Yankee Candle Sleep Diffuser Refills create a relaxing atmosphere for great sleep! Select from three fragrances, each specially blended with ingredients known for their calming properties, such as lavender, eucalyptus and cedarwood. Mess-free refill bottles make using the Sleep Diffuser a dream! Simply insert the refill directly into the diffuser - there’s no water to add - and enjoy 30 nights of relaxing fragrance*. Set the diffuser’s timer for two, four, or eight hours of soothing ambiance, at the fragrance intensity you find the most restful. *Based on 8 hours of nightly use on lowest intensity setting