I know it's trivial, but it's really winding me up. I keep having very dizzy spells on standing up. Once, this morning, my vision pretty much entirely went.
I've had this before, but only right after giving blood, or while pregnant in v. hot weather.
What causes this? How can I fix it? Is it simply a question of not eating and drinking enough? (I am not eating enough, I think I'm drinking enough. I'm not sleeping enough, either.)