I think overstimulation can cause a person to have a little adrenaline in their system that can then keep you up.

When I used to work a lot of long hours, like 18 hour days, it would be difficult to fall asleep because of all the adrenaline running through my system - even if I was very tired. It's a typical cycle for people in my career of live theatre and live events because we tend to work long hours late into the night on a regular basis.

Some of the tips I have found to help avoid insomnia by googling it in the past are:

-don't do anything in your bed room except sleep and have sex
-if you've been trying to fall sleep and can't, get up and do something somewhere else and then try to go back to sleep later
-try to wak up at the same time every day, this will eventually get your biorhythm on a regular sleeping pattern
-a regular sleeping pattern can help to alleviate insomnia
-avoid caffeine after 2p
-avoid alcohol as a method to help fall asleep, it messes with the REM cycle
-exercise can help too
-anxiety increases the chances of insomnia

I had bad insomnia for a while in the first year or more after the accident I was in, but I'm finally sleeping pretty well most days.