This document outlines several habits that can damage the brain: not eating breakfast can lead to brain cell degeneration due to low blood sugar; overeating causes hardening of the brain arteries and decreased mental power; smoking causes brain shrinkage that may lead to Alzheimer's disease; high sugar consumption can cause malnutrition and interfere with brain development; air pollution decreases oxygen to the brain; sleep deprivation accelerates death of brain cells; sleeping with your head covered can decrease oxygen and increase carbon dioxide in the brain; working or studying while sick can damage the brain; lacking stimulating thoughts may cause brain shrinkage; and not engaging in intellectual conversations regularly.