There are three versions of the sleep mask:
Use your own brainwaves to get the rest you need. Includes 5 sleep songs, each 20 minutes long, corresponding to a person falling asleep.
Learn to control your dreams! Also includes 1 sleep song to help get the rest you need.
Use your own brainwaves to meditate. Includes 5 meditation songs, corresponding to a person having a really nice 15-minute meditation.