Ninety-three decibels is the noise level of a powerful lawn mower; a jet engine is only slightly noisier. It is also the recorded level of the world’s loudest snorer.

While few of us can imagine trying to sleep alongside such a racket, many will have had to cope with the snorts, wheezes and rumbles of a snorer at some time or another. Almost one adult in two snores occasionally, and half of these are habitual snorers. For those who snore - and those who have to live with them - it is no laughing matter. Snoring can threaten health, affect work performance and destroy relationships.

These devastating effects are due to simple physiological changes that occur during sleep. When we sleep, our muscles relax. The airways partially collapse, reducing breathing space.This blockage causes vibrations of the soft palate and other tissue in the mouth, nose and throat. Many snorers also have swollen tissue or congestion, which magnifies the problem.

Eileen is a teacher from Bedfordshire. Her husband has snored for the past 20 years. “He’s so bad that the bed vibrates, so earplugs don’t do the trick,” she says. “I moved into the spare room first, then into the garage. Our neighbours suffer too, because our semi has thin walls. We can’t go on holiday or have friends to stay. His snoring rules our lives.”

Eileen and her husband have tried to work out why he snores, but it is not easy. Snoring has many causes, often working together. It can take the most painstaking detective work to find the root of the problem.

Obesity, lack of exercise and alcohol are all prime causes. Men in particular are prone to putting on weight around the neck, and this fatty tissue squeezes and constricts the airway. If this is not enough on its own, a couple of pints of beer can tip the balance. Alcohol further relaxes the muscles and causes the throat structure to sag. Cue sound effects.

Anything that irritates the nose or throat - such as smoke, dust and faeces of the house-dust mite - can also cause snoring. If the nasal passages become congested by swelling or catarrh, breathing through the nose can become difficult. And, with mouth-breathing, snoring becomes increasingly likely. As with debilitating breathing conditions such as asthma, snoring is often triggered by an allergy - maybe to pillow feathers or pet hairs.

Ten years ago, Marianne Davey was in the same position as Eileen. Her husband had been snoring for years, and doctors were no help. She struggled to persuade anyone to take the condition seriously, and could find no information on how to track down the cause of her husband’s snoring or how to tackle it. In a last-ditch search for a solution, she went to the United States.

“They were light years ahead,” she says. “I found information, support and a range of treatments.” On her return, she set up the British Snoring and Sleep Apnoea Association. The BSSAA now receives up to 200 calls a day and publishes a regular newsletter encouraging sufferers to work their way through treatments until they find the right one. “We want people to realise they’re not alone,” says Marianne Davey. “We try to offer support and to raise awareness of the problem nationally. GPs are often accused of not taking snoring seriously, but I think it’s more that they just don’t know what to do.”

The seriousness of the effects of snoring can be difficult to grasp for those whose only night-time disturbance is the bin lorry or the dawn chorus. Even snorers who are not woken by the noise will have a severely impaired quality of sleep. Fatigue, loss of concentration, headaches and depression are all common. Tired snorers are more likely to have an accident at work or fall asleep at the wheel. Snorers also seem to be at increased risk of high blood pressure and strokes.

Chronic snoring is also associated with a more serious condition, sleep apnoea, in which the airways become totally obstructed. Sufferers stop breathing for up to 10 seconds a time up to 300 times a night, causing them to wake every two or three minutes. This can reduce blood oxygen levels and cause long-term changes to the cardiovascular system.

And it is not just the snorer who suffers. Anyone who has to live with a snoring partner knows how far the effects extend to the rest of the family. “I wake up tired and cranky,” says Eileen. “I can sleep during the day at the drop of a hat - and often do. It’s impossible to explain to other staff in school. They just say, ‘Oh, it can’t be that bad’ and imply I’m making a fuss.”

Denise Knowles is a counsellor for Relate, and sees many couples whose lives are blighted by noisy nights. Many come to her for help because they quarrel constantly. “It’s never mentioned at first. It’s always about the arguments. But then you find out that they argue because they’re always tired, and they’re tired because one of them snores. They might not have had a good night’s sleep in years and it’s taking its toll on the relationship.”

Escaping with the duvet into the spare room is also destructive. Night-time cuddles and pillow-talk are replaced by a tense wait for the noise to begin. Over the years, physical and emotional intimacy drains away.

And those just starting out on relationships, can find snoring a real hurdle to romance. “I’m 23 and I’ve had several offers but only one boyfriend,” says Jane, a newly qualified teacher from South Yorkshire, and proof that it’s not only men who are serious snorers. “I’m frightened that once a boyfriend hears me snore, he’ll dump me. I have no self-confidence; my snoring has destroyed it.”

For anyone in Jane’s position, getting treatment for snoring is a matter of urgency. But because the condition and its causes vary, finding the right cure can take time. Sometimes a change in lifestyle can be enough. Losing weight; avoiding alcohol, snacks or tobacco within four hours of bedtime; avoiding sleeping pills; and sleeping on your side rather than your back can all help. Some sufferers also swear by eating a raw garlic clove before bedtime, although this may have its own impact on your love-life.

Those in need of something a little more powerful can choose from a range of devices designed to make breathing easier. Decongestant sprays and nasal strips such as those favoured by athletes can help, while the more desperate opt for full masks with breathing hoses and pumps. Tellingly, a large slice of the market is for those sleeping alongside the snorer; they can choose from a wide range of earplugs.

As a last resort, surgery is available. There are four basic procedures, including the Scrabble-busting uvulopalatopharyngoplasty. All aim to reduce or tighten the vibratory tissue in the mouth and throat. But be warned - waiting lists are long, the procedures painful and success far from guaranteed. Many patients return to snoring within years or even months, especially if they put on weight.

As a history teacher, Eileen can cite plenty of examples of famous, and successful, snorers - George Washington, Winston Churchill, Johannes Brahms. “But they never tell you about the wives,” she says. “After all, the wife of the world’s loudest snorer went deaf in one ear.” Which explains the sentiments behind her favourite epigram, coined by author, critic - and snorer - Anthony Burgess. “Laugh and the world laughs with you. Snore and you sleep alone.”

The British Snoring and Sleep Apnoea Association runs a Freephone helpline, 0800 085 1097. It has a website at www.britishsnoring.co.uk with an online shop offering snoring treatments

WHY DO YOU SNORE?

Cause Tongue-based obstruction.

Test Try making a snoring noise with your mouth closed. Then stick your tongue out, grip it between your teeth and try again. If you make a snoring noise with your tongue in but not when it’s out, you are probably a “tongue-based snorer”.

Solution Using a snorer’s gum-shield will keep your lower jaw forward and prevent the tongue collapsing.

Cause Nasal blockage or inflammation.

Test Close off one nostril and breathe through the other, then reverse. Repeat the test last thing at night, and first thing in the morning. Any obstruction to breathing could be a problem.

Solution Consider possible allergies, such as to pet hairs. Give the room in which you sleep a thorough spring-clean. Try using a nasal spray or inhaling steam from a bowl of hot water.

Cause Collapse of the soft palate.

Test Try to tape-record your snoring. Nasal snoring usually has a sharp, clearly defined sound. Palatal snoring will sound softer and more diffused.

Solution Range of mouth guards designed to keep the mouth closed during sleep. Try losing weight, especially if your collar size is over 16 12. Avoid alcohol for four hours before bed.