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 lives unravel when Hyun-su begins exhibiting violent and bizarre sleepwalking episodes. As his nocturnal behavior escalates from strange murmurs to potentially dangerous actions, Soo-jin is thrust into a desperate race against time to diagnose and stop the condition before it destroys their family.

Director Jason Yu delivers a debut feature of remarkable restraint and escalating dread, using the confined setting of the couple's apartment to amplify the claustrophobic horror. The performances are the film's bedrock. Lee Sun-kyun brings a haunting duality to Hyun-su, while Jung Yu-mi is utterly compelling as the resilient, resourceful wife whose love is tested by primal fear. The film expertly blends psychological mystery with genuine jump-scares, asking unsettling questions about the subconscious mind.

Viewers should watch Sleep for its intelligent approach to horror. It's less about supernatural monsters and more about the horror of losing trust in the person you love most, and the vulnerability of sleep itself. With its sharp pacing, atmospheric tension, and superb central performances, Sleep is a standout in the modern horror genre and a must-watch for fans of psychological thrillers and Korean cinema alike.