Typically, a hangover begins within several hours after the end of a drinking bout. This occurs when a persons blood alcohol concentration (BAC) is falling. Symptoms usually peak about the time the BAC returns to zero and may continue for up to 24 hours after.
Generally, the greater the amount and duration of alcohol consumption, the more prevalent the hangover. There are some people who experience hangover symptoms after drinking low levels of alcohol and some heavy drinkers that do not experience hangovers at all. A recent survey on the prevalence of hangovers found that approximately 75% of those who drank to intoxication reported experiencing a hangover at least some of the time.
For most drinkers, hangover effects will probably not extend beyond common symptoms. The most commonly reported hangover symptoms include:
- Irritability, bad mood
- Extreme Thirst
- Nausea, vomiting, and/or dry-heaves
- Vertigo (dizziness that becomes worse with movement)
- Light and sound sensitivity (loud noises and bright lights cause pain/discomfort)
- Inability to think clearly
- Muscle fatigue and pain
- Sweating, tremors
There are a variety of factors that determine how bad a hangover is. The primary causes of hangover are believed to be dehydration and related electrolyte imbalance, blood sugar regulation disturbance, acute withdrawal, toxicity from alcohol metabolites, interaction with congeners (non-alcohol components of drinks), and reduced sleep quality.
Dehydration and Electrolyte Imbalance – Alcohol is a diuretic. Diuretics cause the body to urinate more than normal, leading to dehydration and electrolyte imbalances. Alcohol intake inhibits ADH (also known as vasopressin) which alters how urine is produced. Reduced ADH levels cause more urine to be produced. Electrolytes (salts such as sodium, potassium, or magnesium) are expelled with the urine. Dehydration and electrolyte imbalances can cause dizziness, thirst, dryness of mucous membranes, lightheadedness, weakness, and difficulty thinking clearly even with minimal fluid output. Sweating, vomiting, and diarrhea also commonly occur during a hangover. These conditions can result in additional fluid loss and electrolyte imbalances.
Gastrointestinal Disturbances Alcohol directly irritates the stomach and intestines, causing inflammation of the stomach lining (gastritis). You may experience delayed stomach emptying. This symptom is especially prevalent when beverages with a high alcohol concentration (greater than 15%) are consumed. High levels of alcohol consumption also can produce fatty liver, an accumulation of fat compounds called triglycerides and their components in liver cells. Alcohol also increases the production of gastric acid and pancreatic and intestinal secretions. Any (or a combination) of these factors can result in the upper abdominal pain, nausea, and vomiting experienced during a hangover.
Blood Sugar / Hypoglycemia – Alcohol ingestion can cause changes in blood sugar levels. Hypoglycemia (low blood sugar) can contribute to weakness, fatigue and bad mood. Alcohol metabolism can lead to fatty liver (described above) and a buildup of an intermediate metabolic product, lactic acid, in body fluids (lactic acidosis). Both of these effects can inhibit glucose production. Because glucose is the primary energy source of the brain, hypoglycemia can contribute to hangover symptoms such as fatigue, weakness, and mood disturbances. Diabetics are particularly sensitive to the effects of alcohol on blood glucose.
Sleep Quality – It is common for people to drink heavily just before or during their normal sleep period. Drinking heavily contributes to poor sleep quality. Reduced sleep quality and duration contributes to hangover-related tiredness and generally worsens other hangover symptoms. When drinking takes place in the evening or at night (as it often does), it can compete with sleep time, thereby reducing the length of time a person sleeps. Alcohol also disrupts the normal sleep pattern, resulting in a decrease of time spent in REM sleep and increasing the time spent in deep sleep. In addition, alcohol relaxes the throat muscles, resulting in increased snoring and, possibly, periodic cessation of breathing (sleep apnea). Alcohol disrupts the normal 24-hour (circadian) rhythm in body temperature. This can result in a body temperature that is abnormally low during intoxication and abnormally high during a hangover. Alcohol intoxication also
interferes with the nighttime secretion of growth hormone, which is important in bone growth and protein synthesis. The disruption of circadian rhythms by alcohol use induces a sort of jet lag that accounts for some of the effects of a hangover.
Headaches The most commonly reported hangover symptom is a headache. Alcohol intoxication results in vasodilatation, which may induce headaches. Alcohol has effects on several neurotransmitters and hormones that are implicated in headaches, including histamine, serotonin, and prostaglandins.
Short-term tolerance and withdrawal – Alcohol causes short-term tolerance followed by acute withdrawal as blood levels fall. This may lead to withdrawal effects as the alcohol is cleared from the system. This withdrawal effect is the reason the “hair of the dog” hangover remedy works at all (drinking more alcohol to combat a bad hangover). The mechanism for the acute withdrawal symptoms is currently believed to be GABA receptors and glutamate receptors as the body counterbalances the sedative effects of the alcohol. As alcohol levels in the bloodstream return to normal, it takes time for the GABA and glutamate systems to return to normal.
Alcohol Metabolites – Ethyl alcohol (drinking alcohol) is metabolized by the enzyme alcohol dehydogenase into acetaldehyde. This is then metabolized into acetate by the enzyme aldehyde dehydrogenase. Although acetaldehyde is quickly metabolized by most people, it is toxic at moderate doses and can cause sweating, nausea, and vomiting.
Congeners – Congeners are believed to play a large role in many hangovers. Congeners include tannins, flavorings, colorings, etc. Red wine, for instance, is known to cause mild histamine reactions in many people, but white wine does not. The congeners are believed to contribute to hangovers from drinking darker alcoholic beverages such as red wine, whiskey, brandy, etc.
Long-term tolerance – Regular drinkers tend to have fewer symptoms from hangovers than occasional drinkers. It is likely that those who are regular alcohol users have developed tolerance and the physical ability to manage the toxic effects. Occasional drinkers are more likely to get bad hangovers.
Personal biological differences – Everyone reacts differently to alcohol. Family history, personal idiosyncrasies, and a variety of other poorly understood factors determine whether someone will get a hangover and will determine how bad it is. Whether you experience a hangover or not may change over time – some people who never experience hangovers can suddenly find themselves getting really painful hangovers.
There are many treatments to prevent a hangover, shorten its duration, and reduce the severity of its symptoms, including numerous folk remedies and recommendations. Few treatments have undergone scientific investigation. Time is the most important component – hangover symptoms will usually abate over 8 to 24 hours.
Attentiveness to the quantity and quality of alcohol consumed can have a significant effect on preventing hangovers. Hangover symptoms are less likely to occur if a person drinks small amounts of alcohol. The type of alcohol consumed also may have a significant effect on reducing hangover symptoms. Alcoholic beverages that contain few congeners (pure ethanol, vodka, and gin) are associated with a lower incidence of hangover than beverages that contain a number of congeners
(brandy, whiskey, and red wine).
A few practices may reduce the intensity of a hangover, but they have not been systematically studied. Consumption of fruits, fruit juices, or other fructose-containing foods is reported to decrease hangover intensity. Bland foods containing complex carbohydrates, such as toast or crackers, can counter low blood sugar levels in people who experience hypoglycemia and can possibly relieve nausea. Adequate sleep may ease the fatigue associated with sleep deprivation. Drinking nonalcoholic beverages during and after alcohol consumption may reduce alcohol-induced dehydration.
Certain medications may provide relief for hangover symptoms. Antacids may alleviate nausea and gastritis. Aspirin and other non-steroidal anti-inflammatory medications(ibuprofen or naproxen) may reduce the headache and muscle aches associated with a hangover but should be used cautiously. Anti-inflammatory medications are gastric irritants and may compound alcohol-induced gastritis. Although acetaminophen is a common alternative to aspirin, its use should be avoided during a hangover because alcohol metabolism enhances acetaminophens toxicity to the liver. Caffeine is commonly used to counteract the fatigue associated with a hangover. Although this practice lacks scientific support; it is a common (and reportedly effective) treatment for hangover symptoms.