A gentleman called Dominic Szablewski from PhobosLab has plotted his sleep pattern over the past 9 years – by analysing when his computer was connected to the web.
“For the last ten years or so, I used to turn on my PC when I came home from school or work and shut it down again right before I went to bed. So most of the time when my PC is running, I’m awake. I’ve also been idling in IRC for as long as I had Internet – when my PC is running, so is my IRC client.”

Via datavisualisation.ch. Read more here.
You can, of course, check out the state of your own sleep (including an analysis of any insomnia you might be suffering) by taking 5 minutes to complete our Great British Sleep Survey.