So does this colleague suddenly have to work 9-5

Worst of all, he sees a bit of daylight on the sunrise commute home. Yet I as a +10 would never see the sun.

Everyone who works a daylight job would work a daylight job with Universal Time. We exist under Universal Time right now, and yet you (and the majority of other people in the world) work during the day. Nothing would change.

Everyone would work whatever part of the day they work right now, except the numbers would change. And you'd have to learn what numbers mean "get up", "lunch", "dinner", and "sleep" because they won't be what you're used to.

The current clock numbers are entirely arbitrary. (And they repeat!) When you were a kid, you had to learn what the hours meant relative to what part of the day it was. Under universal time, you would simply relearn that. Children learning it now would never know the difference. They would think local time is weird.

I don't understand why every time this conversation comes up, there are always people who think that it means you'd have to change when you sleep, live, and work relative to the sun. I just don't get it. It just seems like such an odd conclusion to me.