“What actually causes hangovers? If alcohol is metabolized after a few hours, why do I still feel crummy the next day?”
If the data is any indication, at least 75 percent of youwill recognize this feeling: a throbbing headache, exhaustion, queasiness and even muscle fatigue following a night of overindulging. But what is it about drinking alcohol that causes such discomfort?
The cause is a combination of factors, but primarily one: dehydration.
“Alcohol is a diuretic, so you end up losing water. And the dehydration effect is probably the most severe contributor to hangover,” says Dr. Gary Murray, the program director for the Division of Metabolism and Health Effects of the National Institute on Alcohol Abuse and Alcoholism.
The more you drink and the higher the concentration of alcohol in the drinks you choose, the more dehydrated you’re going to be. According to an overview of the research, that’s because alcohol suppresses the release of the hormone vasopressin, which normally repurposes water released by the kidneys back into the body. With the absence of vasopressin, that water is marked for the bladder and eliminated. Alcohol also causes inflammation of the stomach lining, which can cause diarrhea — another dehydrating condition.