Snoring loudly enough to wake members of your household is one sign that you have sleep apnea—a disorder that repeatedly interrupts your breathing throughout the night. These breathing disruptions can leave you groggy the next day, but they also pose serious risks to your heart.
Using a continuous positive airway pressure (CPAP) machine at night—while an established and effective fix for sleep apnea— might not help you avoid a heart attack or stroke as previously thought, new research finds.
The cardio connection
Of the two main types of sleep apnea, obstructive sleep apnea is the most common. The sleep disorder occurs when your tongue and other soft tissues in the back of your mouth fall back and block your airway—partially or totally stopping oxygen from entering your lungs. Your brain repeatedly jars you awake to restart your breathing, causing you to gasp or snore. However, even though your brain is arousing you, you may not remember these events occurring when you fully awaken in the morning. The other type of apnea, central sleep apnea, is caused by faulty signals from your brain to the muscles that control breathing.
Disrupted breathing and low blood oxygen levels could increase the risk for coronary artery disease, heart attack, stroke, heart failure, and sudden death. The association between sleep apnea and heart disease was first discovered nearly three decades ago and has been confirmed in several studies since then. What has been less clear is how CPAP might reduce heart risks.
CPAP for sleep apnea
CPAP, combined with weight loss, is a cornerstone of sleep apnea treatment. CPAP users wear a masklike breathing device over their nose or nose and mouth. A pump attached to the mask gently blows pressurized air into the airway to keep the throat open and oxygen flowing into the lungs while patients sleep.
CPAP has been shown to lower blood pressure, improve blood sugar control, improve depression and daytime sleepiness, and promote blood vessel health. Some studies comparing CPAP with no treatment have found lower rates of heart attack, stroke, and death in CPAP users. Yet, many of these studies weren’t rigorous enough to prove whether the treatment—or other healthy participant behaviors— was responsible for the heart risk reduction.
Australian researchers analyzed data from 10 randomized controlled trials—which are considered the most rigorous methods to determine cause and effect—in JAMA: The Journal of the American Medical Association in July 2017. The studies compared the effectiveness of CPAP versus standard care or sham (fake) CPAP in 7,266 people with sleep apnea. All the trials involved CPAP except one, which studied a less common device used for central sleep apnea. In total, the participants had 356 heart events, and 613 of them died. The participants’ ages ranged from 51 to 71, and 80 percent were men.
CPAP treatment didn’t reduce the incidence of heart attacks, strokes, or death—although it did improve sleep apnea symptoms like daytime sleepiness, anxiety, and depression. The authors say that their results with CPAP as a solo treatment for heart disease risk probably isn’t a good strategy.
However, a major study limitation was the short amount of time participants used CPAP—an average of three to four hours a night. This suggests the rest of the night was spent without CPAP, which could cancel out any benefit from using the device. All-night-long use is likely needed to see any reduction in heart risk.
An accompanying editorial also suggests the conclusion might be premature. Most participants in the review had moderate sleep apnea; people with more severe symptoms might respond better to treatment. It’s also possible that future studies will find a cardiovascular disease prevention benefit to using CPAP.
The study results shouldn’t scare you away from using CPAP to treat your sleep apnea. Though it might not reduce your heart risks, it can help you breathe better at night and feel more alert during the day. Research finds that CPAP helps 80 to 90 percent of people with sleep apnea.