In today’s fast-paced society, sleep deprivation has become increasingly pervasive in our demanding daily routines. Whether we lose out on sleep because we don’t make it a priority or due to unwelcome stress, insomnia or sleep-disordered breathing, we put ourselves at a growing risk for several cardiovascular issues, including high blood pressure, stroke, atrial fibrillation, and heart disease.
Although it may be hard to believe that people spend around one-third of their lives sleeping, emerging research has begun to explain the complex inter-relationship and importance between sleep-disordered breathing and cardiovascular disease.
“Sleep is no longer considered a passive and homogenous state; instead it is understood to consist of cyclic periods of complex and changing brain activity, behavior and physiology,” says Shailendra Singh, MD, FACC, a Steward Health Care and Steward Medical Group interventional cardiologist. “Most people wonder how the cardiovascular system can be negatively affected during the seemingly benign activity of sleep. Uncontrolled sleep begins as a respiratory-related issue, most commonly termed sleep apnea or sleep disordered breathing. There are two main types of sleep apnea: obstructive and central.”
Obstructive sleep apnea (OSA) is the more common form associated with snoring and occurs due to the intermittent collapse of the upper airway, which translates to cessation or a significant decrease in airflow.
“Collapse of the upper airway may happen during the deep stages of REM sleep since we lose postural muscle tone, thus allowing the airway to become transiently limp,” says Dr. Singh. “Therefore, when we breathe in, the airway collapses on itself, and stays obstructed until we overcome the physical obstruction or when the brain actually wakes up momentarily.”
These episodes may occur hundreds of times nightly ‒ up to one to two times per minute – in patients with severe OSA. It is often accompanied by wide swings in heart rate, a quick decrease in oxygen saturation, and brief electroencephalographic (EEG) arousals associated with loud breathing sounds when the airway reopens, and air is exhaled.
When we continuously have hypoxemia (decreased oxygen levels in the bloodstream) and carbon dioxide retention accompanied by many brain awakenings throughout the night, our body’s reflex response is to increase the production of hormones, which also lead to sympathetic nerve activation. This, in turn, leads to increased blood pressure and heart rate, which over time can cause repetitive damage to blood vessels, structural damage to the heart, and cardiac arrhythmias thus leading to the possible sequelae of hypertension, atrial fibrillation, heart attack, stroke, and heart failure.
“We may think we have had a good night’s sleep and unknowingly brush off symptoms, including disruptive snoring, daytime sleepiness, fatigue, morning headache and confusion, which could be signs of sleep apnea,” explains Dr. Singh.
If you suspect you have a sleep disorder, talk to your primary care physician about scheduling a polysomnography (overnight sleep study) to accurately diagnose OSA and find the treatment that may be best for you.
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