The Hidden Danger: How Sleep Apnea Affects Cardiovascular Health

Sleep disorders, particularly sleep apnea, pose a significant yet often overlooked threat to cardiovascular health. One of the most concerning impacts is their connection to high blood pressure (hypertension). When breathing repeatedly stops and starts during sleep, as seen in obstructive sleep apnea, oxygen levels drop, triggering the body’s stress response. This leads to the release of stress hormones and increased heart workload, ultimately causing blood pressure to rise. Over time, untreated sleep disorders can contribute to persistent hypertension, raising the risk of heart disease, stroke, and other serious complications. Recognizing and addressing sleep disorders is crucial for maintaining optimal cardiovascular health.

High blood pressure and sleep disorders

Even without noticeable symptoms, a high blood pressure diagnosis—perhaps during a routine check-up—should be a wake-up call. As the leading risk factor for heart disease, high blood pressure increases the risk of circulatory diseases, the most common cause of death in Europe. Treatment is crucial, yet many wonder about its origins. Beyond classic factors like lack of exercise and high salt intake, sleep-related breathing disorders can also contribute. Poor sleep and high blood pressure are closely linked—hypertension can disrupt sleep, but more often, sleep disorders, especially breathing-related ones, drive high blood pressure.

Sleep apnea and high blood pressure

Sleep-related breathing disorders have been a known risk factor for high blood pressure for over 20 years. Half of sleep apnea patients have hypertension, and 30-40% of hypertensive patients have sleep apnea¹ ². The more severe the apnea, the higher the risk of hypertension³. Sleep apnea is common in those whose blood pressure is not controlled despite drug treatment, it is also referred to as therapy-resistant hypertension⁴.

CPAP and Renal Denervation in OSAS-Related Hypertension

Obstructive sleep apnea syndrome (OSAS) is a common disorder that contributes to secondary hypertension through intermittent hypoxia and excessive sympathetic activation. Blood pressure rises, increasing the risk of cardiovascular diseases like atrial fibrillation and heart failure. Sleep apnea contributes to hypertension through sympathetic activation, oxidative stress, inflammation, and vascular dysfunction.

Continuous positive airway pressure (CPAP) is the first-line treatment, effectively reducing blood pressure (BP) by improving nocturnal oxygenation and decreasing sympathetic overactivity. Studies show that CPAP significantly lowers nighttime BP and cardiovascular risk, particularly in patients with severe OSAS.

Renal denervation (RDN) has been explored as an alternative therapy for resistant hypertension, including cases associated with OSAS. Although small studies suggest RDN may reduce BP and apnea severity, its effectiveness is limited compared to CPAP. RDN mainly targets renal sympathetic activity, while OSAS-induced hypertension involves broader mechanisms, including central nervous system activation. Meta-analyses indicate that CPAP achieves greater BP reduction than RDN, making it the preferred option. However, in patients with OSAS and true resistant hypertension, combining CPAP and RDN may offer additional benefits⁵.

The Importance of Ruling Out OSAS as a Secondary Cause of Hypertension

Obstructive sleep apnea syndrome (OSAS) is a common but often overlooked cause of secondary hypertension. Up to 50% of individuals with OSAS have high blood pressure, and the condition is particularly prevalent in patients with drug-resistant hypertension. OSAS leads to repeated oxygen deprivation, triggering sympathetic nervous system activation, oxidative stress, and vascular dysfunction—all of which contribute to elevated blood pressure.

Identifying and treating OSAS is crucial, as standard antihypertensive therapies may be less effective if the underlying sleep disorder remains unaddressed. Continuous positive airway pressure (CPAP) therapy has been shown to improve blood pressure control in OSAS patients, reducing cardiovascular risk. Therefore, screening for OSAS should be a standard part of hypertension management, especially in cases of resistant or uncontrolled high blood pressure.

Insomnia and too little sleep can also contribute to high blood pressure

Insomnia is a common sleep disorder, affecting about 6% of the population, and is more common in women. It’s defined by difficulty falling or staying asleep at least three nights a week for a month. Those affected often experience irritability, fatigue, and difficulty focusing, impairing the quality of life and well-being.

On the one hand, one key factor raising blood pressure in insomnia is insufficient sleep. A study⁶ 15 years ago came to the conclusion that a sleep duration of less than five hours increases the risk of hypertension by over 50 percent.

On the other hand, high blood pressure can lead to insomnia. Adults with hypertension had a 1.5 to 3-fold increased risk of this sleep disorder ⁷ ⁸. There are many causes of insomnia. People with insomnia should therefore always consult their family doctor.

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