I woke up and was about to go to the bathroom, but discovered that my glasses are missing. I've been unable to find them, they do not appear to be anywhere near my bed or nightstand (the latter being where I left put them). I had to put on an older pair I kept as a backup.
Incidentally, their frames are more comfortable than the ones on my current glasses.
When I went back to bed I found my glasses. Apparently I had fallen asleep with them on and they slipped off during the night.