Sleeping less than seven and a half hours per day may be associated with future risk of heart disease, according to a new article. In addition, a combination of little sleep and overnight elevated blood pressure appears to be associated with an increased risk of the disease.

"Reflecting changing lifestyles, people are sleeping less in modern societies," according to background information in the article. Getting adequate sleep is essential to preventing health conditions such as obesity and diabetes as well as several risk factors for cardiovascular disease including sleep-disordered breathing and night-time hypertension (high blood pressure).

Kazuo Eguchi, M.D., Ph.D., at Jichi Medical University, Tochigi, Japan, and colleagues monitored the sleep of 1,255 individuals with hypertension (average age 70.4) and followed them for an average of 50 months. Researchers noted patients' sleep duration, daytime and nighttime blood pressure and cardiovascular disease events such as stroke, heart attack and sudden cardiac death.

During follow-up, 99 cardiovascular disease events occurred. Sleep duration of less than 7.5 hours was associated with incident cardiovascular disease. "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 authors write.

Patients with shorter sleep duration plus an overnight increase in blood pressure had a higher incidence of heart disease than those with normal sleep duration plus no overnight increase in blood pressure, but the occurrence of cardiovascular disease in those with a longer sleep duration vs. those with a shorter sleep duration was similar in those who did not experience an overnight elevation in blood pressure.

"In conclusion, shorter duration of sleep is a predictor of incident cardiovascular disease in elderly individuals with hypertension," particularly when it occurs with elevated nighttime blood pressure, the authors note. "Physicians should inquire about sleep duration in the risk assessment of patients with hypertension."

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