How does alcohol cause hangovers?
Hangovers are multi-causal. Ethanol has a dehydrating effect by causing increased urine production (such substances are known as diuretics), which causes headaches, dry mouth, and lethargy. Dehydration causes the brain to shrink away from the skull slightly.[4] This can be mitigated by drinking water or an oral electrolyte solution after consumption of alcohol. Alcohol’s effect on the stomach lining can account for nausea. Because of the increased NADH production during metabolism of ethanol by the enzymes alcohol dehydrogenase and aldehyde dehydrogenase, excess NADH can build up and slow down gluconeogenesis in the liver, thus causing hypoglycemia. Another factor contributing to a hangover are the products from the breakdown of ethanol via liver enzymes. Ethanol is converted to acetaldehyde by the enzyme alcohol dehydrogenase, and then from acetaldehyde to acetic acid by the enzyme acetaldehyde dehydrogenase. Acetaldehyde (ethanal) is mildly toxic, contributing to hangover. These two
