A hangover - what is it?
A hangover is the unpleasant consequence of having overindulged or had 'one too many' alcoholic drinks. Symptoms usually appear a few hours after stopping drinking, and may include:
- headache
- nausea and vomiting
- diarrhoea
- disturbed sleep and fatigue
- anxiety and irritability
- decreased concentration
- tremor, and
- sweating.
Doctors believe that there are many things that contribute to these unpleasant symptoms, including dehydration and the way alcohol is processed (metabolised) in your body.
How alcohol enters the body
Alcohol is absorbed directly into the bloodstream through the stomach and the small intestine. Food in the stomach slows down the rate at which alcohol is absorbed but does not prevent intoxication or drunkenness. All alcohol that is drunk will reach the bloodstream, no matter how much food is in the stomach. Alcohol is distributed throughout the water in the body, but not the fatty tissue.
How alcohol leaves the body
Sobering up takes time. The liver breaks down about 91 per cent of alcohol, and a small amount leaves the body in urine, sweat and breath. The liver can only work at a fixed rate, getting rid of about one standard drink an hour. Cold showers, exercise, black coffee, fresh air or vomiting will not help.
If you drink a lot at night, you may still have a high level of alcohol in your bloodstream the next day. (Australian Drug Foundation) |
Metabolism of alcohol
Alcohol ---> Acetaldehyde ----> Acetate
Your liver processes alcohol in two steps. Firstly, an enzyme in your liver cells - alcohol dehydrogenase (ADH) - converts alcohol to a toxic substance called acetaldehyde. Acetaldehyde is then converted to acetate (a non-toxic substance) by another enzyme, aldehyde dehydrogenase (ALDH).
Normally, acetaldehyde is quickly converted to acetate and excreted from your body. But when you have had a lot of alcohol to drink, your liver may not convert the acetaldehyde as quickly as usual, and it may build up enough to contribute to the nausea, vomiting and sweating of a hangover.
Direct effects of alcohol
1. Headache
Alcohol dilates the blood vessels in your brain, which can trigger headache pain - one of the most common symptoms of a hangover. Dehydration also contributes to the throbbing headache that many people associate with hangovers.
2. Sleep
While many people find that they fall asleep more easily after drinking alcohol, they often report sleeping less soundly. This is because your body is rebounding from the depressive effect of alcohol, disturbing your normal sleep rhythm, so you won't get as much deep sleep.
3. Low blood sugar
Alcohol can prevent your body from maintaining its usual tight control on blood sugar levels, causing low blood sugar concentration. Low blood sugar is one of the main causes of fatigue and weakness that people experience as part of a hangover.
4. Dehydration
Alcohol is a diuretic, meaning that it stimulates your body to increase urine production, depleting your body of fluid. This can cause dehydration if you've had a lot to drink. Symptoms of dehydration may include dry mouth and thirst, dizziness and headache.
5. Gastrointestinal effects
Alcohol can cause inflammation of your stomach lining (gastritis), leading to nausea, vomiting and stomach pain. Alcohol also stimulates your stomach to produce excess acid, further contributing to nausea and vomiting. Some people also have diarrhoea because alcohol causes your small bowel to absorb less water and propel its contents along more quickly.
Alcohol withdrawal
Some experts believe that at least some of the symptoms of a hangover, such as sweating, anxiety, tremors and increased heart rate, are due to the effects of withdrawing from alcohol. Your nervous system may need to re-adjust as your blood alcohol level returns to zero.
How to avoid a hangover
It's no secret that the more alcohol you drink, the more likely it is that you'll have a hangover. So limiting yourself to just a few drinks at a time is the best way of avoiding a hangover. Other things that you should avoid because they increase your risk of a hangover include:
- drinking quickly
- drinking carbonated drinks, such as champagne, which tend to raise your blood alcohol level more quickly than other drinks
- drinking on an empty stomach, and
- smoking when you drink.
Another factor contributing to hangovers are compounds found in most alcoholic drinks known as congeners. Drinks with a higher concentration of these substances tend to cause more severe hangovers. So steer clear of bourbon, whiskey, brandy and red wine, which all contain high concentrations of congeners. Gin and vodka tend to contain fewer congeners than other alcoholic drinks.
Also see our topic: Alcohol - effects from drinking
Support groups
If you are concerned about your drinking, you can contact the support organisations (which include helplines) under Further information and support below.
Original content provided by myDr, reviewed 2005.
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