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MONDAY, Nov. 10, 2008 (Health.com) — People in their 60s and 70s who have high blood pressure may want to make sure they get enough sleep. A new study suggests that if they log fewer than 7.5 hours under the covers every night, they’re at greater risk of heart attack, stroke, and sudden cardiac death than their peers who get more shut-eye.

The risk is even higher if they skimp on sleep and tend to have a hike in blood pressure at night, a problem known as the riser pattern. Most healthy people have a drop in blood pressure at bedtime.

Those who got limited sleep and also had the riser pattern were more than four times as likely to have heart attacks and strokes as those without the combination, according to the study published this week in the Archives of Internal Medicine.

It’s not clear if the shorter sleep times were due to insomnia, sleep apnea, or other problems, or exactly how much time the study subjects actually spent snoozing. (Or if they were taking any medication for sleep issues, for that matter.)

The research team, led by Kazuo Eguchi, MD, PhD, of Jichi Medical University in Japan, asked 1,255 men and women with hypertension how much time they spent in bed (not how much they actually slept), and then monitored their blood pressure for a 24-hour period.

Those who spent fewer than 7.5 hours between the sheets were 1.7 times more likely to have some type of cardiovascular event in the next couple of years, while those who slept little and had a riser blood-pressure pattern were at 4.43 times greater risk.

This type of study can’t determine if simply telling people to spend more time in bed would lead to better sleep or a lower risk of any of these problems. But researchers do know that a lack of sleep can throw off the circadian rhythms of several body processes.

Next: How lack of sleep can affect your health