You can choose from the default music included in the app - or you can choose any music from your iTunes. You can play different songs based on how sleep deprived you are, where if you sleep far less than your sleep goal then a different song will play compared to when you reach your sleep goal - motivating you to wake up when you need it most. You can also choose the vibrate to wake feature, where the phone vibrates you awake. This is a useful feature for light sleepers who are worried about waking their sleep partner.
You can choose from Proactive Sleep's default music, which can be played seemlessly throughout the entire night of sleep. If gradual wake is set to on then your ambient music will start playing 10 minutes before your wake up time, soothing you awake in the morning and preventing grogginess. Additionally, relaxation music that is proven to help with falling asleep is included as in-app purchases. This includes the Miracle SleepSystem, which was developed by a professional musical engineer, and the Progressive Muscle Relaxation Meditation, which was developed by a sleep clinician.