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U.S. college students don’t get enough sleep, and stress is the prime reason, a new study reports.

About 68 percent of college students who were surveyed said that worries about school and life keep them awake, with one-fifth saying this occurs at least once a week. The study, which appears online in the Journal of Adolescent Health, found that less than a third of the 1,125 survey participants get the eight hours of sleep at night that people their age need.

“Students underestimate the importance of sleep in their daily lives,” study co-author Roxanne Prichard, an assistant professor of psychology at the University of St. Thomas, in St. Paul, Minn., said in a news release from the journal’s publisher. “They forgo sleep during periods of stress, not realizing that they are sabotaging their physical and mental health.”

Lack of sleep can cause problems with a person’s immune and cardiovascular system and increase the likelihood of other health risks, such as weight gain, she said.

About three in five of the students said they have irregular sleep-wake patterns, and many said they use drugs or alcohol regularly to help them either sleep or stay alert, the survey found. The regular use of stimulants and sedatives can increase the chance of becoming addicted to them.

Weekday all-nighters are pulled at least once a month by 20 percent of those polled, and 35 percent said they stayed up until 3 a.m. at least once a week. Skipping three or more classes in a month or falling asleep in class was common among 12 percent of the poor sleepers, the researchers noted.

Parents of young children identified fewer than half of the potential safety hazards for kids in a home, but did far better than either health-care professionals or day-care workers, a new study finds.

The University of Alabama at Birmingham study also found that the mothers and fathers recognized fewer hazards when asked to note possible issues for their children as opposed to other toddlers in general, suggesting they thought their children knew better or were less vulnerable than others.

The study had the three groups of adults place stickers on what they considered safety issues in a mock living room, child’s bedroom and bathroom. The researchers placed items such as prescription medication, cleaning products and marbles in the rooms, in addition to the inherent hazards such as the toilet and sink in the bathroom.

The parents, whose children were between 1 and 3 years old, marked only 47 percent of the safety hazards when asked to identify those that posed a risk for other children, and only 40 percent when asked to find ones that might be an issue for their children, according to the findings to be published in Accident Analysis and Prevention. Day-care employees noted only 37 percent of the hazards, while health-care professionals marked only 29 percent of them.

“While there were no benchmarks to assess whether this is a good or bad rate of recognition, it is concerning if it approximates behavior in real homes,” the authors, doctoral student Joanna Gaines and pediatric psychologist David Schwebel of the University of Alabama at Birmingham, said in a news release.

The National Center for Injury Prevention and Control says accidents are the leading cause of death for toddlers in the United States. More than 1,300 children aged 1 and 2 years died from unintentional injuries in 2005.

While formal schooling did not affect how well they recognized the hazards, Gaines noted that adults with more parent-related education, such as taking CPR courses or just reading parenting magazines, did better at spotting the potential safety issues.

Women who breast-feed their babies even for short periods of time may lower their risk of developing premenopausal breast cancer if they have a family history of the disease.

“We saw a 59 percent lower risk of breast cancer among women with a family history who had ever breast-fed,” stated Dr. Alison Stuebe, lead author of a study appearing in the Aug. 10/24 issue of the Archives of Internal Medicine. “It is surprising to see this really strong association with a pretty decreased risk.”

Stuebe is an assistant professor of obstetrics and gynecology at the University of North Carolina at Chapel Hill School of Medicine, but she conducted the study while affiliated with Brigham and Women’s Hospital/Harvard Medical School in Boston.

The risk reduction was seen in women who had breast-fed for as short a period as three months.

Numerous other benefits of breast-feeding have been found, not just for babies but for mothers as well.

A study released in April, for instance, found that women in their 60s who had breast-fed for more than 12 months over their lives were nearly 10 percent less likely to develop cardiovascular disease, and significantly less likely to develop heart disease risk factors, such as high blood pressure, diabetes and high cholesterol.

Previous research on the connection between breast cancer and breast-feeding has been limited, although other, less rigorous, studies have also suggested a decrease in risk.

This study looked at about 60,000 women who had given birth at least once and were participating in the Nurses’ Health Study II.

The lowering in the risk of breast cancer was seen only in women who had breast-fed and who had a mother or sister who had had the malignancy. And it only applied to premenopausal breast cancer.

The lowering of risk was about the same as seen with hormonal treatments such as tamoxifen in women at high risk for a malignancy, the authors stated.

There was no reduced risk in women who did not have a family history of the disease. Nor was there any difference depending on how long the mother breast-fed or the intensity of breast-feeding (whether the baby was breast-fed exclusively or not).

The reduced risk did not seem to have any link with hormones, given that the risk did not differ with the amount of time a woman went without a period while breast-feeding.

The researchers postulated other hypotheses to explain the link.

“It may be something about the first couple of days postpartum if the woman doesn’t breast-feed,” Stuebe said. “The breast tissue has to shut down, and there’s a lot of inflammation and discomfort. Perhaps on a molecular level there’s going some kind of damage.”

This theory is supported by the fact that women who used medication to stop lactating also had a lower risk.

“This data would suggest it’s more of the effect of milk being taken out of the breast tissue after pregnancy that’s beneficial,” Stuebe said. “We know that just being pregnant reduces the risk of breast cancer compared with not having been pregnant. Getting milk out afterwards appears to be part of the phenomenon.”

The real value of the study, added Dr. Richard Bleicher, co-director of the breast surgery fellowship at Fox Chase Cancer Center in Philadelphia, may be less in the clinical implications but in the fact that it helps point researchers towards avenues for understanding the mechanisms of breast cancer.

Eating a Mediterranean diet, which emphasizes fruits, vegetables, legumes and healthy fats, and increasing physical activity levels can reduce the risk of developing Alzheimer’s disease, a new study shows.

The latest research, published in the Aug. 12 issue of the Journal of the American Medical Association, is more evidence that healthy living can help ward off cognitive decline.

Following both healthy habits is a plus, said study author Dr. Nikolaos Scarmeas, an assistant professor of neurology at Columbia University Medical Center in New York City. “There is some evidence [already] that a healthy diet, the Mediterranean diet, may be protective for our risk of getting Alzheimer’s disease,” he said. “In the current study we wanted to see if there was an independent effect of physical activity and diet.”

So Scarmeas and his team looked at 1,880 men and women without dementia living in New York, average age 77, and gave them tests every 1.5 years from 1992 through 2006, evaluating how well they followed a Mediterranean-type diet and their weekly participation in various physical activities. Those in the highest group got a median of 1.3 hours of vigorous activity or 2.4 hours of moderate-intensity exercise every week.

Scarmeas’ team followed the elders for an average of 5.4 years, finding that 282 developed Alzheimer’s disease during that time.

“There was an association between both a healthy diet and physical activity and reducing risk for Alzheimer’s disease,” Scarmeas said.

Those who ate well and exercised had a 60 percent reduction in the risk of developing Alzheimer’s disease compared with those who didn’t follow either good health habit, he said. “It’s a very significant reduction,” he added.

Exactly which components of the Mediterranean diet seem to confer benefit isn’t known. “It could be there are individual elements of the diet that are important,” Scarmeas said. “But it could be the interaction.”

In another study published earlier this year, Scarmeas found that those who adhere to a Mediterranean diet had a lower risk of developing cognitive impairment, and a lower risk of developing Alzheimer’s disease if they already had cognitive impairment.

In a second study in the same journal, researchers (including Scarmeas) looked at 1,410 French adults and found adherence to a Mediterranean diet was linked to slower decline on one cognitive test but not others. They didn’t find high adherence to the heart-healthy diet linked with the risk for dementia.

In an editorial, the Mayo Clinic’s Dr. David Knopman writes that a healthy diet may help prevent Alzheimer’s but does not seem to occur in isolation.

“For such a benign intervention as diet and exercise, 60 percent [reduction in Alzheimer’s] is substantial,” said Dr. Greg Cole, associate director of the Mary S. Easton Center for Alzheimer’s Disease Research at the University of California Los Angeles David Geffen School of Medicine.

Already, about 5.3 million Americans have Alzheimer’s disease, according to the Alzheimer’s Association, and up to 16 million may have it by 2050.

“So, the 60 percent reduction from diet and exercise can have a huge impact because we are talking about so many millions of people,” Cole said.

The findings are in line with what the Alzheimer’s Association already recommends in its “Maintain Your Brain” program, said William H. Thies, vice president for medical and scientific relations for the organization.

“One of the things that is important [to note] is, they are looking at normal people,” he said, not those who already have the disease. “You aren’t going to cure Alzheimer’s disease by eating lots of olives.”