Even if you haven’t seen Sleep yet, if you’re a fan of Korean cinema, you’ve probably ired some of Jason Yu’s handiwork. Before breaking out with his feature debut, Yu took an alternative path through the South Korean film industry: after the traditional first step of assisting an established filmmaker—in this case, the legendary Bong Joon-ho, who Yu credits as a major influence—Yu began working as a translator, creating English subtitles for Korean films like Lee Chang-dong’s Burning.

Now, Yu is taking his place as a filmmaker in his own right with Sleep, which premiered as part of Cannes’ Critics Week in 2023 before making its way through the North American festival circuit that fall. Meanwhile, the picture was already tearing up the box office in South Korea, where it sold a million tickets within two weeks of its debut. At last, it’s set to bow in US theaters.

Starring Jung Yu-mi and Lee Sun-kyun as young parents Soo-jin and Hyun-su, Sleep ties together comedy, suspense, and psychological and supernatural horror as the couple is confronted with an unsettling dilemma: Hyun-su has been acting strange in the middle of the night, and doesn’t any of it the next morning.

Throughout the film, Yu keeps viewers on their toes through a skillful manipulation of tone. “You’re chuckling one moment and holding your breath the next, feeling like you’re descending into madness right along with them,” Sydney writes. Yu’s taste is similarly unpredictable: a self-professed rom-com superfan, the filmmaker immersed himself in horror before directing Sleep, and ended up with a film that no one knew how to market because they couldn’t figure out what genre it was.

Note: This interview took place before Lee Sun-kyun’s death on December 27, 2023, and the shock waves it sent through the Korean film industry.

What do you consider your primary form? Are you a director or writer first?
I’m [primarily] a director. I forced myself to become a writer to write my own screenplay, but I do like the process. I’m a shy person and I can’t mingle with people that well. With writing, you’re by yourself. Social anxiety isn’t there.

Are you into horror movies, or did you just want to tell this particular story?
At first, I wasn’t an incredible fan of genre films. I was more in the romantic-comedy camp. But the story dictated that [Sleep would] become a horror film. So after I wrote the screenplay, there was an intensive period of me devouring all the classics, [as well as] contemporary [horror] films. It was intense. But it was a great revelation, because I realized [I had] missed out on some great films, and I became a massive fan during that process. I can almost say it’s now my favorite genre.

Since Letterboxd is all about your life in film—what were some horror films that blew you away?
Even before that intensive period, I always came back to The Shining and Rosemary’s Baby. I never consciously used these films as references for my cast and crew. But looking back, it’s so obvious they’re in there.

As far as contemporary films. I really liked Barbarian. I thought it was a very suspenseful and funny movie. I also liked It Follows and It Comes at Night. Those were great. Lots of great Korean films as well—one called Svaha: The Sixth Finger, and another great Korean film called Possessed from Lee Yong-ju, who was an early student of Director Bong’s.

READ: JASON YU SHARES TEN FILMS THAT INFLUENCED SLEEP

I now want to know what kind of rom-coms you like.
The thing about a rom-com is, no matter how bad it is, I have such a soft spot for [the genre] that it’s going to be an automatic five stars for me. I really like Silver Linings Playbook. What the characters are going through is very intense, but there’s a layer of warmth and a comion the camera has that makes me feel like everything’s going to be okay. That’s the tone that I wish to mimic when I create my films. In Sleep, things get horrific, but I wanted that layer of warmth you have in Silver Linings Playbook.

I also really love The Apartment. And I’m not sure if you could classify it as a romantic comedy, but I also like Eternal Sunshine of the Spotless Mind. Also, the Working Title films are huge in Korea. Have you heard of About Time, starring Domhnall Gleeson?

That movie was big in Korea?
I think it did better in Korea than in the US! I also love Love Actually and old Hugh Grant films, Notting Hill in particular. When people ask me what sort of film I want to make next, I always say romantic comedy. People are like, “Forget about that. Stick with what you’re doing,” which is kind of a bummer.

Because I was on the cusp of marriage, I had a more romantic and hopeful view of what it could be. I wanted to show a couple who are best friends, who really love and each other, and throw them an external obstacle to see how they would overcome it as a unit.

While I was writing the screenplay [for Sleep], I was unemployed. I had nothing going for me. I only had a script and a pipe dream. There were times where I thought that maybe I should just give up and find a more realistic job—like Hyun-su in the movie, I felt irresponsible pursuing this career path. But it was my then-girlfriend, now wife, who was doing better financially and career-wise, who always stopped me from those kinds of thoughts. “You’re the best. You’re going to show the world.” That was always the attitude she had towards me and my goals and my dreams.

Did you give her the screenplay to read after you finished it?
Yes, it was almost like role-playing, because in certain situations I’d ask her, “What would you do here?” If there is realism, that’s where it came from. We inserted ourselves into the story, almost like a game. She really liked the screenplay—I couldn’t see the personal elements [yet], but she saw them right away and realized [the story] was more about marriage and love than horror.

My favorite thing is something you alluded to earlier—even when Sleep gets dark, you’re always on the verge of laughter. Anytime it’s funny, it could burst into horror. How do you create that tone?
It wasn’t intentional, but I think a lot of Korean directors do that. Director Bong does it really well. My favorite films are Bong Joon-ho films. I watch them compulsively. Just by absorbing all his films, there is a [tone] that I try to mimic. While I was [assisting on] Okja and doing a lot of translating for [him] in interviews, he was also asked about the mix of genres and tones a lot. What he said really stuck with me: he said he’s never really conscious of what genre he’s [working with]. Even when the film [is finished], he’s never really sure what genre it is. He lets the marketing team decide.

About shifting genres, he says that’s just art imitating life. Because in life, even when there’s a fun little party happening, you could always find an underlying sadness. And at a funeral, there are times where you have to hold your laughter.

The funeral scene in The Host is, to me, the quintessential example of what we’re talking about.
That’s what I was thinking as well. If you lead your characters to have true reactions to these absurd situations, it’s incredibly comedic, despite the high stakes and the horrific situations. I never intentionally tried to create a scene just for laughter, or have a funny line to get people to smile. It was just, “What would [these characters] do in this situation?” Sometimes, it’s so absurd that people laugh. My hope is that it’s not too absurd, or so outside the realm of possibility that people are thrown off by it.

Often when a movie gets tense, people will laugh just to relieve the tension.
It’s the best when that happens. I find myself laughing at disturbing scenes as well.

Can you give me an example?
The face scratching, or the dog scenes. I guess we were numb to the whole story. We had seen it too much to feel the visceral fear. But when it came out [in Korea], we were pleasantly surprised to find that a lot of people were terrified by the film—so much so, it deterred mainstream audiences from seeing it.

That’s interesting, because a lot of the exorcism elements happen off-screen. Why did you decide to approach those scenes that way?
I like stories that are like plays, with a three-act structure. Things happen between each act, and the audience has to figure it out. It’s almost like a puzzle. That gives me a lot of gratification as an audience member, so I try to replicate that.

On a more practical level, later on in the film, the whole apartment is covered in paper talismans.
The production design team did it. We had to be realistic and consider that, in the story, it was Soo-jin doing it herself in a limited amount of time. So we tried to replicate how much time she must have had and how much [she could do] in that time. It was much more than I thought a single person could do in twelve hours. If you watch [the film] closely, you see that near the entrance and in the living room, she’s very thorough. As she goes towards the kitchen, it’s much more sparse.

She’s getting tired.
And she’s running out of time. So she—I’m not sure the proper term for it in English—half-asses it. She’s more lazy with it, less thorough.

You broke that rule, too!
We broke both. The production company and the studios were hesitant, but they respected our vision and went along with it. In the end, they were happy.