Hmmm, well I don't wish to alarm you but I
would get to an ophthalmologist tomorrow,
as you could have an impending retinal
detachment and if that happens, you don't
get another chance! Rainbow coloured
halos are usually a sign that you need
urgent attention!
Edit: Okay I have checked a few sites and
it seems halos can occasionally be caused
by overtired, overused eyes so maybe
you're okay

but still, better to err on the safe side!
