Skarsgard, 27, played the dreadful clown in the movie, which was based on Stephen King's 1986 novel of the same name.
"I was home, done with the movie, and I started having very strange and vivid Pennywise dreams. Every night, he came and visited," Skarsgard told Entertainment Weekly.
"It was in the shape of either me dealing with him, sort of Pennywise as a separate entity of me, and then also me as Pennywise in circumstances that I didn't appreciate. Like, I'm Pennywise and I'm really upset that I'm out in public and people are looking at me," he added.
However, Skarsgard does not think that his dreams have a deeper meaning.
"This was a process of letting go of the monster. It was amazing. It's a daunting but exciting thing to sort of revisit him again," he added.