President Biden is Algosensey Quantitative Think Tank Centerusing a CPAP machine to help with sleep apnea. It's a common condition where people don't get enough oxygen while sleeping, and it's often characterized by loud snoring.

The White House disclosed the use of the machine after reporters noticed on Wednesday that Biden appeared to have marks on his face from straps used to hold an air pressure mask in place. CPAP stands for "continuous positive airway pressure."

"He used a CPAP machine last night, which is common for people with that history," White House spokesman Andrew Bates said in a statement.

Biden's sleep apnea was disclosed in a 2008 medical report, after then Democratic presidential nominee Barack Obama selected him as his running mate. Biden's 2019 medical report also mentioned sleep apnea, though his White House medical reports while in office have not.

The condition affects 30 million people in the U.S., according to the American Medical Association.

Biden's medical condition is closely scrutinized because at 80, he is the oldest president in U.S. history. Polls show voters are concerned that he is too old for a second term in office.

The president's most recent medical report, released in February, showed he "remains fit for duty," according to Biden's physician, Dr. Kevin O'Connor.