Hangover

Hangover, describes the sum of 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 speaking 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 a hyperosmolar state, which in turn causes shrinking of (loss of water) by the brain cells which causes hangover.

Etymology

The term hangover was originally a 19th-century expression describing unfinished business—something left over from a meeting—or "survival." In 1904, the meaning "morning after-effect of drinking too much" first surfaced.

Symptoms

An alcohol hangover is associated with a variety of symptoms that may include dehydration, fatigue, headache, body aches, vomiting, diarrhea, flatulence, weakness, elevated body temperature and heart rate, hypersalivation, difficulty concentrating, sweating, anxiety, dysphoria, irritability, sensitivity to light and noise, erratic motor functions (including tremor), trouble sleeping, severe hunger, halitosis, and lack of depth perception. Many people will also be repulsed by the thought, taste or smell of alcohol during a hangover. The symptoms vary from person to person, and occasion to occasion, usually beginning several hours after drinking. It is not clear whether hangovers directly affect cognitive abilities.

Causes

Ethanol has a dehydrating effect by causing increased urine production (diuresis), which causes headaches, dry mouth, and lethargy. Dehydration also causes fluids in the brain to be less plentiful. This can be mitigated by drinking water before, during and after consumption of alcohol. Alcohol's effect on the stomach lining can account for nausea.

Another contributing factor is the presence of products from the breakdown of ethanol by 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 between 10 and 30 times more toxic than alcohol itself.

These two reactions also require the conversion of NAD+ to NADH. With an excess of NADH, three enzymes of the Citric Acid Cycle are inhibited (citrate synthase, isocitrate dehydrogenase, and alpha-ketoglutarate dehydrogenase) essentially shutting it down. Pyruvate (the end product of glycolysis) starts to accumulate, and the excess NADH drives lactate dehydrogenase to produce lactate from pyruvate in order to regenerate NAD+ and sustain life. This diverts pyruvate from other pathways such as gluconeogenesis, thereby impairing the ability of the liver to compensate for a drop in blood glucose levels, especially for brain. Because glucose is the primary energy source of the brain, this lack of glucose (hypoglycemia) contributes to symptoms such as fatigue, weakness, mood disturbances, and decreased attention and concentration.

Possible remedies

Hangovers are poorly understood from a medical point of view. Health care professionals prefer to study alcohol abuse from a standpoint of treatment and prevention, and there is a view that the hangover provides a useful, natural and intrinsic disincentive to excessive drinking.

Within the limited amount of serious study on the subject, there is debate about whether a hangover might be prevented or at least mitigated; additionally, there is a vast body of folk medicine and simple quackery. There is currently no empirically proven mechanism for prevention except reducing the amount of ethanol consumed, or for making oneself sober other than waiting for the body to metabolize ingested alcohol, which occurs via oxidation through the liver before alcohol leaves the body. A four-page literature review in British Medical Journal concludes: "No compelling evidence exists to suggest that any conventional or complementary intervention is effective for preventing or treating alcohol hangover. The most effective way to avoid the symptoms of alcohol induced hangover is to avoid drinking.

Ineffective or unproven remedies

Recommendations for foods, drinks and activities to relieve hangover symptoms abound. The ancient Romans, on the authority of Pliny the Elder, favored raw owl's eggs or fried canary. while the "Prairie Oyster" restorative, introduced at the 1878 Paris World Exposition, calls for raw egg yolk mixed with Worcestershire sauce, Tabasco sauce, salt and pepper. By 1938, the Ritz-Carlton Hotel provided a hangover remedy in the form of a mixture of Coca-Cola and milk (Coca-Cola itself having been invented, by some accounts, as a hangover remedy). Alcoholic writer Ernest Hemingway relied on tomato juice and beer. Certain mixtures were developed specifically for the purpose. The "Black Velvet" consists of equal parts champagne and flat Guinness Stout, A 1957 survey by a Wayne State University folklorist found widespread belief in the efficacy of heavy fried foods, tomato juice and sexual activity.

Activities said to be restorative include a shower—alternating very hot and very cold water,exercise, and steambath or sauna (although medical opinion holds this to be very dangerous, as the combination of alcohol and hyperthermia increases the likelihood of dangerous cardiac arrhythmias).