I was able to get a couple Data Explorer queries from Question and answer activity on StackExchange: Interactive and customized edition on Meta Stack Exchange. I chose the query Best time to ask questions on StackExchange: Get answer faster, rather than Best time to ask questions on StackExchange: More likely to get an answer, as the chances of a question that doesn't get closed not being answered are about as low as . . . well, something improbable.
Anyway, I switched the site to Worldbuilding Stack Exchange and the inputs to
All = 1
(all users)
Frequency = 1
(Gets data for the average day)
MaxTimeDiff = 1440
(Data ranges over the course of 1,440 minutes, i.e. one day)
UserID = 1
(all users; redundant since All = 1
)
Here's the graph I got:

As you can see, the shortest answer time - the lowest point on the graph - is approximately 13:00 UTC. At this point:
- East Asia and Australia are in or entering the night.
- Africa, Europe, and the Middle East are at midday to afternoon - approaching teatime, in fact.
- South America is already well into the morning, possibly finishing off an early cup of coffee.
- North America is rubbing its eyes, getting out of bed, and possibly leaving the house.
- Antarctica is doing its own thing entirely.
This might give you a decent idea of the demographics of Worldbuilding users, interestingly enough.
The worst time to get an answer to a question is right around 0:00 UTC, which is, by a strange coincidence, right about now.