CHICAGO - CUTTING back on sleep could increase the risk of heart disease, a study published Monday found.

Sleeping less than 7.5 hours a night was associated with a 33 per cent higher rate of cardiovascular incidents such as strokes and heart attacks, according to a study in the Journal of the American Medical Association's Archives of Internal Medicine.

Japanese researchers monitored the sleep of 1,255 people with hypertension for an average of 50 months. They tracked daytime and nighttime blood pressure, sleep duration and cardiovascular disease events such as stroke, heart attack and sudden cardiac death.

They recorded 99 incidents of cardiovascular disease, and found the rate among those who slept less than 7.5 hours was 2.4 per 100 person-years. Those who got more sleep had an incident rate of 1.8 per 100 person-years.

Subjects whose blood pressure rose at night also were more prone to heart disease, the study found.

'Shorter duration of sleep is a predictor of incident cardiovascular disease in elderly individuals with hypertension,' wrote lead author Kazuo Eguchi of Jichi Medical University.

Inadequate sleep has also been associated with increased likelihood of obesity, diabetes and several risk factors for cardiovascular disease, including night-time hypertension and sleep-disordered breathing. -- AFP