Sleeping for less than six hours a night greatly increases the risk of dying from a heart attack or stroke , a study has found. It is the stuff of nightmares for those whose busy work schedule or busy family life means getting up early and staying up late. Scientists claim that the modern tendency to delay going to bed in order to get through more of the items on the 'to do' list has serious health consequences. But take care. Those who have too much sleep are also more likely to suffer a heart attack. While the extra sleeping is unlikely to be the cause, long-term illnesses such as heart disease often make sufferers feel tired, so sleeping for longer than nine hours a night may be an early warning sign.    Researchers found that those who slept for less than six hours were almost 50 per cent more likely to suffer a heart attack and 15 per cent more at risk of strokes. They believe that not having enough sleep disrupts the balance of two key hormones , ghrelin and leptin , which control the appetite. Poor sleepers tend to eat more and are more likely to be fatter, so are at greater risk of high blood pressure and heart disease, which lead to heart attacks and strokes. Experts recommend adults get at least six or seven hours' shut-eye a night to stay healthy.     But as many as 60 per cent of us do not think we are sleeping enough, with a third suffering from sleeplessness. The researchers, from the University of Warwick, warned that trying to push too much into one day by going to bed late and getting up early could lead to serious illnesses later in life. They looked at the sleeping habits of almost 475,000 participants from 15 previous studies across eight countries, including the UK, the U.S., Japan, Sweden and Germany. Their findings, published in the European Heart Journal, show that those who slept for less than six hours were 48 per cent more likely to develop or die from heart disease and 15 per cent more likely to develop or die from a stroke. Not having enough sleep decreases the levels of leptin in our blood, which means we do not feel as satisfied after eating. At the same time, it raises the levels of ghrelin, responsible for triggering  our appetite, thus making us feel hungrier.     The scientists believe that our 'work hard, play hard' society encourages us to sacrifice sleep and ignore our health. The trend for late nights and early mornings is actually a ticking time bomb for our health so you need to act now to reduce your risk of developing these life-threatening conditions. What's the main idea of the passage?
Lack of sleep raises your risk of stroke or heart disease. It raises the levels of ghrelin, thus making us feel hungrier. Sleeping for longer than nine hours a night may be an early warning sign. The scientists believe that our 'work hard, play hard' society encourages us      to sacrifice sleep and ignore our health.