Setting a sleep timer
You can set iPod touch to stop playing music or videos after a period of time.
Set a sleep timer: From the Home screen choose Clock > Timer, then flick to set the number of
hours and minutes. Tap When Timer Ends and choose Sleep iPod, tap Set, then tap Start to start
the timer.
When the timer ends, iPod touch stops playing music or video, closes any other open app, and
then locks itself.