Up until the end of 2006 I worked on a 24 hour rotating roster, and would stay up all night prior to a grave shift the next night (so I could sleep through the day). I fell asleep playing a heap of games when doing that, but most consistently it was Lumines Live. I'd start going insane past 3 AM and Lumines was the only game I could concentrate on, but it was so hypnotically paced it was easy to fall asleep to. I remember a bunch of times falling asleep with a blank screen, and waking up just as the last piece fell into place, creating a tower that killed me, heh.