iPod nano (6th generation): Music stops when display turns off
Sometimes the music you are listening to may quit playing when the display on your iPod nano (6th generation) goes dim.
Verify that you have firmly connected the headphones to the headphone jack on your iPod nano. The cable should be flush against the iPod with no visible gap.
The image on the left below is an example of an iPod nano (6th generation) with a partially inserted headphone cable. On the right is an iPod nano with the headphone cable fully inserted and flush.