It's always dark.

[Chrsitin]

Why can't players select the time of day they wish to play in?? It's always dark. I can't see surroundings, adversaries, or anything else. And it's not a monitor issue. Just give us the ability to specify game times, please.

[Bebekurenai]

An ingame day corresponds to 70 irl minutes. You hace plenty day/night cycles throughout the day. Or do you mean the HW lighting theme? You can control that in the system option by rising the character lighting. I have it maxed since I disliked the dark theme that came with HW and everything looks just bright and gorgeous.

[Niwashi]

Try turning up either Character Lighting, as Bebekurenai mentioned, or your gamma settings, or both. The former lights up the area immediately around your character (and I think is found in Character Configuration). The later lights up the entire game, including distant scenery, and is found under System Configuration.

(Overdoing the gamma settings can sometimes produce a washed out look, but it's better than everything being so dark that you can't see the environment.)

[Atoli]

Also, a lot of things are linked to the ingame time, so allowing the players to decide on it themselves would pose a HUGE problem
Sorry, but that's not gonna happen. Maybe you've just been a bit unlucky and have only logged on for a short while everyday while it was nighttime ingame so far?
Try the suggestions above to help see better during nighttime, and get online a bit earlier/later/longer or something if during the 20 min you are online it is always night.