Joe Biden sleeping in an air mask due to sleep apnea

US President Joe Biden speaks about the economy at the Old Post Office in Chicago, Illinois, on June 28, 2023.

The White House on Wednesday put to bed speculation about a mystery line on President Joe Biden's face, explaining that he has begun wearing a CPAP device to help ward off sleep apnea.

The faint horizontal line, like a shallow indentation, was noticed by reporters seeing 80-year-old Biden up close earlier this week and again Wednesday as he departed the White House to give an economic speech in Chicago.

Deputy Press Secretary Andrew Bates said Biden was using a CPAP machine, referring to a widely used medical device to prevent snoring and the potentially damaging interruptions in breathing caused by sleep apnea. CPAPs include a mask with straps that cross the face.

Bates said that Biden has "disclosed his history with sleep apnea in thorough medical reports" since 2008.

"He used a CPAP machine last night, which is common for people with that history."

As the oldest president ever in the White House and seeking another four years in office in the 2024 election, Biden's health is under constant scrutiny.