President Joe Biden is one of many millions of people who have sleep apnea, a serious sleep disorder in which people stop breathing for 10 seconds or more at a time.

It’s estimated that at least 25 million American adults and 936 million adults between the ages of 30 and 69 worldwide may suffer from obstructive sleep apnea, with many more people undiagnosed.

The condition is called “obstructive” sleep apnea because unlike central sleep apnea — in which the brain occasionally skips telling the body to breathe — obstructive sleep apnea is due to a blockage of the airways by weak, heavy or relaxed soft tissues.

Muscle tone weakens with age, including in the soft palate and neck, making sleep apnea common among people older than 50, experts say. However, studies have found sleep apnea in the elderly tends to be of a mild to moderate kind, with the more severe cases occurring at younger ages.

Biden’s getting treatment

If left untreated, obstructive sleep apnea raises the risk of hypertension, heart disease, type 2 diabetes, depression and even an early death, according to the American Academy of Sleep Medicine.

The condition leads to dozens of “micro-awakenings” during the night that interrupt the body’s ability to complete a full sleep cycle. Symptoms include excessive daytime sleepiness, loud, raucous snoring, waking up with a dry mouth or sore throat, and morning headaches, according to the Mayo Clinic.

With treatment, however, breathing returns to normal and deep sleep can be achieved.  Weight loss can significantly decrease — or even eliminate obstructive sleep apnea, as the loss of tissue mass in the mouth, tongue and neck eases pressure on the airway. Doctors can also prescribe an oral appliance designed to enlarge the airway by moving the tongue or jaw forward.

If anatomical issues, such as nasal polyps, enlarged tonsils or adenoids, or a deviated septum, are contributing to the apnea, surgery may be recommended.

Mild cases of sleep apnea may respond to “positional therapy,” a fancy way of saying keeping sleepers on their sides instead of back during sleep, which can improve airway flow and reduce snoring.

One of the most common treatments is a continuous positive airway pressure machine, or CPAP, which relies on a hose and mask to deliver constant and steady air pressure to keep the airway open while a person sleeps. Today the machines are so sophisticated that a physician can remotely monitor a person’s sleep and help them adjust the air pressure.

The machines are thought to improve a number of complications associated with sleep apnea, including daytime fatigue, high blood pressure and sexual dysfunction, experts say.

Why is deep sleep important?

During the first and second stages of sleep, the body starts to decrease its rhythms. Doing so leads to the third stage — a slow-wave or deep sleep where the body is literally restoring itself on a cellular level — fixing damage from the day’s wear and tear and consolidating memories into long-term storage.

Years of research have found sleep, especially the deepest and most healing kind, boosts immune functioning. Slow-wave sleep is also the time when the body “takes out the trash” in the brain, including the beta-amyloid protein, one of the hallmark signs of Alzheimer’s disease.

Deep sleep is considered one of the best markers of sleep quality, because a person must typically have relatively uninterrupted sleep to achieve it. Since each sleep cycle is roughly 90 minutes long, most adults need seven to eight hours of relatively uninterrupted slumber to achieve restorative sleep, according to the US Centers for Disease Control and Prevention.

People with sleep apnea, however, can stop breathing 30 or more times an hour during the night, often wakening as they snore, snort or gasp for breath.

The constant interruption makes it difficult to get enough deep sleep and progress to the final stage, called rapid eye movement or REM sleep, which is when dreams occur. Studies have shown that missing REM sleep may lead to memory deficit and poor cognitive outcomes as well as heart and other chronic diseases and an early death.

Most people have no idea they are experiencing sleep apnea, which is why it’s important for loved ones to speak up if snoring is extremely loud or if a loved one stops breathing for short periods of time during the night. Anyone with symptoms of sleep apnea need to be evaluated by a sleep specialist.