Sleep, Less and More, Linked to Heart Disease

Too Much or Too Little Sleep Can Raise Blood Pressure, Stress Hormones

Jan. 24, 2003 -- Catching "Late Night" or "The Tonight Show" may not always be so good for your heart -- and it's not because of the jokes. Getting too little sleep, on a regular basis, puts you at higher risk of heart disease, a new study suggests.

It's part of a growing body of research, all pointing to the negative effects of chronic sleep deprivation. One study showed that partial sleep deprivation for one night - between three and four hours of sleep -- caused an increase in blood pressure. Another study found that four hours of sleep a night, for just six nights, caused increased cortisol (a stress hormone), higher blood pressure, and other negative health effects.

This new study is the first to look at the big picture, at the long-term health consequences of too little shut-eye.

For women between ages 45 and 65, too little sleep seriously increased their risk of heart attack, says researcher Najib T. Ayas, MD, a sleep specialist with Brigham and Women's Hospital in Boston.

"There could be some long-term health consequences," Ayas tells WebMD. His study appears in today's Archives of Internal Medicine.

Too little sleep puts stress on the body, Ayas explains. "It's something people don't take seriously," he says. "People brag about getting only four hours of sleep a night. But no one brags that they don't exercise, that they smoke every day. Sleep is not in the realm of a healthy lifestyle. I'm hoping that's where it will eventually be -- one of the pillars of good health."

Ayas gathered his information from questionnaires completed in 1986 and 1996 by nearly 72,000 women between 30 and 55 years old. In the survey, the women estimated the number of hours of sleep they got in a 24-hour period. Ayas and colleagues also tracked the incidence of heart attacks and heart disease-related events during that 10-year period.

Among this group of women, 271 fatal and 663 non-fatal heart events were documented during the 10-year study period.

Taking into account other factors, like snoring, smoking, and body mass index (BMI), Ayas found: women getting five or less hours of sleep had almost a 50% increased risk of heart disease, those getting six hours of sleep had an almost 20% higher risk, and those with seven hours of sleep had almost a 10% increased risk for heart disease events, when compared to women who averaged eight hours of sleep a night.

Too little sleep was not the only problem. The risk for women reporting nine or more hours of sleep was 38% higher.

Why would too much sleep have an adverse affect on health? Another study had a similar finding, says Ayas. "It may be some unknown factor that's causing them to sleep more, like obstructive sleep apnea or fragmented sleep. Again, it's putting stress on the body."

Another theory: "It's also possible that too much sleep could be bad for you," he adds. "Maybe too much sleep is like too much food, it causes a health risk. I don't think that's true, but other scientists have said that. "

Men have to pay attention to their sleep patterns, too. While this study involved women, "there's no physiological reason why this should not apply to men, too," Ayas tells WebMD.

"There's no question that quality of life ultimately has some relationship with the amount of sleep people get," says Robert Roberts, MD, director of cardiology at Baylor College of Medicine in Houston.

During sleep, blood pressure and heart rate have a chance to rest, and adrenaline quiets down. "That's good not only for the cardiovascular system but also for tissue repair," Roberts tells WebMD.

"However, let's remember that the major risk factors for heart disease include high cholesterol and smoking," he says. "And certainly the biggest one today is obesity, which induces diabetes and increased blood pressure. The fact that sleep reduces blood pressure is reason enough to get more sleep."

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SOURCES: Archives of Internal Medicine, Jan. 27, 2003 • Najib T. Ayas, MD, Brigham and Women's Hospital, Boston, Mass. • Robert Roberts, MD, director of cardiology, Baylor College of Medicine, Houston, Texas.
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