Deep Sleep uses binaural beats and solfeggio frequencies tracks to help you fall into a deep sleep quickly. All you have to do is switch on the app and press the play button the app will select a song randomly for you from the existing list of songs and you then have to select the timer for the time till which you want to play the song - that's it.
Ideally - use it everyday at night for a deep sleep and based on the selected timer the song will stop playing.