Pretty much anyone who decided to work for a company where the agreed upon hours are from X to Y. You can complain about it being unnatural all you want, but if

Pretty much anyone who decided to work for a company where the agreed upon hours are from X to Y. You can complain about it being unnatural all you want, but if those are the hours that you agreed to, then you're obligated to conform to the schedule. If you don't like it, work remotely for a company whose normal business hours fit your schedule. Being an adult is not necessarily about conforming. It's more about sticking to your obligations. Even if your word means nothing to you on a personal level, others are probably depending on you to come through.