What is something you missed because you took a short nap (or what you THOUGHT would be a short nap)?

I missed my time of arrival at work couple of times when I was on call. I would get a two hours notice by phone at midnight for example, to appear on the job at 2am. It only takes about 15 minutes to drive to work and I feel very drowsey so I thought I would just nod off for about an hour.  Ring ring ring.. "oh shit! I'll be there SAP!"

That was forgivable once or twice but we were advised to get proper rest during the day in anticipation of being called at any time. I was a brakeman for CN Rail.

Usually the end of a TV show or movie I was watching. If I think I might fall asleep, I record it.

A TV show usually.  I'm not a power napper, so I usually know that if I make the decision to nap, it will be for 1-1.5 hours.