Sleep Tight

• The Spanish title is "Mientras Duermes" ("While You Sleep"); "Sleep Tight" is the English-language title used by Filmax, the Barcelona studio that produced the film and also backed Balagueró's [REC] franchise.
• Interior apartment scenes were shot on a reconstructed set at the Parc Audiovisual de Catalunya studios in Terrassa, while the building's lobby and elevator sequences were filmed in a real Barcelona apartment building (Casa Argelich, on Rambla de Catalunya).
• The film landed only one Goya Award nomination (Best Actor, Luis Tosar) but dominated Spain's Gaudí Awards instead, winning 6 of its 15 nominations — including Best Film in a Non-Catalan Language, Best Director for Balagueró, and Best Actor for Tosar.
• At the 44th Sitges Film Festival in October 2011, Balagueró received the festival's honorary Máquina del Tiempo (Time Machine) career-tribute award, with Sleep Tight screening out of competition rather than winning a competitive prize.
• The film later won the Silver Hugo in the After Dark Competition at the 2012 Chicago International Film Festival.

Cesar's fixation on Clara isn't sexual — it's ontological. He needs her unhappy because her happiness proves his suffering is optional, not inevitable. Clara functions as a proxy for a world that won't acknowledge him, and his violations are structured to force attention without granting satisfaction.

The film operates as a real-estate horror story. Cesar's true power isn't psychopathy — it's the building's architecture. The concierge role gives him institutional cover, and Balagueró frames every doorway, vent, and crawlspace as a vulnerability. The terror isn't that a monster exists; it's that the building was designed to let him move unseen.

The ending's real twist isn't a confrontation — it's the letter. Clara moves on believing she's finally free, pregnant with what she doesn't yet know is Cesar's child, when he mails her a note designed to make sure she can never look at that child without thinking of him. It reframes the whole film: Cesar was never trying to break Clara once. He engineered a life sentence, and got away clean.

Cesar (Luis Tosar) is the concierge of a Barcelona apartment building — the pleasant face tenants trust with their keys and complaints by day. He's convinced he was born without the capacity for happiness, so he's dedicated himself to spreading misery instead. By night he lets himself into apartment 5B, chloroforms resident Clara (Marta Etura) into a deep sleep, and quietly dismantles her life — lacing her cosmetics with allergens, planting insects in her apartment, sabotaging her relationships. He doesn't want her dead. He wants her broken, and he's patient about it. When Clara's boyfriend Marcos starts staying over, Cesar's routine gets riskier and his methods escalate. Balagueró flips the haunted-house formula: the monster doesn't break in, he already has the keys — and the film's real horror is that this isn't a story where he gets caught. Cesar's campaign ends in tragedy for Clara and a clean getaway for him, walking into a new job with his pattern fully intact.