Despite being able to sleep anywhere other than at bedtime (fell asleep standing up on a train going across central Europe once - propped up by two on-leave soldiers on either side) I used to have trouble getting to sleep in bed at night.
Think boring - names alphabetically - Andrew, Bill, Colin, David... etc - works equally well with films, book titles, countries towns...
Nowadays, if I am having trouble nodding off I usually don't get beyond G.
A clear concience helps, of course!!
Jim Carroll