It could be the brain having a hard time getting energy. I heard a neurologist recently talk about that and Alzheimer's and how the brains in those individuals are less efficient at processing energy. Anyway, lack of food, lack of energy, headache, all that might point to lack of brain energy. That's my theory.
Side effects on Paleo plan? 4 Answers
Paleo causing heartburn and headaches? 3 Answers