Too Long; Didn't Read
The notion that everybody works the same "8 hours" means that there would be people around the world who have to tolerate sleeping in the daylight and working in the dark year round. The biological clock evolved to want to be awake in the day in a sleep at night. If we were to get rid of it it really wouldn't be a big deal. It takes me literally 10 seconds to change my clocks when we switch our time. The reason for it is obsolete. It used to be to allow farmers more daylight time in the summer.