Fans were standing up in front of the slumbering fan, cheering as the Kansas City Chiefs battled the San Francisco 49ers.
The video went viral, as it has been viewed more than 5 million times, with 72,000 times and shared more than 13,000 times on Twitter.
The fan, who has not been identified, woke up moments later, Maxwell tweeted.
"He just woke up ... oh no, should I tell him?" Maxwell tweeted.
It was not clear which team the fan was rooting for, but there is a good chance he stayed awake for the rest of the game.
The Chiefs rallied from a 10-point deficit in the fourth quarter, scoring three touchdowns in the final 6:13 of the game, to win 31-20.
She didn’t have to. A friend showed the fan the 13-second clip.
“The whole section knows,” Maxwell wrote.
Maxwell said she later attempted to interview the man after halftime, but the fan was having none of that.
"He was clearly annoyed and said, 'Absolutely not,'" Maxwell tweeted.