I know we gamers are kind of half-owl-half-man kinds, but my perception is that questions asked at night get less visibility than questions asked by day.
Is there any data on meta that supports this perception ?
The most common hour to ask questions is 2000-2059 GMT. The other busy times are mid-afternoon to late evening GMT: 1900, 2100, 1700, 1800, etc. Not many questions show up between 0500 and 0959, so if you want question visibility, comparatively speaking, that's a good time to do it.
So in that sense, yes, GMT evening questions get less visibility than GMT morning questions because they have more competition.
Surprisingly, answers tend to appear before questions ... perhaps we're more likely to start a Gaming.SE session by answering existing questions before we ask our own. The most common hour to answer questions is also 2000-2059 GMT, followed by 1900, 1700, 1600, and 1800. 0500 to 1059 is the "dead zone" for answering questions.
If you want to get more specific, people love to ask questions on Wednesdays from 1900 to 2159 GMT: those are the top three answers on the board, as they say on TV. Saturday and Sunday mornings are devoted to not asking questions: 0500 to 0659 are good times to ask a question and be sure it will not have much company, although for some reason, 0900 to 0959 on Sunday is the best. (That does coincide with early NFL games, but that's a coincidence, I'm sure: the NFL regular season is roughly one-third of the calendar year, and I'd guess only a small percentage of Gaming.SE visitors are also NFL fans.)
1900 to 2159 GMT on Wednesdays are also happy hour for answering questions, so if you can't get your question some "alone time", ask on Wednesday evenings if you're in Europe or Wednesday afternoons in North America. Saturday and Sunday mornings, GMT, are times when people are not answering questions ... so maybe you don't want to ask a question then!
It was done for stackoverflow here.
But anyway, you'd need to define "night" as we are pretty international here