What constitutes an emergency?

I had trouble with my computer tonight.  I won't go into the annoying gory details, but I didn't get to bed until 12:28 PM.  I lay there utterly wide awake for almost an hour and I couldn't stand it.  I turned and thrashed and sweated and tossed and finally got back up.  I was bored out of my gourd and restless.  I couldn't stand lying there.

I had no coffee or stimulants today, no chocolate, tea, cola, peppermint and only the tiniest dusting of ginger on the supper's stirfry.  And the only thing I ate that is on my possible danger list is about 1/4 of a banana.  But I am utterly wide awake.

Now I have a choice:  stay up until I feel tired later or drop from exhaustion or take a sleeping pill, an Ambien CR.  I'm only supposed to take them in an emergency, but what constitutes an emergency?  Sitting up all night tired and wired and wasting time better spent sleeping so I can hopefully have a more productive day tomorrow?  Once I am up past bedtime one night like this, it throws my whole schedule and my productivity to the winds for days before I get back on schedule.  Is that an emergency?  What's an emergency?

I hate not being able to sleep!