The science of your hangover

Hangoverville is a place nobody wants to visit, but the road towards it is one many of us end up taking, especially during the party season. The telltale signs of having reached your destination are unmistakable and aptly described on a global scale. "Smacked from behind" is the literal translation of the Swedish word for hangover. Meanwhile, the Salvadoreans describe themselves as waking up "made of rubber", the French with a "wooden mouth" or a "hair ache" and the Danes with "carpenters in the forehead".

"In the past, dehydration was thought to be the main cause of hangover symptoms," says Emma Derbyshire, independent nutritionist and consultant to the Natural Hydration Council. "But now, scientists believe that alcohol withdrawal, and chemicals formed in the body when our livers break down alcohol, also contribute to those dreaded symptoms."

Double dose of toxins

"Having any toxin hanging around in your system will get you in trouble, and alcohol is no exception," says Sneh Khemka, medical director at Bupa International. "It passes through the stomach and into the bloodstream, which distributes it throughout the body, irritating and even damaging cells and cell membranes. As if that's not bad enough, a product of alcohol metabolism that is more toxic than alcohol itself, acetaldehyde, is created when the alcohol in the liver is broken down. So in essence, you get a double whammy of toxins in the body."

The good news is that acetaldehyde is automatically attacked by another enzyme and a substance called glutathione. The process works well, leaving the acetaldehyde only a short time to do its damage, but – and it's an important but – only if you stick to a few drinks. "The liver's stores of glutathione quickly run out when larger amounts of alcohol enter the system," Khemka says. "The acetaldehyde builds up in the body, causing headaches and vomiting."

Muddled internal messages

Ever wondered why your sleep is disrupted after a night on the lash? Alcohol inhibits the production of glutamine, a natural stimulant whose job it is to keep you awake. When you stop drinking later on, your body rebounds by overproducing that stimulant. Not only does this prevent you from getting the deep sleep you need, it also causes fatigue, stomach irritation and a general sense of illness.

"Alcohol also promotes secretion of hydrochloric acid in the stomach, eventually causing the nerves to send a message to the brain that the stomach's contents are hurting the body and must be expelled through vomiting," adds Colin Wilson, research scientist at Water Wellpoint.

Dehydration

One 250ml glass of wine (or other alcohol) causes the body to expel 800 to 1,000ml of water. That's four times as much liquid lost as gained, which explains the heavy traffic to the loos in bars and restaurants.

No wonder that the morning after heavy drinking, the body sends a message to replenish its water supply, usually manifested in a mouth that's so dry it feels as though it's been stuffed with cotton wool. "Headaches also result from dehydration as the body's organs try to make up for their own water loss by stealing water from the brain," Wilson says. "This makes the brain decrease in size and pull on the membranes that connect the brain to the skull." Hence those carpenters.

There's a third effect of dehydration. "Frequent peeing expels salts and potassium that are necessary for proper nerve and muscle function," Wilson explains. "When levels of these get too low, headaches, fatigue and nausea can result."

Withdrawal

"Tremors and sweating – both common features of hangovers – are due to alcohol withdrawal," says Jonathan Chick, honorary professor in health sciences at Queen Margaret University, Edinburgh and medical adviser to Drinkaware. "The brain adapts even in the course of one evening of drinking and is then left in a withdrawal state for the next 24 hours. That's why some people swear by a hair of the dog – another alcoholic drink – to cure their hangover."

This method merely postpones the inevitable, he says, although there is a school of thought that it may mitigate the worst symptoms.

Other causes

Over-consumption of alcohol can induce hypoglycaemia (low blood sugar), which converts into light-headedness and general weakness, Chick says.

A few too many glasses of whatever your tipple is can also produce inflammation, which in turn causes the white blood cells to flood the bloodstream with molecules called cytokines – the same molecules released when you get the flu. The result is headaches and nausea, as well as lethargy which encourages us to stay in bed, thereby freeing up the body's energy for use by the white blood cells in combating the invader.

Even the noise levels of the environment in which you drank can influence a hangover, Chick says. "People's hearing when they drink becomes slightly dulled, which is why they tend to raise their voices and the music gets turned up. Overall exposure to high decibels becomes common and definitely contributes to morning-after headaches."

The depressive nature of alcohol is also significant, certainly in contributing to the emotional self-doubting, over-anxious component of hangovers. You might feel happy while you drink, but alcohol works much like diazepam – ultimately a downer, not helped by the plummeting blood-sugar levels that zap your energy when you've finished drinking.

Finally, there's the fact that alcohol breaks down the body's store of glycogen in the liver. Lack of this key energy source is at least partly responsible for the weakness, fatigue and lack of co-ordination the next morning.

Mine's worse than yours

In general, darker drinks – think red wine and whisky – contain a much higher level of toxins called congeners (by-products of fermentation) than white wine and clear spirits such as vodka, gin and rum. "More expensive brands tend to have fewer congeners," Derbyshire adds.

Habitually heavy drinkers tend to get milder hangovers. Meanwhile, women who drink the same amount as men tend to suffer more. It's partly to do with body size, but also because women have lower levels of enzymes and glutathione, which means it takes longer for their bodies to break down the alcohol. "The older you get, the more severe your hangovers become," Khemka adds. "The body is more susceptible to toxins and less able to produce the enzymes needed to deal with them."

Genes matter, too, he says. "Up to 70 per cent of people of oriental origin have a variant, less efficient form of ethanol dehydrogenase, an enzyme necessary for alcohol processing. "Many feel flushed and drunk very quickly."

Prevention

"Most people think of a fry-up as a cure, but slower absorption of alcohol – and therefore the effects of too much of it – can be achieved by eating a meal before you start drinking," Wilson says. Fat is particularly efficient at preventing absorption, which is why some people in the Mediterranean drink a teaspoon of olive oil before drinking. At the very least, have a glass of milk. Multivitamins can help, too, preparing the body for the depletion of vitamins that you'll experience later when frequently urinating.

"Stay well-hydrated during the day to prepare for your night out," Derbyshire advises. "Having a bottle of water at hand is a great way to hydrate on the move."

Have a glass of water with every drink you order, she adds. But limit fizzy drinks as the gas bubbles stimulate the gastric sphincter to open and facilitate gastric emptying. It's why fizzy alcohol such as champagne really does "go straight to the head". Avoid salty snacks, too, as these make you more likely to drink more alcohol.

Just before bed after a heavy night out, Koreans have a tradition of downing a bowl of water with honey. The idea is to head off the hypoglycaemia, as well as hydrate. It's not a bad theory, but if you suspect your beer goggles may hinder the search for the honey pot, it's still worth consuming buckets of water.

Cure

First, the bad news: there is no miracle hangover cure. The stumbling block for inventing one is research. Lab tests with cell samples or animals are easy enough, but clinical trials with humans raise both practical and ethical dilemmas. But there's no hard evidence they really work, certainly for all symptoms, Emma Derbyshire insists.

That said, certain painkillers have been found to be more effective than others when it comes to hangovers. Aspirin, for instance, is both a non-caffeinated pain reliever and a type of anti-inflammatory known as a prostaglandin inhibitor. High levels of prostaglandin have been linked to hangover severity. However, it is not gentle on the stomach, so avoid it if you've been vomiting or you haven't eaten.

Herbal compounds have become increasingly popular for hangovers. These include ingredients such as milk thistle, guava leaf and ginseng, which aim to boost biochemicals that help the body to deal with toxins. But again, the evidence is scant, with the exception of milk thistle, which has been proven to protect cells from alcohol damage.

Water goes a long way to speeding up the healing process. If you can stomach it, add salt and sugar to it to replace the sodium and glycogen lost the night before. Fruit juice is also good – the sugar helps to increase the body's energy, while the vitamins and nutrients can help to replace those depleted the night before due to alcohol's diuretic effect.

Bananas and kiwi fruit can both restore potassium to your body which has been lost to alcohol's diuretic effect. Power drinks help in the same way. Meanwhile, eggs contain large amounts of cysteine, which can mop up left-over toxins.

Avoid coffee – it will further dehydrate you – and remember that eating fried or fatty foods will probably just irritate your stomach further.