Problems with processing light?!

I think something is wrong with my eyes, or the way my brain processes images in certain lighting. I play tennis, and I've noticed that whenever I play indoors I feel almost as if I'm not there, as if I'm in a dream. The lighting seems to slow down my reaction time, which is affecting my tennis playing. My mom said that my cousin had a problem like this too, and it sometimes gives her seizures. I've had a CT scan or whatever, so I know I don't have seizures. I'm just curious though about what my problem is, and if it can be fixed. If anyone could help me out, I'd greatly appreciate it!