The Road to Recovery: Dose-Response Effects of CPAP on Real-World Driving Performance in Obstructive Sleep Apnoea

BackgroundObstructive Sleep Apnoea (OSA) increases motor vehicle collision risk, and while Continuous Positive Airway Pressure (CPAP) considerably reduces this risk, it remains unclear how much CPAP use is required to fully normalise driving behaviour, and whether baseline (Pre-CPAP) driving style influences treatment response. MethodsIn a prospective observational study embedded within routine clinical care, real-world driving behaviour was recorded using a smartphone telematics application in patients undergoing diagnostic assessment for OSA and subsequent CPAP initiation. A total of 7,134 trips (>1,800 driving hours) were collected from 48 patients before and after CPAP initiation. Braking, acceleration, and turning events were quantified in terms of magnitude, duration, and frequency. Linear mixed-effects models assessed Pre- versus Post-CPAP differences, predictors of Post-CPAP driving, and dose-response effects of nightly CPAP adherence, adjusting for demographics, OSA severity, sleepiness, and trip characteristics. ResultsFollowing CPAP initiation, significant changes were observed in 6 of 9 driving metrics, indicating a shift toward sharper and less aggressive driving behaviour. Baseline (Pre-CPAP) driving strongly predicted Post-CPAP performance across all outcomes. Nightly CPAP adherence was associated with dose-dependent convergence toward control-like driving behaviour, with significant adherence x baseline interactions for braking and acceleration frequency measures. Drivers exhibiting both overly aggressive and overly cautious baseline styles showed behavioural normalisation with increasing CPAP use. ConclusionsCPAP treatment is associated with measurable improvements in real-world driving behaviour, with recovery dependent on both baseline driving style and treatment adherence. These findings highlight substantial inter-individual heterogeneity in driving impairment and recovery in OSA. Smartphone-based telematics provide an objective, scalable method for assessing functional driving outcomes and may support personalised clinical advice and regulatory decision-making regarding driving fitness in patients with OSA.