Is it normal that i sometimes keep my right eye closed?

This is a weird question, but like, I spend most of my day on my computer and usually when the night comes and after being a bit stressed out or tired I'll just close my right eye and keep it closed, usually without noticing, and I can keep it closed for hours, for apparently no reason.

I don't know if it's out of being tired, or because of the bright lights or what, but it happens regularly and I just close it and keeping it open takes a bit of an effort.