Hangover

A hangover /ˈhæŋoʊvər/ (medical terminology: veisalgia) is the experience of various unpleasant physiological effects following heavy consumption of alcoholic beverages. The most commonly reported characteristics of a hangover include headache, nausea, sensitivity to light and noise, lethargy, dysphoria, diarrhea and thirst, typically after the intoxicating effect of the alcohol begins to wear off. While a hangover can be experienced at any time, generally a hangover is experienced the morning after a night of heavy drinking. In addition to the physical symptoms, a hangover may also induce psychological symptoms including heightened feelings of depression and anxiety.

Hypoglycemia, dehydration, acetaldehyde intoxication, and glutamine rebound are all theorized causes of hangover symptoms. Hangover symptoms may persist for several days after alcohol was last consumed. Approximately 25-30% of drinkers may be resistant to hangover symptoms. Some aspects of a hangover are viewed as symptoms of acute ethanol withdrawal, similar to the longer-duration effects of withdrawal from alcoholism, as determined by studying the increases in brain reward thresholds in rats (the amount of current required to receive from two electrodes implanted in the lateral hypothalamus) following ethanol injection. Dehydration is caused by alcohol's ability to inhibit the effect of anti-diuretic hormone on kidney tubules, which leads to an interruption of the body's Krebs cycle and the swelling of the brain against the lining of the skull.