each year resulting in injury and death. This problem not only jeopardizes the safety of the driver but passengers and other drivers as well. This study investigated driving performance and neurophysiological correlates of sleepiness during driving simulation in obstructive sleep apnea patients. The study included 15 obstructive sleep apnea patients and 15 normal subjects as a control group. After a practice drive through city conditions, participants completed a 60 minute driving simulation task designed to replicate a highway driving scenario. Driving performance and EEG data were continuously sampled for the duration of the task and grouped in six 10 minute blocks. Performance measures included lane position and speed variability, in addition to crash frequency data. EEG measures included the frequency and duration of microsleep activity. Subjective measures included sleepiness ratings pre-simulation and post-simulation using a Visual Analog Scale. A repeated measures design analyzed performance, EEG, and subjective measures between groups and across time. The performance results demonstrated that apnea patients had increased lane position variability and a higher number of crashes compared to the control group and across time. Apnea patients also showed increased speed variability compared to the control group, but not across time. The EEG results demonstrated that apnea patients had increased microsleep frequency and duration compared to the control group and across time. The VAS data showed higher levels of sleepiness reported by apnea patients compared to controls. It also showed higher levels of sleepiness post-simulation scores compared to pre-simulation scores. There was no significant interaction for the VAS that suggests apnea patients are unable to recognize their sleepiness and impaired performance. The excessive daytime sleepiness caused by the sleep disorder resulted in microsleep activity and degraded performance which was unmasked by the vigilant nature of highway driving. This study demonstrates the legitimate concern for highway safety among the sleep disordered population, the need for fatigue countermeasures, and highway safety education programs.