I have never fallen sleep at work, but my husband does almost every single work day. Luckily he doesn't get in trouble. His office mate just wakes him up when necessary. My husband has always had issues with nodding off in public places. I wouldn't go so far as to say he has narcolepsy, but close.

I hope you can let that day roll off your back. Being able to do so with embarrassments, and other things, has served me quite well in life. If ever you do get in trouble, if you think medications or your bipolar are the culprit, you can say that even not going into specifics.