We know that playing football can damage your health - just look at the injuries to the English squad - but is it any safer to watch? Nearly a week into the World Cup, fans of the beautiful game can watch up to six hours of football on television a day.

Never mind that the matches start as early as 6.30am. Many people will still watch in pubs, or at home with the curtains closed, drinking beer, chain smoking and eating junk food. Emotions and levels of the stress hormone, adrenalin, will be running high. If England beats Argentina tomorrow, even football agnostics will be dancing in the streets. If they lose, the word depressed won't come even close. During the last World Cup a study of patients visiting the accident and emergency department at the Royal Infirmary in Edinburgh showed a surge in medical problems after Scotland lost to Brazil. One man was brought in unconscious after taking a temazepam overdose. He was still wearing his Scotland football strip.

So which health problems are you at risk from during the World Cup? It may be a cliche to clutch your chest when the opposition scores but stress really can trigger a heart attack or a stroke. A Dutch study published in the British Medical Journal showed that deaths from heart attacks and strokes increased by 50% on the day Holland was eliminated from the 1996 European football championship. Only men were affected. One of the authors of the paper, Dr Daniel Witte from the University Medical Centre in Utrecht, says that emotional stress is unlikely to be the only trigger for these deaths.

Heavy drinking, smoking and overeating are also to blame. "The risk of heart attacks and strokes was higher in people who already had a higher risk of these conditions. These are people who have diabetes, high blood pressure, high cholesterol and who have had heart attacks and strokes before. The general public should not be alarmed or worried. Women may be less affected than men because football seems to provoke more stress in men than women," says Witte.

"If you are in a high-risk group and a football fan, the best advice is not to get overly excited by winning or losing and not smoke, eat or drink too much. But you should still enjoy the game."

Other studies suggest that stress may throw the heart into dangerous rhythms or raise blood pressure.

The early starts to matches may put some people off drinking. But pubs will be open and the combination of not getting enough sleep with the alcohol makes intoxication more likely. Being drunk increases the chances of accidents, stomach inflammation and being involved in a fight. But if the team you support win, those five pints of lager may not be so bad for you. "There is some evidence that drinking when you are sad and depressed is more harmful than if you drink to celebrate," says David Nais, a clinical psychologist at the University of London. "If your team win, then your immune system is boosted, so alcohol has less of a negative effect. But alcohol with not enough sleep can harm you because you are more likely to be accident prone."

And, obviously, don't drink and drive - it could ruin someone else's chances of following the World Cup. You only have to be slightly over the legal limit to double your risk of having a car accident.

You would think that we would get used to British teams losing, but we don't. Continually being disappointed is bound to make football fans depressed, isn't it? "It is a great let-down when you lose but this can be cancelled out by having a purpose in life," says Nais. "It is good to have an interest, something to get emotional about. When you are excited about something, you often forget everyday symptoms, the aches and pains you may normally have. It's like being on holiday. But a series of disappoint-ments may make you apathetic and cause a downward -spiral in your mood. It can make you more likely to get coughs and colds."

Then there is the question of split loyalties when only one partner is keen on football. "In my experience of years of counselling, any hobby that becomes obsessive, that takes up a lot of time and some of the emotion away from the relationship, can be a bone of contention," says Julia Cole, a counsellor with Relate, the organisation that helps people with relationship problems. "This is true for men as well as women and the hobby can be anything - aerobics, fishing, gym or football."

The problem is worse if the person who isn't interested in the hobby feels their partner is not emotional or affectionate. "They feel resentful," says Cole. "They ask, 'Why is the passion being spent on football when it doesn't come to me? Why can't they show that feeling to me?'

Alcohol only makes things worse. "People say things they regret with alcohol. Even in small amounts, alcohol loosens inhibitions," she says. "Suddenly, after a few cans of beer, you can say things you wouldn't have said or would have said differently. And once it's said, the hurt is there.

"But in most relationships showing passion when England is winning is a sign that there's some oxygen in the relationship. It's a good thing."

Finally, there is the question of food. In Japan they are snacking on sushi. British fast food isn't quite as healthy. Six weeks stuffing yourself with microwave meals or lager and crisps will not make you obese but it is hardly a well-balanced diet. If the World Cup lasted much longer there would be an epidemic of scurvy due to a lack of fresh fruit and vegetable consumption.

Sitting still with the occasional leap from the couch should England score doesn't constitute taking enough exercise. It can even be dangerous. You can rupture the achilles tendon (where the calf muscle is attached to the back of your heel) if you are unlucky. "It's better to be playing sport than watching it," says Dr Philip Kerr, consultant orthopaedic surgeon at Lister Hospital in Stevenage. "It's unhealthy to be sitting, gaining weight, not exercising your mind or your body. Most people who have aches and pains or back-ache already, find they get worse if they are sitting on soft chairs for long periods of time."

Football fever in moderation will not damage your health. But it may be better to watch highlights rather than all the live matches. "Even with the disappointments, the great thing with watching sport is that you live to fight another day," says Nais. "People bounce back quickly."

Cue watching Tim Henman try, yet again, to win Wimbledon at the end of this month.