exactly the same happened to my 2 parrots. i put a sheet of newspaper on top of the drip tray blocking some of the light, then gradually removed it over the course of the day. now they are fine!
hiya
just joined this site, my name is helen and i work at pets at home in bristol (boo - i know you guys all hate us!) but you all seem like a friendly bunch so thought id join, maybe meet some new people.
anyway, here is my tank;