help! all the leaves are yellow!

overnight almost all of my plants leaves turned yellow, not burned yellow but just a bright yellow shade. what is this? the plant is almost ready for harvest. should i just harvest the whole thing?

It's most probable that this is a simple, natural N def. The buds are sucking out all the stored nutes out of the leaves in order to further their development. If this is the case, then you shouldn't worry about anything.

In case this is one of those super duper rare deficiencies, or even a burn it's wisest to post a pic.