Sleep Tight (Spanish: Mientras duermes, "While You Sleep") is a Spanish horror thriller film directed by Jaume Balagueró and was written by Alberto Marini. Apartment concierge Cesar (Luis Tosar) is a miserable person who believes he was born without the ability to be happy. As a result, he decides his mission is to make life hell for everyone around him. A majority of the tenants are easy to agitate, but Clara (Marta Etura) proves to be harder than the most. So Cesar goes to creepy extremes to make this young woman mentally break down.