A report published in the November 10 issue of Archives of Internal Medicine finds that people who sleep less than 7.5 hours per day may have a higher future risk of heart disease. Kazuo Eguchi, M.D., Ph.D. (Jichi Medical University, Tochigi, Japan) and colleagues also find an increased risk of heart disease among people who have little sleep combined with overnight elevated blood pressure.

Sleep is becoming a rarer commodity in today's world even though it is likely to have preventive powers against ailments such as obesity and diabetes. "Reflecting changing lifestyles, people are sleeping less in modern societies," write the authors. They also point out that inadequate sleep - and conditions such as sleep-disordered breathing and night-time high blood pressure (hypertension) - are risk factors for cardiovascular disease.

Eguchi and colleagues studied the sleeping behaviors of 1,255 individuals with hypertension for about 50 months. The sample was about 70.4 years of age, on average. The research team collected details on each patient such as sleep duration, daytime and nighttime blood pressure, and events indicating cardiovascular disease such as stroke, heart attack, and sudden cardiac death.

In the total sample, there were 99 cardiovascular disease events during follow-up. Those who slept for less than 7.5 hours were more likely to develop incident cardiovascular disease. The authors add that, "The incidence of cardiovascular disease was 2.4 per 100 person-years in subjects with less than 7.5 hours of sleep and 1.8 per 100 person-years in subjects with longer sleep duration."

The researchers also noticed high rates of heart disease in patients who both slept for shorter durations and had overnight increases in blood pressure compared to patients with normal sleep duration and no overnight blood pressure increase. However, among participants who did not experience an overnight elevation in blood pressure, the occurrence of cardiovascular disease was similar for those with longer and shorter sleep durations.

"Shorter duration of sleep is a predictor of incident cardiovascular disease in elderly individuals with hypertension," conclude the authors. This predictor is strongest when combined with elevated nighttime blood pressure. "Physicians should inquire about sleep duration in the risk assessment of patients with hypertension."

Short Sleep Duration as an Independent Predictor of Cardiovascular Events in Japanese Patients With Hypertension
Kazuo Eguchi; Thomas G. Pickering; Joseph E. Schwartz; Satoshi Hoshide; Joji Ishikawa; Shizukiyo Ishikawa; Kazuyuki Shimada; Kazuomi Kario
Archives of Internal Medicine (2008); 168[20]: pp. 2225-2231.
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Written by: Peter M Crosta