Billie Eilish spoke out about her experiences living with Tourette Syndrome in a recent interview with David Letterman on Season 4 of his Netflix show, My Next Guest Needs No Introduction With David Letterman.

The 20-year-old "Happier Than Ever" singer isn't shy about opening up about her struggles with mental health or body image, but Letterman was able to tear down a wall with Eilish, who finally opened up about the condition she was diagnosed with when she was 11 years old that she rarely speaks about, according to Uproxx.

During the interview, a change in lighting on the set apparently caused a tic. "If you film me for long enough, you’re going to see lots of tics. I don’t care. It’s really weird, I haven’t talked about it at all. The most common way people react is they laugh, because they think that I’m trying to be funny. They think I’m (ticcing) as, like, a funny move … And I’m always left incredibly offended by that," Eilish said.

She added, "What’s funny is so many people have it that you would never know. A couple artists came forward and said 'I’ve actually always had Tourette’s.' And I’m not gonna out them, because they don’t want to talk about it, but that was really interesting to me. I was like, 'You do?! What?'"

Letterman told Eilish he "knows nothing about (Tourette's)," to which she replied, "I actually really love answering questions about it because it’s very, very interesting. And I am incredibly confused by it, and I don’t get it. These are things you would never notice if you’re just having a conversation with me, but for me, they’re very exhausting. It’s not like I like it, but it’s part of me. I have made friends with it. And so now, I’m pretty confident in it."