Sleep (2023), originally titled Jam, is a masterfully tense Korean horror-thriller that explores the terrifying breakdown of domestic safety. The film follows Hyun-su and Soo-jin, a young expecting couple whose life unravels when Hyun-su develops violent and bizarre sleepwalking episodes. As his nocturnal actions grow increasingly dangerous, Soo-jin must become a detective in her own home, fighting to protect her unborn child and solve the horrifying mystery behind her husband's condition before it's too late.

Director Jason Yu, a protégé of Bong Joon-ho, delivers a debut of remarkable control, building dread through domestic spaces turned sinister. The performances are utterly compelling; Lee Sun-kyun brings a haunting duality to Hyun-su, while Jung Yu-mi is phenomenal as the resilient, increasingly desperate Soo-jin. Their chemistry makes the horror deeply personal.

More than a simple monster movie, Sleep is a psychological exploration of trust, parenthood, and the fear of the person you love most. The 95-minute runtime is a relentless, expertly paced descent into anxiety. With its sharp script, atmospheric direction, and standout performances, this is a must-watch for fans of intelligent, character-driven horror. It proves why Korean cinema remains at the forefront of the genre.