President Biden has sleep apnea, according to a spokesperson, and used a CPAP machine as recently as Tuesday night. 

"Since 2008, the President has disclosed his history with sleep apnea in thorough medical reports. He used a CPAP machine last night, which is common for people with that history," White House deputy press secretary Andrew Bates told Fox News.

Approximately 30 million people in the U.S. are believed to have the condition, according to the American Medical Association. 

However, just around 6 million are diagnosed with sleep apnea.

BIDEN USED CPAP MACHINE FOR SLEEP APNEA, EXPLAINING FACE MARKS

Biden with sleep apnea strap mark

President Biden speaks with members of the media before boarding Marine One on the South Lawn of the White House in Washington, Wednesday, June 28, 2023, for a short trip to Andrews Air Force Base, Maryland, and then on to Chicago. Biden has started using a continuous positive airway pressure, or CPAP, machine at night to help with sleep apnea, the White House said Wednesday after indents from the mask were visible on his face. (AP Photo/Andrew Harnik)

So, what is sleep apnea? 

During sleep, a person's breathing stops and restarts many times, according to the National Heart, Lung and Blood Institute. The condition can prevent the body from getting enough oxygen. 

There are two types of sleep apnea: obstructive sleep apnea and central sleep apnea. 

With obstructive sleep apnea, the most common, the upper airway becomes blocked many times, reducing or completely stopping airflow. Anything that could narrow and airway can increase the risk for obstructive sleep apnea, including large tonsils, obesity and changes in hormone levels. 

Central sleep apnea occurs when the brain does not send the signals needed to breathe and health conditions that impact how the brain controls the airway and chest muscle can cause central sleep apnea. 

CPAP machine

Jenny Shields poses for a photo of her CPAP machine, which was recalled for safety reasons, at her home in Wilmington, Delaware, on June 3, 2022. (Rachel Wisniewski/For the Washington Post)

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Factors like age, family history, heart or kidney failure, sex and lifestyle habits raise the risk of obstructive sleep apnea. Men are more likely to have serious sleep apnea and to get sleep apnea at a younger age than women.

Age, family history, lifestyle habits, health conditions, opioid use and those who were born prematurely also have a raised risk of central sleep apnea.

Frequent loud snoring may be a sign of sleep apnea, and symptoms include breathing that starts and stops, gasping for air during sleep, daytime sleepiness and tiredness, dry mouth or headaches, decreased libido or sexual dysfunction or waking up often during the night to urinate. 

Biden speaking with reporters

President Biden speaks with members of the media before boarding Marine One on the South Lawn of the White House in Washington, Wednesday, June 28, 2023, for a short trip to Andrews Air Force Base, Maryland, and then on to Chicago. (AP Photo/Andrew Harnik)

Breathing devices, including continuous positive air pressure (CPAP) machines and lifestyle changes, are common treatments. 

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A CPAP is a motorized device that pumps air through a mask to open a sleeper’s airway, and about 5 million Americans have used them.

If those do not work, surgery may be recommended. 

A third of U.S. adults report that they usually get less than the recommended amount of sleep, according to the Centers for Disease Control and Prevention. 

Fox News' Adam Sabes, Patrick Ward and The Associated Press contributed to this report.