Study objectives: To measure simulated driving performance in obstructive sleep apnea patients and its relationship with EEG defined attention lapses.
Design: Prospective, mixed design comparing apnea patients and control subjects over a 60-minute driving simulation task while continuously recording both driving performance and EEG measures.
Setting: Sleep disorders center.
Participants: 15 polysomnographically diagnosed obstructive sleep apnea patients (mean age 42 +/- 6 yrs.) and 15 healthy volunteers (mean age 38 +/- 6 yrs.).
Interventions: NA.
Measurements and results: A computer based driving simulator recorded lane position variability, speed variability, steering rate variability, and crash frequency. The frequency and duration of EEG-defined attention lapses were also measured. The results demonstrated that the apnea group had significantly greater variability in lane position, steering rate, and speed than the control group. The apnea group also had more crashes. In addition, the apnea group had more EEG-defined attention lapses of longer duration. Except for speed and steering rate variability, these differences increased over the 60-minute task. Measures of lane position variability and crash frequency had a significant positive correlation with attention lapse frequency and duration.
Conclusions: The driving simulation task unmasked and quantified marked performance impairments in the sleep apnea group that increased over time. The poor performance appeared related to the EEG-defined attention lapses. Lane position variability appeared to be the most sensitive measure for assessing and quantifying impairment. This study suggests that poorer driving performance and crashes are not entirely due to overt sleep, but inattention due to sleepiness.