There a physiological reason for that. Look at the resource requirements for the brain relative to the rest of the body. https://en.m.wikipedia.org/wiki/Brain#

There a physiological reason for that. Look at the resource requirements for the brain relative to the rest of the body. https://en.m.wikipedia.org/wiki/Brain#Metabolism https://en.m.wikipedia.org/wiki/Brain#Metabolism As mental health deteriorates the consumption of resources required by the brain can fall out of rhythm to the detriment of the rest of the body.