Sleep time linked to heart

Sleeping too little or too much may be bad for your heart, with diabetes and hypertension contributing to this relationship. Most research on sleep duration and heart disease has been in Western populations, except for three studies in Japan. Asian populations may have lower average body weights, different lifestyles, and different dietary exposures, compared with those in Western populations that may affect their risk of cardiovascular disease. To investigate the association between sleeping hours and its effect on cardiovascular health in an Asian population, researchers from Singapore and America studied 58,044 Chinese living in Singapore, aged 45 years or older. During the follow-up of around 10 years, 1,416 participants died of heart disease. The researchers asked the people about their daily sleep duration. Thirty-three of the study participants said they got 7 hours of sleep a night. People who slept for 5 or less or 9 or more hours were more likely to have several heart disease risk factors than those who slept for 7 hours, such as smoking and eating fewer fruits and vegetables and more fat and cholesterol. Even after adjusting the data to account for these risk factors, it was found that people who slept 5 hours or less were 57 percent more likely to die of heart disease, while people who slept 9 hours or more had a 79 percent higher risk. The above findings support the results of other studies that have suggested how long people sleep may be a key predictor of their heart disease risk. Some studies have also suggested that sleeping longer may indicate underlying poor health. To address this fact, the researchers eliminated the first 4 years of follow-up from their analysis, as well as excluded people with diabetes or hypertension. In both cases the results were about the same, suggesting that sleep duration, not ill health, was behind the relationship with heart disease. But when they included people with diabetes and hypertension in their analysis, treating these conditions as risk factors, the link between sleep duration and heart disease mortality weakened. This suggests that diabetes and hypertension - both of which have been linked to sleep duration as well as heart disease death risk - may help explain the relationship between sleep duration and death due to heart disease.

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