Re: temporary blind in one eye-?!
If you sleep with that eye pushing into the pillow or your fist pushing into your eye that could be the cause. It could very well be an issue of cut off blood flow or too much pressure on the retina from your sleep position. This is not desireable.
Best to be seen by an ophthalmologist; I don't think GP's are very knowledgeable about eye symptoms, and anyway, an eye exam would be in order to be sure there's nothing internally wrong with the eye.