I ride at all different times of day. I want a new pair of goggles, and I'd really like a mirrored pair. They look really nice, and it would be great to screen out some of those bright rays. But is it still okay to use mirrored goggles when riding in the dark? Will it make that much of a difference?
It really depends on what type of lens you get. there are lots of different levels of mirrored lenses that let in more or less light.
I personally own the Oakley Airbrake goggles and they came with two lenses (fire iridium for the day, and a high intensity yellow with a bit of blue iridium for overcast/night). They both have a mirrored effect, but its much greater on the fire lens.
IMHO, its always best to have two lenses because one really can't cover you in all situations. There are a TON of models out now from different brands with quick change ability too!
generally speaking the color that is getting reflected is the color not going through the lens, so mirrored lens works great when its bright outside. at night, I think you will have trouble seeing stuff. get something like orange clear.