Blood and vitamin B are two things your brain needs to function (blood for nutrients, and vitamin B for both nutrients and neurotransmitter production - acetylc

Blood and vitamin B are two things your brain needs to function (blood for nutrients, and vitamin B for both nutrients and neurotransmitter production - acetylcholine, dopamine, gaba, serotonin, histamine), so I suppose such an effect is possible, although a lot of it could also be credited to the fear of dying.