Your heart does more than just beat – it adapts, responds, and restores itself while you sleep. But for millions of people, sleep isn’t a peaceful recovery period. Conditions like sleep apnea can disrupt vital nighttime rhythms and place real strain on the heart.
The link between disordered sleep and heart rhythm problems is both mechanical and chemical: shifts in oxygen levels, pressure changes in the chest, and surges of stress hormones can all destabilize the heart’s electrical patterns. Over time, these disturbances increase the likelihood of arrhythmias, from brief pauses to persistent conditions like atrial fibrillation.
Even if you feel rested in the morning, what happens during the night could be challenging your heart’s ability to keep pace.
The Sleeping Heart
When you drift off at night, your heart shifts gears. In healthy sleep, your heart rate slows, blood pressure drops, and your nervous system favors a more relaxed state. This relaxation is driven by a shift from sympathetic (“fight-or-flight”) dominance during the day to a “rest-and-reset” phase at night, which lowers overall metabolic demand and conserves energy. This nightly reset helps reduce wear and tear on the cardiovascular system.
Sleep also supports your heart’s rhythm. During non-REM sleep, the deepest and most restorative sleep stage, your body leans into that parasympathetic state of rest and reset. In this phase, baroreceptor sensitivity increases – pressure-sensitive sensors in blood vessels become more responsive to changes in blood pressure, helping the body adjust heart rate and vessel dilation to maintain steady circulation. This allows the body to finely regulate blood pressure, and respiratory patterns become more regular, contributing to stable oxygen delivery.
The vagus nerve also works to keep things calm, helping to regulate steady beats and prevent unnecessary electrical surges.
But if your brain and body keep waking up, even briefly, the heart doesn’t get the chance to rest. These frequent arousals disrupt normal autonomic balance, causing repeated sympathetic surges that can spike heart rate and blood pressure unexpectedly. When that pattern repeats night after night, the stress builds up in ways that aren’t always obvious until symptoms appear – or a serious rhythm problem does.
… Versus a Sleepless Heart
Sleep apnea is a serious condition in which breathing repeatedly stops and starts throughout the night, often without the person being aware of it. These pauses can last for several seconds to over a minute and may happen dozens, or even hundreds, of times per sleep cycle.
When breathing stops, oxygen levels drop. The brain reacts by briefly waking the body just enough to resume breathing. That jolt triggers a surge of stress hormones like adrenaline, increases blood pressure, and activates the sympathetic “fight-or-flight” system – again and again, all night long.
This repeated arousal cycle is what links sleep apnea to arrhythmias. Every time the airway collapses and oxygen dips, the heart’s electrical system is thrown off balance. The combination of low oxygen, surging blood pressure, and nervous system stress sets the stage for irregular heartbeats.
Atrial fibrillation (AFib) is the most common rhythm issue connected to sleep apnea. In fact, people with untreated sleep apnea are up to four times more likely to develop AFib.1Other rhythm disturbances, such as bradycardia (a slow heartbeat), pauses, and premature beats, are also more common in those with sleep-disordered breathing.
Treating sleep apnea can significantly reduce these risks. Studies show that people with both sleep apnea and AFib who use their CPAP (continuous positive airway pressure) machines consistently are less likely to experience recurrent arrhythmias.1
Inflammation, Oxidative Stress, and Heart Remodeling
Sleep apnea’s impact on the heart extends well beyond breathing interruptions. The repeated oxygen drops trigger a cascade of biological responses that create a more arrhythmia-prone environment.
Intermittent hypoxia (the cyclical dips in blood oxygen) promotes the generation of reactive oxygen species (ROS), highly reactive molecules that cause oxidative stress. This oxidative stress damages heart cells and contributes to autonomic nervous system dysfunction, further destabilizing heart rhythms.1
At the same time, sleep apnea elevates inflammatory markers such as C-reactive protein (CRP), interleukin-6 (IL-6), and tumor necrosis factor-alpha (TNF-α). These molecules are part of the body’s immune response – CRP signals general inflammation, IL-6 promotes fever and stimulates immune cell activity, and TNF-α can induce cell death and inflammation. An increase in these markers induces chronic inflammation, which encourages fibrosis (scarring in the heart’s atrial tissue). This scarring disrupts normal electrical conduction pathways and raises the risk for atrial fibrillation.1
Chronic inflammation also contributes to endothelial dysfunction, which impairs the inner lining of blood vessels, reducing their ability to regulate blood flow and pressure effectively. This dysfunction can promote hypertension and increase the workload on the heart, further destabilizing its rhythm. Additionally, ongoing inflammation can disrupt the balance of autonomic nervous system signals, worsening the irregular electrical activity in the heart. These combined effects increase susceptibility not only to atrial fibrillation but also to other arrhythmias and cardiac complications.1
This interplay between oxidative stress and inflammation also promotes structural remodeling of the heart. Surges in blood pressure and sympathetic nerve activity during obstructive sleep events stretch and strain cardiac chambers. Over time, this remodeling alters the heart’s size, shape, and electrical properties, setting the stage for persistent arrhythmias.
Studies involving treatment with CPAP have demonstrated a reduction in oxidative stress and inflammation, emphasizing its function not only in improving breathing but also in mitigating the cellular damage that contributes to heart rhythm problems.
Get Into a Healthy Rhythm
A good night’s sleep feels great, but it’s also essential for maintaining a healthy, steady heart rhythm. Sleep apnea disrupts this vital process through repeated breathing interruptions, triggering a cascade of stress responses that strain the heart. From oxygen drops to inflammatory surges and structural changes in heart tissue, the effects are far-reaching and increase the risk of arrhythmias, both dangerous and benign.
For anyone with known sleep apnea or symptoms like loud snoring, daytime fatigue, or pauses in breathing during sleep, seeking evaluation and management is an important step toward protecting cardiovascular health.
Dr. Tordini is a part of Florida Medical Clinic, Orlando Health.
1Geovanini, G. R., & Lorenzi-Filho, G. (2018). Cardiac rhythm disorders in obstructive sleep apnea. Journal of thoracic disease, 10(Suppl 34), S4221–S4230. https://doi.org/10.21037/jtd.2018.12.63.