“It’s absolutely brutal,” former Vermont Gov. Howard Dean told NPR. Dean led the Democratic field for much of the 2004 primary before his campaign collapsed after losing the Iowa caucuses. His speech that night went viral for what sounded like Dean yelling into a microphone in a loud and crowded room.

“You see the worst side of humanity by most of the people who are involved in it,” Dean added.

Dean said he anticipated “the meanness” before he entered the race, but he said he was surprised by the campaign’s physical demands.

“You’re basically getting four-and-a-half hours of sleep for two years,” said Dean, a medical doctor. “It’s very tough on your health. I eat when I’m tired, so I probably gained 20, 25 pounds.”