Why Should I?

Close-ended question, meaning there's one right answer and I'm not sure what it is.

Has anyone rubbed their eyes really hard, or went from a really dark room into really bright light, and their eyes started doing the psychedelic, spastic, swirling star things where patterns and blue dots take up their vision? (I know I can't be the only one who has this happen.)

Anyways, that's not really the question. The question is- why? Why do we see blue stars when we get too dizzy? Why does my brain start to do the psychedelic swirl if I rub my eyes too hard? What's going on?

And if nobody really likes those questions, here's an alternative optional one: Does looking into a bright light help you sneeze?
more on bright lights and sneezes here: http://www.scientificamerican.com/article/why-does-bright-light-cau/

Notes

I'm feeling very scientifically questioning today. Cuter questions will be posted tomorrow; I was just very curious at the moment