Obstructive Sleep Apnea (OSA) is a condition that impacts more people than you might think. Estimated to affect about 4 to 7% of the general population, its prevalence jumps to a staggering 30 to 40% among those with hypertension. In fact, roughly half the individuals diagnosed with OSA also struggle with high blood pressure.
At night, in a healthy person, blood pressure typically dips by about 10 to 20%. This natural decrease is known as “blood pressure dipping.” However, this isn’t the case for individuals with severe OSA. Their blood pressure drops less than 10%, a condition called “nondipping,” which unfortunately increases their risk for cardiovascular issues.
But that’s not all. Many with OSA experience a sharp rise in blood pressure upon waking, referred to as a “morning surge.” This surge, combined with a pattern of nondipping blood pressure, can significantly heighten the risk of cardiovascular diseases. In fact, moderate to severe OSA is linked to increased overall mortality, particularly from cardiovascular causes.
OSA’s impact isn’t limited to nighttime. Studies have shown that daytime blood pressure also rises in correlation with the severity of sleep apnea. This condition places an extra strain on the heart, particularly due to the over-activation of the sympathetic nervous system, which manages our “fight or flight” response. When triggered, it causes several temporary physical changes like a faster heartbeat, higher blood pressure, dilated pupils, and increased metabolism. These are all part of our body’s natural response to stress. However, when the sympathetic nervous system is overstimulated, as in the case of OSA, it can lead to chronically elevated blood pressure.
Each episode of airway collapse in OSA momentarily halts breathing during sleep, which in turn activates the sympathetic nervous system, causing a rapid spike in blood pressure. This can often wake a person from sleep, further exacerbating the activation of the sympathetic nervous system and leading to even higher blood pressure levels.
Moreover, OSA disrupts sleep and triggers the release of catecholamines, stress hormones produced by the adrenal glands, into the bloodstream. These hormones, including dopamine and epinephrine (adrenaline), contribute to high blood pressure when their levels are elevated.
The good news? There are effective treatments for OSA. The most common and successful is continuous positive airway pressure (CPAP), which not only enhances sleep quality but can also aid in managing hypertension. CPAP therapy works by keeping the airway open and preventing those dangerous dips and surges in blood pressure, thereby reducing the risk of cardiovascular complications associated with OSA.