Asian and Australian Players tend to have early morning fixtures, European and African players tend to have afternoon fixtures and North and South American Players tend to have evening fixtures.
I'm playing in Belgium, CET, and my games are mostly between 20:00 and 23:00 (I like it so I'm not complaining) while my friends who also play in Belgium always play at around 10:00.
Does this anything to do with the time they singed up?