Ways alcohol directly contributes to a hangover:
- Dehydration and electrolyte imbalance : Since alcohol consumption increases urine production, it causes the body to become dehydrated, leading to many common hangover symptoms, such as thirst, weakness, dry mucous membranes, dizziness, and lightheadedness. Since sweating, vomiting, and diarrhea can also occur as a result of excessive alcohol consumption, the body may lose additional fluids and electrolytes.
- Gastrointestinal disorders : Excess alcohol can cause acute gastritis. It can irritate the stomach and intestines, causing inflammation of the stomach lining and delayed stomach emptying. Alcohol can also produce fatty liver, gastric acid, and pancreatic and intestinal secretions, all of which can cause abdominal pain, nausea, and vomiting.
- Low blood sugar : Alcohol consumption can inhibit glucose production in the body and deplete glucose reserves stored in the liver. Since glucose is the brain's main source of energy, low blood sugar can produce symptoms of fatigue, weakness, and mood disturbances experienced during hangovers.
- Disturbance of sleep and other biological rhythms : Alcohol-induced sleep is usually of shorter duration and poorer quality than normal sleep. This can cause the fatigue experienced during a hangover. Alcohol can also disrupt the rhythm of daily body temperature, nocturnal growth hormone secretion, and cortisol release, all of which can produce jet lag-type symptoms during a hangover.
- Headache : Alcohol poisoning can cause widening of blood vessels (vasodilation), which can lead to a headache. Alcohol consumption also affects histamine, serotonin, and prostaglandins, hormones thought to contribute to headaches.
- Alcohol withdrawal : Excessive alcohol consumption depresses the central nervous system. When alcohol is withdrawn, the central nervous system can go into a state of unbalanced hyperactivity or an "overdrive" state. This can cause the shaking and rapid heartbeat associated with a hangover. Many of the signs and symptoms of a hangover coincide with those of alcohol withdrawal syndrome.
- Effects of alcohol metabolites : Alcohol is metabolized by alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH), which break down alcohol molecules so they can be eliminated from the body. Alcohol is metabolized by ADH into acetaldehyde, which is then broken down into acetate. Some people have genetic variants of ALDH that allow acetaldehyde to build up in the body and cause toxic effects. Although acetaldehyde is no longer in the body when the blood alcohol level reaches zero, its toxic effects can persist during the hangover period, according to researchers.
Other factors that contribute to a hangover:
- Congeners : Most alcoholic beverages contain chemical compounds, known as congeners, that contribute to the taste, smell, and appearance of the beverage. These compounds may contribute to hangover symptoms. Research has shown that drinks that are basically pure alcohol, such as gin or vodka, cause fewer hangover effects. Drinks that contain more congeners, such as whiskey, brandy, and red wine, tend to cause more hangover symptoms.
- Use of other drugs : People who drink excessively often use other drugs and many of them smoke cigarettes. These substances can cause their own set of hangover-type symptoms. Although the use of marijuana, cocaine, and other drugs can contribute to the conditions that lead to a hangover, their exact effects on an alcohol hangover are not known.
- Personal influences : There is some research showing that certain personality traits, such as shyness, intensify the feeling of hangover and create a feeling of "anxiety." Negative life events and feelings of guilt are also associated with experiencing more hangovers. People who are at higher risk of developing alcoholism also experience more acute hangover symptoms.
- Family history : People who have a family history of alcoholism have a tendency to increase hangover symptoms compared to drinkers who do not have a family history of alcoholism. However, people with a family history of alcoholism tend to consume more alcohol than those without a family history.