Heaven's Gift

Please explain why a person can have a drastic swing in thinking. Mr Z can 'think normally' at one moment and then can have a totally different thinking in the next moment.

An individual's mental state is a function of his nutrient and energy level. If the person has low nutrient level, he tends to think negatively as correct thinking requires a full spectrum of nutrients. The same with energy. If the person has low energy level, his thoughts tend to be scattered, confusing and mostly negative. Hence to improve a person's thinking, nutritional and energetic deficiency needs to be addressed. While I believe learning the truth also plays a significant role in stabilising one's thinking, I am not sure how it works. Anyone can shed some light?