Sound Asleep lets you set your favorite player, so that it closes after you fall asleep.
Technically speaking, Sound Asleep enables you to set how long you want it to play your favorite music until it closes.
You can also choose whether Sound Asleep to shut down your computer or just to quit the app when it finishes the playlists.
NOTE: Sound Asleep can only be downloaded via the Mac App Store (the download link redirects you to its App Store page). To purchase/ download applications via the App Store an Apple account is required.