En español | Sleeping is anything but restful for people with sleep apnea — in fact, it poses serious health risks for more than 18 million Americans. That’s the number of people whom doctors believe are living with sleep apnea, and many of them may be undiagnosed.

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Sleep apnea causes repeated pauses in breathing throughout the night. The pauses, which can happen 100 or more times per hour, occur when your airway is blocked (often by the tongue) or too narrow to allow normal breathing.

While men are more likely to be diagnosed with sleep apnea, the rates for women increase after menopause when hormonal changes affect muscle tone, making the airway more likely to collapse during sleep

In addition to disrupting your sleep, undiagnosed sleep apnea has been linked to high blood pressure, stroke, memory problems and diabetes.

Watch for these seven signs you may have sleep apnea:

#1: Your partner complains about loud or chronic snoring

A spouse is often the first person to know something is wrong, according to Michael Twery, Ph.D., director of the National Center on Sleep Disorders Research in the National Heart, Lung and Blood Institute’s Division of Lung Disease at the National Institutes of Health. “Snoring is a milder form of airway obstruction; the sound comes from the tissue vibrating as air passes over [a narrowed airway],” he explains. “If you’re snoring loudly, chronically and keeping your partner awake, it could be a sign of sleep apnea and you should talk to your doctor.”

#2: You gasp for air

In sleep apnea, it’s common for pauses in breathing to be followed by gasping, choking or snorting. “When the oxygen in your blood falls during breathing pauses, it signals your brain to wake up very briefly and draw a breath,” notes Clete Kushida, M.D. Ph.D., medical director of the Stanford Sleep Medicine Center. “Frantically trying to draw a breath can make you start gasping, snorting or choking to try to get air.”

In severe cases, you may experience frenzied gasps for air every 15 to 30 seconds throughout the night. If your partner notices difficulty breathing during your sleep, or if your breathing is stopping altogether, “you may want to discuss your symptoms with a physician,” says Twery.

Next: Five more signs of sleep apnea. »