Why sleep is important to your heart

Rodney Harrison, MD

Cardiology

Heart disease is a leading cause of death in the United States, among men and women alike. Risk factors for heart disease include:

• Hypertension (high blood pressure)
• Diabetes
• High cholesterol
• Smoking
• Family history

While you may be familiar with these risk factors, insufficient sleep can greatly impact your heart as well. Cardiologist and board-certified sleep physician Rodney Harrison, MD, explained why sleep apnea is a major risk factor for heart disease.

“Sleep apnea is when you stop breathing or have difficulty breathing during the night, typically five times or more per hour,” Dr. Harrison said.

Factors that increase your risk of sleep apnea include:

• Obesity – Increased fat deposition obstructs your airway.
• Gender – Men are more prone to sleep apnea at an earlier age because testosterone affects the way fat is deposited in their necks. Post-menopausal women have increased testosterone levels which will affect fat deposition around their airways as well.
• Age – Decreased elasticity of muscles.

Sleep apnea is categorized into three levels (mild, moderate and severe) based on the number of times a patient stops breathing each hour. 5–15 times is mild, 16–30 is moderate and more than 30 is severe.

“All levels of sleep apnea can be a predisposition for heart disease. While this may seem strange, consider what is happening to your body,” Dr. Harrison said. “When you go to sleep and you stop breathing, your body is put under great stress. It’s no different than someone putting a pillow over your mouth and choking you in the middle of the night. This kind of stress leads to an adrenaline release, which causes your blood pressure and heart rate to increase. This is often described as a fight or flight response.”

The inability to breathe also causes the liver to release high levels of glucose, which may lead to insulin resistance or pre-diabetes.

“That stress is coming again from the adrenaline telling your body to release sugar to give you energy. When your body releases sugar, you release insulin. Sugar. Insulin. All through the night.”

Dr. Harrison explained that sleep apnea also can cause your heart to jump out of rhythm. This is known as atrial fibrillation, causing the two chambers to beat irregularly. An irregular heartbeat causes blood to stagnate, which can predispose to clots and, ultimately, a stroke.

Sleep is an integral part of a healthy lifestyle. Dr. Harrison recommends that adults get about seven to eight hours of uninterrupted sleep a night. “If you snore, wake several times throughout the night or have excessive fatigue, you should ask your doctor about sleep apnea,” he said.