I think perfection is probably somewhere between dark and light themes. Light can frequently be too bright where it feels like you're looking into the sun. And dark can be like working in literally the dark, and it's sometimes too difficult to see the boundaries between objects. I think it would be cool if we had a sliding scale, where you can pick from several brightness levels.

Maybe you've been using themes with too much contrast ? I mean, I can't work on a light theme for any extended period of time, but most dark themes are too stark and eye searing for me, so that may be your case too?