Not being able to sleep cause you're excited about something.

Hmm, usually games with a good story and in the middle of it, you never want to stop. One example from before was Tales of the Abyss, that game was long for one disc, and I remember every time I get through one part of it, the next destination or plot would be a I-must-know-what-happens-next that sleep has become irrelevant.

Of course, another example is, back in the day... Dangerous Valley II, Red Drakes, hunting for 12mil Steely.