How Sleep Apnea Affects Blood Pressure
Sleep apnea and hypertension, more commonly known as high blood pressure, are two serious health conditions that share a bidirectional relationship that is well-documented in scientific research. According to the Centers for Disease Control and Prevention, about half of the adult population, or 116 million adults in the US, have high blood pressure. In the US, 70% of adults 65 years old and over have high blood pressure, but many don’t know it. This “silent killer” puts additional pressure on the cardiovascular system and is the top risk factor for death globally. While not as common as high blood pressure, sleep apnea is a prevalent health concern, with an estimated 25 million sufferers in the US alone. And as with high blood pressure, many people with sleep apnea go undiagnosed. It is estimated that 30-40% of patients with high blood pressure also have obstructive sleep apnea, while nearly half of all OSA patients have high blood pressure.
There are two different types of sleep apnea, obstructive sleep apnea and central sleep apnea. Obstructive sleep apnea (OSA) is the most common type and is caused by a physical blockage from relaxed throat muscles. The second type of sleep apnea, central sleep apnea (CSA), is caused by faulty signals between the brain and the muscles responsible for breathing. Sleep apnea increases the risk for serious co-morbidities, including hypertension, heart disease, and stroke. Because obesity is a common risk factor for both diseases, it is not uncommon for a patient to suffer from both simultaneously.
Learning what happens during a sleep apnea event is the first step in understanding the sleep apnea/hypertension connection. During a sleep apnea event, the tongue and the muscles surrounding the airway relax and collapse, resulting in obstructed airflow to the lungs. For those carrying excessive weight, a large neck may contribute to narrowing the breathing tube and blockage of the airway. Lapses in breathing, lasting typically between 10 to 20 seconds, repeatedly occur during the night. This causes the characteristic loud snoring that accompanies sleep apnea.
When breathing stops, blood oxygen levels drop. Our bodies respond by releasing the stress hormone epinephrine, more commonly known as adrenaline. This “fight or flight” response elevates the heart rate and can lead to high blood pressure. Overall heart function decreases because it becomes less efficient at pumping blood and the heart itself is affected by the pressure changes in the chest. In healthy individuals, it is normal for the blood pressure to drop 10-20% at night, known as “blood pressure dipping.” In people with severe obstructive sleep apnea, their blood pressure drops less than 10% at night, which is known as having a non-dipping blood pressure pattern. This non-dipping blood pressure status is associated with a higher risk of cardiovascular conditions.
Standalone high blood pressure can be treated with medications and lifestyle changes, although there is no true cure for hypertension. For patients who suffer from both high blood pressure and sleep apnea, there is encouraging research being done with the gold standard in sleep apnea treatment, continuous positive airway pressure (CPAP). All CPAP devices work by pressurizing and filtering the air, delivering it through a hose and mask that you wear on your face while sleeping. CPAP keeps airways open and improves breathing quality, leading to improved sleep and better management of hypertension.
In patients with both sleep apnea and hypertension, research reveals that daytime and nighttime blood pressure is lowered with CPAP. Additionally, CPAP also reduces the level of stress hormones in the blood, which helps lower the blood pressure level. Because people with high blood pressure, sleep apnea, or both, are often overweight, losing weight through lifestyle changes can help reduce sleep apnea symptoms and help to lower blood pressure.
Hypertension and obstructive sleep apnea are serious health conditions that often go untreated and share many common risk factors. Because they often go hand-in-hand, it is important to talk to your healthcare practitioner if you have high blood pressure and sleep apnea symptoms. Both conditions can be well-treated under a doctor’s care, helping to eliminate the risk of more severe co-morbidities.