Lack Of Sleep Increases Risk Of Coronary Heart Disease

Those who get less than 8 hours sleep a night are more likely to develop coronary heart disease in later life according to the results of a Canadian study published in the Archives of Internal Medicine in January 2003.

The researchers looked at a group of almost 72,000 middle aged women from the United States who were initially free of heart disease.

The study, which began in 1984, continued for ten years. During the study period 934 cases of coronary heart disease were observed. The researchers found that the women who slept for 5 or less hours a night were 39% more likely to develop coronary heart disease during the study than women who slept for 8 hours a night. Those who slept for 6 and 7 hours a night were 18% and 10% more likely to develop heart disease respectively.

The researchers also found that too much, as well as too little sleep, increased heart disease risk. Nine or more hours of sleep a night was associated with a 37% increase in the risk of coronary heart disease.

The optimal amount for adults is thought to be between 7.5 and 8.5 hours a night however less than a quarter of adult Americans are thought to get this amount of sleep.

Short term sleep deprivation is known to cause many adverse effects on the cardiovascular system such as disturbances in the rhythm of the heart, higher blood pressure, impaired glucose tolerance (a precursor to diabetes), and higher cortisol levels – a stress hormone that has been implicated in heart disease.

Lack of sleep was also more common amongst overweight individuals and it is possible that some of the observed relationship between sleep and heart disease was due to weight rather than a lack of sleep however even after the results were adjusted for confounding factors such as BMI, depression, and snoring the relationship still existed.