I work in a dedicated room in my house (remote developer). During the day I don’t really need to turn the lights on—windows and a skylight. The sun sets and sometimes I really just don’t notice. My wife will come in at some point and scold me for working in the dark, claiming it’s bad for my eyes (as if staring at a screen all day isn’t already).

I actually rather enjoy that rather not-subtle marker of the passage of time and how entrancing “the zone” can be such that I fail to even notice that.