Sleepless nights

Last night was to say the least restless, I didnt actually get to sleep until around 05.00 this morning..

So Ive only had aproximately 4 hrs sleep, still I feel wide awake.

I dont have these nights very often, I love to sleep and can fall asleep in a noisy nightclub if I wanted to (and I have done, however it might also have been helped by the amount of alcohol that was in my body at the time)

So what was it that was occupying my thoughts last night? What made it impossible for me to shut my eyes and get some rest?
Why cant our brains "shut off" but sometimes - or quite often for some people - work overtime going over and over the days events?

I can understand people who have very exciting lives were intresting things happen all the time and they obviously need to relive all the magic again.
I would...

Today will be spent doing laundry and relaxing, I might catch up on some sleep or my body might decide that ive had enough and wont get to rest until tonight