If you ever have difficulty getting [back] to sleep, you may find that reading a book or listening to music for a while will make you sleepy.
That's OK if you sleep alone, but turning on a light to read a book or cranking up the volume on your MP3 player at 2am may make you very unpopular if you share your bed.
But maybe you can get away with listening via a pair of headphones, if you keep the volume turned down low on your radio.