Sean Penn Visits 'Late Show' While on Ambien, Explains Why He's Over Acting

Stephen Colbert "inherited" some of Sean Penn's Ambien hangover when the actor made an appearance on The Late Show Monday night.

"You've inherited a little bit of the Ambien I had to take to get to sleep after a red-eye last night," the sleepy-eyed star told the late-night host while relaxing on his couch.

"So, in other words, you're still a little bit on the Ambien train right now?" Colbert asked, to which Penn responded, with a smile, "A little bit."

Colbert riffed with the star about how he could decipher "Sean Penn on Ambien" from "Sean Penn not on Ambien" and the first giveaway was when Penn took out a cigarette and lit up. Colbert was prepared with an ashtray: "I thought you might."

He then challenged Penn to bring more energy to the interview than his Friday guest, Jimmy Carter, who is 93.

Penn was hitting the late-night circuit to promote his debut book, Trump-era satire Bob Honey Who Just Do Stuff: A Novel. The plot centers on a septic tank salesman-turned-assassin who kills old people with a wooden mallet. The novel's protagonist also sends a threatening letter to a fictional president, something that could allude to the activist's public distaste for Trump.

Colbert jokingly asked Penn if he was on ayahuasca tea while writing the tome, and Penn admitted that the idea sprung from him thinking the whole country was on a psychedelic trip. "I wanted to do something in fiction that would be inclusive of everybody," he said, referencing the country's political divisions.

While smoking his second cigarette, Penn admitted that the book was a way for him to vent. Referencing the recent Florida shooting, he praised the instant mobilization from the Parkland students as a wave of change and something that might inspire him to write a "less dystopian" book next time.

"It's all about where you engage in an expression creatively, one way or another, and the greatest thing that an actor can bring to the party is to play well with others, it's the collaboration. I increasingly don't play well with others," the Oscar winner explained of making the jump to author. "So it becomes less enjoyable. I love that process when I love it, but I'm not loving it anymore and that's why I finally came around to writing a novel because I didn't have collaborators — I was never disappointed with me."

Penn also cited the overabundance of entertainment content as why he is turned off from acting. "The girl I fell in love with was going into a movie theater in the dark with strangers and seeing something that might last forever," he said, "and now there is so much content, I can't keep track of it and nothing seems special."

Colbert replied, "So, you're blaming this on Netflix?"

Watch the interview below.