What happens during sleep apnea
In obstructive sleep apnea (OSA), the upper airway repeatedly collapses during sleep. The patient continues trying to breathe against a closed airway, generating large negative pressures in the chest. Oxygen drops, carbon dioxide rises, and the body responds with a burst of adrenaline that briefly arouses the person enough to reopen the airway. Then sleep resumes — and the cycle repeats. In severe cases, this happens dozens of times per hour, all night, every night.
Each cycle does three things relevant to heart rhythm:
- Negative-pressure stretch on the heart and great vessels — the atrium gets pulled outward with every blocked breath.
- Sympathetic surges — repeated bursts of adrenaline raise heart rate, blood pressure, and trigger irritable atrial cells to fire.
- Oxygen swings — the atrium does not love being repeatedly under-oxygenated.
Over time these changes remodel the atrium electrically and structurally, creating a substrate that is ripe for AFib.
What the evidence shows
The data here is strong:
- About half of patients with AFib have at least moderate obstructive sleep apnea, and most are undiagnosed at the time of their AFib evaluation.
- Cohort studies show that untreated OSA is associated with a substantially higher rate of new AFib, and that AFib episodes cluster during sleep in patients with OSA.
- After AFib ablation, untreated OSA roughly doubles the recurrence rate. CPAP use brings the recurrence rate close to that of patients without OSA.
- Treating OSA reduces blood pressure, improves daytime energy, and reduces cardiovascular events — all of which matter beyond rhythm.
Signs that should prompt testing
We have a low threshold for ordering a sleep study, because we know how often it changes management. Common clues:
- Loud snoring, witnessed pauses in breathing, or gasping at night (often reported by a partner before the patient notices).
- Daytime sleepiness, morning headaches, dry mouth, fatigue.
- AFib episodes that happen overnight or are present on waking.
- Resistant hypertension — blood pressure that does not respond to several medications.
- Body habitus, neck circumference, jaw structure that predispose to airway collapse.
- Atrial fibrillation in someone who otherwise has no obvious risk factors.
Importantly, a meaningful fraction of patients with OSA are thin and do not snore. We have learned not to rule it out based on appearance.
Testing
Most patients can be diagnosed with a home sleep test — a small device worn overnight at home that measures airflow, oxygen, heart rate, and effort. It is simple and well tolerated. In more complex situations (central apnea, suspicion of other sleep disorders), we order a full in-lab polysomnography.
The result is summarized by the AHI (apnea-hypopnea index) — the number of apneic or hypopneic events per hour. Five or more is abnormal; fifteen or more is moderate; thirty or more is severe.
Treatment
- CPAP (continuous positive airway pressure) remains the most effective treatment for moderate-to-severe OSA. Modern machines are quieter, smaller, and far more tolerable than older generations. Mask fit and a willing trial usually solve the comfort issues that prevent people from sticking with it.
- Oral appliances — dental devices that hold the lower jaw forward — work well for mild-to-moderate OSA and for patients who cannot tolerate CPAP.
- Weight loss can dramatically improve or even resolve OSA in many patients.
- Positional therapy — devices that keep you off your back — helps when apnea is positional.
- Hypoglossal nerve stimulation (an implantable device) is an option for selected patients who can’t use CPAP.
The key with any treatment is regular use. CPAP that sits on the nightstand does not help. We aim for at least four hours of use per night, every night, and ideally all night.
Practical steps
- Mention snoring or sleepiness at your appointment — we want to know.
- If a partner notices breathing pauses, that is a strong sign and worth telling us about.
- If you are scheduled for an AFib ablation and have not been screened for OSA, ask about it. Treating OSA before and after ablation meaningfully changes outcomes.
When to check in with us
Tell us if you have been diagnosed with sleep apnea, whether you are using CPAP, and how many hours per night. Bring your CPAP compliance report to a visit if you have one — most machines have an app that tracks it. We coordinate with the sleep medicine team to keep the rhythm and the sleep working together.