The science of hangovers not completely understood, Oklahoma City doctor says

“Whether you're ringing in the New Year, celebrating a birthday or just having a couple of cocktails with your friends, the consequences of drinking too much alcohol can catch up to anyone,” said Dr. Stephen Prescott, president of the Oklahoma Medical Research Foundation.

As with any other medical condition, there's a proper medical name for a hangover: Velsalgia. The name comes from the Norwegian word “kveis” (uneasiness after debauchery) and the Greek work “algia” (pain).

Velsalgia can cause a number of varying symptoms, including nausea, headache, sensitivity to bright lights or loud noises, and diarrhea. But why?

“The hangover is not as well-studied as the effects of alcoholism and addiction,” Prescott said. “But most doctors agree that dehydration is a key component.”

One way alcohol causes dehydration is by blocking the creation of the hormone vasopressin in the pituitary gland. Vasopressin tells the body to absorb water, so when too much alcohol is consumed, instead of taking in the liquid, the kidneys send it straight to the bladder instead.

For every 250 milliliters of alcohol consumed, the body gets rid of about 900 milliliters of water (along with electrolytes, including potassium and magnesium), causing dehydration, Prescott said.

And even without alcohol, dehydration can cause headaches and body weakness. Water makes the body work, so the body gets very greedy when there's less of it to go around. Organs pull water from the brain, causing it to shrink in size, which then pulls on the membranes connecting it to the skull.

“That headache may seem like a nuisance, but the truth is, it's a warning — drink some water or things will get worse,” Prescott said. “Mild dehydration causes headaches. Severe dehydration can cause brain damage, seizures and even death.”

Drinks' differing effects

If alcohol is causing these problems, why do some drinks make it even worse?

The culprit is something called congeners. The more color and flavor an alcohol has, the more congeners are inside.