Sleep spends its first act as a marriage comedy with a strange tic — a husband who talks, eats, and occasionally attacks in his sleep — and slowly lets the tic take over the whole relationship. Jason Yu, making his feature debut, structures the film almost like a stage play in three rooms: the bedroom where the trouble starts, the living room where the couple tries increasingly desperate fixes, and finally the apartment itself, sealed off and taped over like a crime scene the wife is building around her own husband. The film never fully settles into one genre — is this a psychological drama about a marriage breaking down, or a horror movie about possession — and that ambiguity is the entire point.
Jung Yu-mi carries most of the film's back half as Soo-jin, a wife whose love for her husband curdles into obsessive vigilance, taping notes to the walls, installing cameras, refusing sleep herself to monitor his; her performance tracks a woman's rational problem-solving sliding into something closer to superstition without losing the audience's sympathy. Lee Sun-kyun, the Parasite actor whose death shortly after the film's Korean release cast a somber shadow over its international rollout, plays the husband with an unsettling blankness during the sleepwalking scenes that contrasts sharply with his warmth when awake, making it difficult to know which version of him to trust.
A husband's sleepwalking turns a marriage into a hostage situation neither spouse can admit they're part of.
What makes Sleep more than a gimmick movie is how patiently it earns its dread through domestic detail rather than jump scares — duct tape on doorframes, a growing wall of superstitious research, a home slowly transformed into a padded cell by two people who both believe they're the reasonable one. It's a smaller, stranger film than most horror-thrillers get made these days, closer in spirit to Rosemary's Baby's slow-building paranoia than to anything jump-scare-driven, and it trusts its two leads to carry tension through conversation rather than special effects.
Sleep is the feature writing and directing debut of Jason Yu, a former assistant director for Bong Joon-ho on Okja, and the film reflects that mentorship in its tonal control and slow-building dread. It premiered in the Critics' Week sidebar at the 2023 Cannes Film Festival before opening in South Korea that September, where it became one of the country's higher-grossing domestic releases of the year. The film was produced by Lewis Pictures on a modest budget and shot largely within a single apartment set, a constraint Yu has said pushed him toward tighter, more theatrical staging. It received a U.S. theatrical and digital release in September 2024.
Sleep drew strong reviews internationally for its blend of horror, dark comedy, and marital drama, with many critics highlighting Jung Yu-mi's performance and Yu's confident control of tone as a first-time director. The film's reception was complicated by the death of co-star Lee Sun-kyun in December 2023, months after Sleep's Korean release, following a widely publicized drug investigation; his death made Sleep one of his final completed film roles and added unintended weight to later international screenings. Critics have since cited the film as one of the strongest Korean genre debuts of the decade so far.
