How long you sleep is linked with heart health

Studies show that sleeping too little or too much is bad for the heart. Researchers have also noticed that diabetes and high blood pressure may be affected by how long people sleep.

One study included 58,044 men and women aged 45 or over who didn't have heart disease when they joined. Those who slept less than five hours or more than nine hours a night were more likely to die of heart and blood vessel disease over the following years than those who regularly slept seven hours.

Most earlier studies of sleep and heart disease were done in Western societies, except three in Japan. Their results apply to Western populations, which differ from Eastern ones in average body weight, lifestyle and diet, and so in rates of heart disease.

In a study in China between 1993 and 1998, people who slept less than 5 hours or more than 9 hours had more of the other heart risk factors, such as smoking, eating more fatty food and fewer fruits and vegetables. Even so, those who slept less than 5 hours had a 57% higher risk of dying of heart disease, and those who slept more than 9 hours a 79% higher risk.

Thinking that long sleepers might have a different lifestyle, the scientists excluded everyone with high blood pressure or diabetes, but the result stayed almost the same, confirming the link between sleep duration and heart disease.