The evidence continues to mount on the health benefits of adequate sleep. A new study published this week in the Journal of the American Medical Association finds that sleeping less than seven and a half hours a day may be associated with a greater risk for heart disease, particularly for those whose blood pressure spikes overnight.
"Sleep habits have a huge impact on human health," says the study's lead author, Dr. Kazuo Eguchi of Jichi Medical University in Tochigi, Japan. Past studies have linked improper sleep habits - sleeping either too little or too much - to disorders such as obesity and diabetes as well as a higher risk of heart attacks and premature death.
Eguchi's study examined the connection between sleep and heart disease among elderly people. Over a 50-month period, researchers monitored 1,225 people with an average age of 70 and a history of hypertension. For the duration of the study, participants recorded their nightly sleep habits in a sleep diary; their blood pressure was monitored all day and night, using an ambulatory blood pressure monitor, a small halter-like device that takes readings every 30 minutes 24 hours a day. Cardiovascular events including stroke, heart attack and sudden cardiac death were tracked among the participants.
The study found that 99 cardiovascular events occurred among all volunteers. The incidence rate was about 33% higher among people who slept less than seven and a half hours a night and had elevated overnight blood pressure - the so-called "riser pattern" - compared with longer sleepers. But those who slept less than seven and a half hours a night yet experienced no overnight hypertension showed no increased cardiac risk; their rate of heart disease was the same as that of the long sleepers. Particularly when it comes to elderly patients, the authors write that "physicians should inquire about sleep duration in the risk assessment of patients with hypertension."
"Sleep is important [for everyone], from children to the elderly," Eguchi says. "But it is more important when someone has some cardiovascular risk factors like hypertension."
Normally, blood pressure drops during sleep, but if people don't get enough shut-eye, it can exacerbate hypertension - or even cause it - and lead to depression and weakened immunity, according to previous research. Longer sleep is, therefore, especially vital for patients who already have high blood pressure. Maintaining a consistent sleep pattern is also important - tampering with the body's circadian rhythm is associated with a variety of hormonal, metabolic and cardiovascular problems. In late October, Swedish researchers reported that the rate of heart attacks jumped following daylight savings time shifts in the spring and fall. "Our data suggest that vulnerable people might benefit from avoiding sudden changes in their biologic rhythms," Dr. Imre Janszky of the Karolinska Institute in Stockholm wrote.
Research generally suggests that seven to eight hours sleep a night is optimal for adults. Eguchi says his study underscores the special need for elderly, hyptertensive patients to get a good night's sleep. "It's a very important issue in their health," Eguchi says, adding that still more studies need to be done to differentiate between "good" and "bad" sleep. The participants in his study recorded the duration of sleep, but not the quality - for instance, whether they experienced disturbances or nocturnia, the medical term for the need to get up and urinate at night, a common condition among the elderly.
Probing further into the nature of sleep, say researchers, may help determine the precise benefits of sleep - largely still a mystery - regardless of age or medical condition.
Vitamin C or E pills do not help prevent cancer in men, concludes the same big study that last week found these supplements ineffective for warding off heart disease.
The public has been whipsawed by good and bad news about vitamins, much of it from test-tube or animal studies and hyped manufacturer claims. Even when researchers compare people's diets and find that a vitamin seems to help, the benefit may not translate when that nutrient is obtained a different way, such as a pill.
"Antioxidants, which include vitamin C and vitamin E, have been shown as a group to have potential benefit," but have not been tested individually for a long enough time to know, said Howard Sesso of Harvard-affiliated Brigham and Women's Hospital in Boston.
The Physicians Health Study, which he helped lead, was designed to do that. It involved 14,641 male doctors, 50 or older, including 1,274 who had cancer when or before the study started in 1997. They were included so scientists could see whether the vitamins could prevent a second cancer.
Participants were put into four groups and given vitamin E, vitamin C, both, or dummy pills. The dose of E was 400 international units every other day; C was 500 milligrams daily.
After an average of eight years, there were 1,929 cases of cancer, including 1,013 cases of prostate cancer, which many had hoped vitamin E would prevent.
However, rates of prostate cancer and of total cancer were similar among all four groups.
The study was funded by the National Institutes of Health and several vitamin makers. Results were being reported Sunday at an American Association for Cancer Research conference in Washington.
"Well-conducted clinical trials such as this are rapidly closing the door on the hope that common vitamin supplements may protect against cancer," said Marji McCullough, nutrition chief at the American Cancer Society. "It's still possible that some benefit exists for subgroups that couldn't be measured, but the overall results are certainly discouraging.
"The American Cancer Society recommends getting these and other nutrients by eating a mostly plant-based diet with a variety of vegetables, fruits and whole grains. A bonus is that this type of diet helps to prevent obesity, which increases the risk of several cancers."
About 12 percent of Americans take supplements of C and E. The new study does not mean these vitamins have no value, just that they didn't prevent cancer in this group of doctors, who may be healthier than the general population, said Dr. Peter Shields, deputy director of Georgetown University's Lombardi Comprehensive Cancer Center.
The best bet, he said, is to do things that are known to prevent the disease — eat right, maintain a healthy weight, and exercise.
Eating a high-fat diet during pregnancy causes permanent changes in the fetal brain that can result in overeating and obesity early in life, according to a study with rats.
The researchers from Rockefeller University in New York City said their finding is an important advance in understanding mechanisms of fetal programming. It also sheds light on the production of new brain cells, helping to explain the dramatic rise of childhood obesity in the United States over the past three decades.
"We've shown that short-term exposure to a high-fat diet in utero produces permanent neurons in the fetal brain that later increase the appetite for fat," study senior author Sarah F. Leibowitz, director of the Laboratory of Behavioral Neurobiology at Rockefeller, said in a university news release. "This work provides the first evidence for a fetal program that links high levels of fat circulating in the mother's blood during pregnancy to the overeating and increased weight gain of offspring after weaning."
For the study, pregnant rats were fed either a high-fat or a balanced diet for two weeks. Pups born to mothers that ate the high-fat diet ate more, weighed more throughout life, and began puberty earlier than pups born to mothers that ate a balanced diet. The pups born to the mothers that at the high-fat diet also had higher levels of triglycerides in the blood at birth and as adults, and also had greater production of brain peptides that stimulate eating and weight gain.
The study was published in the Nov. 12 issue of the Journal of Neuroscience.
The creation of neurons that increase the appetite for fat may also occur in human babies born to mothers who eat a high-fat diet during pregnancy, Leibowitz said.
"We're programming our children to be fat," she believes. "I think it's very clear that there's vulnerability in the developing brain, and we've identified the site of this action where new neurons are being born. We now need to understand how the lipids affect these precursor cells that form these fat-sensitive neurons that live with us throughout life."