Heavy snorers are twice as likely to suffer a deadly stroke as those who sleep peacefully, research shows.A major study of more than 25,000 people found the risk of a fatal blood clot more than doubled if someone snored through the night.They were also 80 per cent more likely to have heart disease, researchers found.The alarming findings, published in the International Journal of Cardiology, suggest the dangers of heavy snoring are greater than previously thought. Around three million people suffer with the snoring condition sleep apnoea, with one in four men and one in ten women affected.As sleep begins, the muscles in the airways relax. While this does not pose a problem for most people, in sleep apnoea it leads to breathing being shut off for at least ten seconds.Air vibrates against the soft tissue that stands in its way, causing the characteristic ‘rasping’ sound that snorers make.Once the brain realises breathing has stopped, it sends out a signal for the airway muscles to contract again. This opens the airway and the sufferer normally wakes with a jolt.In mild sleep apnoea, this can happen once every ten minutes. But in more severe cases, it means sleep can be disturbed every couple of minutes. Treatment usually involves sleeping with a mask that pumps air into the throat.But tens of thousands of sufferers are thought to go untreated, and the latest study suggests that the dangers to the heart and brain are greater than doctors thought.Scientists from Shandong University in China came up with their findings after pooling data from 12 earlier studies. The results showed strokes were twice as likely in heavy snorers, but mild snorers faced no increased risk.Scientists think that the problem stems from the blood flow to the heart and brain being affected by constant breathing interruptions. But it may also be due to the fact that heart rate and blood pressure are repeatedly jolted out of their naturally lower state during deep sleep.Strokes hit 150,000 people every year, with 30,000 being fatal. Only cancer and heart disease kill more people. The researchers said: ‘Patients with sleep apnoea will be at higher risk of cardiovascular disease, stroke and death.’Thembi Nkala, senior cardiac nurse at the British Heart Foundation, said: ‘If you think you may have the condition, have a chat to your doctor. 'For many people, it is linked to risk factors for your heart, such as obesity.‘So it’s likely your doctor will help you think about lifestyle changes to improve the condition, such as making sure you take regular exercise.’(dailymail.co.uk)ANN.Az