OSA severity is linked to impaired autonomic capacity, while CPAP therapy selectively improves autonomic recovery dynamics, and sleepiness does not modify these adaptations, suggesting that CPAP enhances autonomic flexibility rather than reversing established autonomic impairment.
Key Findings
Results
Higher baseline AHI was independently associated with lower heart rate recovery at 1 minute (HRR1), heart rate recovery at 4 minutes (HRR4), and chronotropic response.
All associations were statistically significant (all p < 0.05)
Associations were independent of Epworth Sleepiness Scale (ESS) scores
Multivariable linear regression was used to examine baseline associations
The study included 322 CAD patients across three groups: non-sleepy OSA (n=100), sleepy OSA (n=130), and non-OSA reference (n=92)
Results
Post-exercise recovery time shortened significantly over the follow-up period during CPAP therapy.
The change in recovery time was statistically significant (p < 0.01)
Linear mixed-effects models were used to assess longitudinal changes
Standardized exercise testing was performed at 3 and 12 months
HRR1, HRR4, and chronotropic response showed no meaningful change over the same period
Results
Longitudinal trajectories of exercise-derived autonomic markers during CPAP therapy did not differ by sleepiness status.
Sleepy OSA patients were defined as ESS ≥ 10 (n=130) and non-sleepy as ESS < 10 (n=100)
Outcomes assessed included HRR1, HRR4, chronotropic response, and post-exercise recovery time
No significant interaction between sleepiness status and longitudinal autonomic adaptation was found
Results suggest sleepiness does not modify CPAP-related autonomic adaptations
Results
The association between OSA severity and autonomic dysfunction was independent of daytime sleepiness at baseline.
ESS was used as the measure of daytime sleepiness with a threshold of 10
AHI < 5 events/h defined the non-OSA reference group (n=92)
Moderate-to-severe OSA was the inclusion criterion for both CPAP-treated groups
Multivariable linear regression confirmed independence from ESS scores
Discussion
CPAP therapy appears to enhance autonomic flexibility through improved recovery dynamics rather than reversing established autonomic impairment.
Recovery time shortened significantly (p < 0.01) while HRR1, HRR4, and chronotropic response did not meaningfully change
The authors interpret this as CPAP selectively improving autonomic recovery dynamics
The study was conducted within the RICCADSA cohort of coronary artery disease patients
Follow-up assessments were conducted at 3 and 12 months post-CPAP initiation
What This Means
This research suggests that in patients with coronary artery disease (CAD) who also have obstructive sleep apnea (OSA), the severity of sleep apnea is directly linked to poorer heart rate control during and after exercise. Specifically, patients with more severe OSA showed reduced heart rate recovery after exercise and a blunted heart rate response during exercise — both signs of impaired autonomic (involuntary nervous system) function. Importantly, this relationship held regardless of whether patients reported feeling sleepy during the day.
When patients were treated with CPAP (a breathing device used during sleep for OSA), one specific measure — the time it took for the heart to recover after exercise — improved significantly over 12 months. However, other heart rate measures did not change meaningfully. This pattern was the same whether patients had daytime sleepiness or not, suggesting that feeling sleepy is not a key factor in how the heart responds to CPAP treatment.
This research suggests that CPAP therapy may improve the heart's ability to adapt and recover from physical stress, even if it does not fully reverse the underlying autonomic dysfunction caused by OSA. This has potential implications for how clinicians think about treating sleep apnea in heart disease patients: the benefits of CPAP on heart function may extend beyond just reducing sleepiness, and patients who do not feel sleepy may still benefit from treatment in terms of cardiovascular autonomic health.
Balcan B, Glantz H, Thunström E, Uzel H, Azarbarzin A, Peker Y. (2026). Exercise-derived autonomic recovery during CPAP therapy in coronary artery disease patients with OSA: Does sleepiness matter?. Sleep medicine. https://doi.org/10.1016/j.sleep.2026.109020