Sansevierias are one of the best plants when it comes to air purification because they take in toxins and give off oxygen. They're great plants for the bedroom because they release them at night. Don't expect 1 plant to purify your whole bedroom though – only the air immediately around it.
Care
Sansevieria likes to dry out completely between waterings. The most common mistake made with these plants is overwatering. Even if your plant is placed in ample bright indirect light, you won't need to water it more than once every 10 days (at most) during the growing season.