Sleep (2023), originally titled Jam, is a masterfully tense Korean horror-thriller that transforms a common domestic concern into a gripping psychological nightmare. The film follows Hyun-su and Soo-jin, a young expectant couple whose lives unravel when Hyun-su begins exhibiting violent and bizarre sleepwalking behaviors. As his nocturnal episodes grow increasingly dangerous, Soo-jin must race against time to uncover the terrifying truth behind his condition before it destroys their family.

Director Jason Yu demonstrates remarkable control over atmosphere, building dread through subtle sound design and claustrophobic framing that makes their apartment feel like a prison. The performances are exceptional, particularly Jung Yu-mi as the determined, increasingly desperate wife, and Lee Sun-kyun as the husband whose gentle daytime persona contrasts horrifically with his sleeping self. The film expertly balances genuine horror with emotional depth, exploring themes of marital trust, parental anxiety, and the fear of the unknown within someone you love.

With its 95-minute runtime, Sleep delivers relentless tension without overstaying its welcome, earning its 6.6 IMDb rating through smart execution rather than cheap scares. The Korean horror tradition of blending supernatural unease with real-world trauma is on full display here. Viewers should watch Sleep for its intelligent script, superb acting, and the way it finds profound horror in the vulnerability of sleep—the one place we're supposed to feel safe. It's a standout thriller that will keep you questioning what happens after the lights go out.