Lee Sun-kyun and Jung Yu-mi in Sleep (Magnet Releasing)

Bringing a child into the world can be stressful. A couple of recent films (Ruby Baby, Huesera: The Bone Woman) have explored the effects of the stress of conceiving children. In Sleep, there’s a bit of a twist on the theme as a newlywed and father-to-be acts out while sleepwalking and does not remember his actions when he awakens—and these actions are pretty terrifying.

Hyun-su (the late Lee Sun-kyun of Parasite) and Soo-ji (Jung Yu-mi) are a happily married couple expecting their first child. Hyun-su, a struggling actor, occasionally gets walk-on roles, but he’s pretty much relegated to background work. The expecting Soo-ji, an estate agent, waves away his offer of finding a more permanent, financially stable source of income, believing he is destined to make it. They have a sweet little Pomeranian that they clearly cherish, and their apartment is large and modern, with a wooden carved sign hanging in the living room, “Together We Can Overcome Anything.”

Their perfect life is interrupted when Soo-ji wakes up to find Hyun-su sitting on the edge of the bed. When Soo-ji asks what’s wrong, Hyun-su simply responds, “Someone’s inside,” and then falls back asleep. He has no memory of it the next morning. As disturbing as that is, future episodes involve him sleepwalking, eating raw meat, and trying to jump out a window. Understandably, Soo-ji becomes concerned.

After a visit with a doctor, the couple take precautions, and Soo-ji zips Hyun-su in a sleeping bag and locks him in a room. But he somehow breaks free during the night, and Soo-ji is now too anxious for her husband’s safety to sleep. Now, as the father of two, one thing I and other new parents have learned is that one adult has to be rested and lucid. Suffice it to say, that does not happen here. Add to that Soo-ji’s domineering mother, who believes the culprit is a ghost, and the movie posits a classic question: Is this a scientific, psychological, or supernatural setup? The film juggles all three options deftly before choosing one and going for broke.

Writer/director Jason Yu peppers the mayhem with humor that breaks the tension he deliberately builds only to construct again. It’s like he is playing Jenga against himself and really enjoying it. And make no mistake, Sleep is funny. Soo-ji’s reaction when a doctor says Hyun-su’s condition is incurable is priceless. Yet through all the humor and horror, the chemistry and demonstrable love between Hyun-su and Soo-ji remain palpable. Usually, in horror, the characters’ flaws are exploited and a perfect facade cracks. Here the conflict reinforces the couple’s attachment and love for each other. Hence the constant return to the sign that Hyun-su made. They go through a lot to get there, and there is some damage, physical and psychological (not necessarily just to themselves) along the way. But isn’t that the way with any strong relationship?