I always like to wear glasses when running. When it's bright out, I like to keep the sun out of my eyes. And when it's not bright out, I like to keep the bugs out of my eyes (as well as snow, rain, wind, dust, goose feathers, etc.) Normally I just grab whichever glasses are suitable for the current light conditions when I go out to run. But I've been doing a lot of trail running lately on fairly gnarly trails, and I need good visibility when I'm in the deep shade of a forest running on a trail with a bunch of tree roots and rocks sticking up out of it. But I also want protection from the sun when I'm on sections of trail that are out in the sun.
Are there any glasses that would be suitable for running that would work in both bright sunlight and in the middle of the night? I believe there are prescription glasses that are supposed to adjust to the light, but I'm not sure if there are non-prescription versions that would be good for running. I know most people probably just run without glasses at night, but surely there are some ultra runners out there who like to keep the bugs out of their eyes at night. Do they carry two pairs of glasses or one pair of glasses two sets of lenses that they change out or have one pair that can work during the day and night?