MORE THAN a quarter of people stop breathing at least five times an hour for over 10 seconds - a rate considered abnormal by specialists.

MORE THAN a quarter of people stop breathing at least five times an hour for over 10 seconds - a rate considered abnormal by specialists.

In a study of more than 2,000 men and women, scientists also found that one in five men and one in seven women stopped breathing at least 10 times an hour.

Medical experts believe that such interruptions in sleep, known as obstructive sleep apnoea (OSA), can lead to high blood pressure and increased risk of heart disease and fatal heart attacks. It has also been linked to daytime drowsiness, which can put people at greater risk of car accidents.

"What we call respiratory pause is when a person stops breathing for at least 10 seconds," said Dr Joaquín Durán, who is based at a hospital in Vitoria, Spain, and who presented his findings at the ninth annual meeting of the European Respiratory Society (ERS) in Madrid yesterday.

The medical team carried out a detailed study of the sleep patterns of 1,050 men and 1,098 women over a period of four years.

They first visited the participants at home to inquire whether they slept well or not. They used portable equipment to monitor their sleep by recording data ranging from oxygen saturation of the blood, to heartbeat, snoring and bodily position.

The second phase was carried out in hospital so further monitoring of their eye and muscle movements could be carried out. Respiratory sensors and microphones placed on their necks were also used to make accurate measurements of the time during which the person stopped inhaling.

When such stoppages - due in most cases to the obstruction or collapse of the tissues of the throat - occur more than five times an hour, it may lead to other disorders, said Dr Durán.

Many OSA sufferers, who rest badly at night, experience moments of drowsiness during the day. The study found that 22 per cent of the women and 14 per cent of the men said they felt sleepy frequently at least three days a week - both at their job and off work.

The impact can be more serious, leading to potential heart problems. Many doctors believe that there is a direct link with cardiovascular diseases, although the exact causal relationship is still not known.

Dr Robert Davies, a lung specialist at Radcliffe Hospital, Oxford, reported some as-yet-unpublished results, pointing to a link between OSA and high blood pressure.

The link between sleep apnoea and fatal heart attacks was also shown in a Swedish study presented at the ERS conference.

There is one possible therapy for dealing with the ill-effects of OSA. A method, which involves air being blown continuously through a mask that is attached the whole night to the patient's nose, has been shown to maintain breathing and lower blood pressure.