An old mentor gave me advice that I think has done me very well: only use your bed for sleep and sex.

Don't read in bed. Don't listen to anything that requires brainpower (spoken word, for instance). Turn off the light and go to sleep. If you're not really ready to sleep, and feel the need to do a little reading, surfing, whatever, get out of bed and do it elsewhere. So I don't even bring my phone/tablet/whatever into the bedroom at all.

The idea is to program your brain to associate bed with sleep, so going to bed is a stronger cue that it's sleepytime.