A few times a year my lower eyelid starts to twitch. It is annoying, but not painful in any way. It is happening now and I looked up the different reasons it can occur:
Computer eye strain
Yup, yup, yeah, uh huh, right. All of the above. Boozy wedding party in LA last weekend, no sleep, running a startup, drinking lots of coffee.
I often do not notice when I am stressed out and overtaxed, so I am glad my body has developed relatively harmless way of letting me know to take it easy.