O054 Slow-wave recovery after CPAP in OSA—a high-density EEG study

Abstract Background and objective People with obstructive sleep apnoea (OSA) exhibit deficits in slow-wave activity during NREM sleep. High-density electroencephalography (hdEEG) studies have previously demonstrated regional recovery of sleep microarchitecture following effective continuous positive airway pressure (CPAP) therapy. Our study aimed to evaluate the changes in slow-wave characteristics during N3 sleep after 3 months of CPAP. Methods Ten adult males with moderate-to-severe OSA (age 51.2 ± 6.7, BMI 31.2 ± 5.1) underwent sleep and resting wake recordings using 256-channel hdEEG and cognitive tasks at baseline and after CPAP. After artefact processing, all-night HdEEG data were analysed using a validated automated slow wave event detection algorithm. Slow-wave events (1–4.5 Hz) during N3 sleep were identified for each electrode and parameters of density, amplitude, peak frequency, and peak to peak amplitude were computed. Regional and global differences in slow-wave parameters during N3 were assessed using paired t-tests and statistical nonparametric mapping. Results There was an increase in global measures of the number of slow-waves (baseline: 367 ± 156 vs. CPAP: 617 ± 265, p=.02) and slow-wave density (baseline: 3.9 ± 1.2 vs. CPAP: 5.1 ± 1.3 events/minute, p=.01) during N3 sleep following 3 months of CPAP. Regional analysis showed higher slow-wave density across the frontal and bilateral temporal–parietal regions, extending to posterior regions after CPAP. No significant differences in other slow-wave parameters were observed. Conclusion These preliminary findings suggest recovery of slow-wave density during N3 sleep in males with moderate-to-severe OSA following 3 months of CPAP. Further analyses to explore the relationship between these neurophysiological changes and neurocognitive recovery are planned.