Daytime naps may enhance memory skills: study

Date updated: February 05, 2008 
Content provided by Reuters

NEW YORK (Reuters Health) – Taking a 45-minute nap during the day appears to help the brain process some information to memory, research suggests.

“A nap has a beneficial effect on performance across multiple tasks, particularly for subjects who learned the material more strongly before sleep,” Dr. Matthew Tucker told Reuters Health.

“In contrast, a nap does not have the same enhancing effect in subjects who learned poorly prior to sleep,” said Tucker, of Beth Israel Deaconess Medical Center, in Boston, Massachusetts.

Tucker and colleagues tested how a 45-minute daytime nap, compared with no nap, influenced how well 11 male and 22 female undergraduate students were able to memorize factual and spatial information.

The students, all caffeine, alcohol, and medication-free, were aged 23 years on average when they attended a sleep laboratory at The City College of the City University of New York, in New York, to participate in the study.

According to a report in the journal Sleep, the students performed three tasks that required memorization. One involved linking 60 unrelated word pairs, such as tree-nose; another required maneuvering through a computerized maze; and the last gave students 5 minutes to copy a complex figure.

The researchers then randomly assigned students to individual sleep chambers where 16 napped and 17 rested quietly. After about 10 minutes, the no-nap group went to a separate room to watch television while the nappers completed their 45-minute sleep.

Two-hours later, after all the students watched the same movie, the researchers had students recall the word pairs, and measured their speed and accuracy in the computerized maze, as well as their ability to redraw the complex figure from memory.

Among the students deemed high-performers in the initial tests, those who napped performed better than non-nappers on all three tasks at the re-test. By contrast, naps did not enhance the memory among initially low-performing students, the researchers note.

The findings of this study, Tucker said, “clearly suggest that sleep, even in the form of a short daytime nap,” helps the brain selectively process well-learned information.

A logical next step would be to look at the factors that produce enhanced learning and how these factors are associated with memory enhancement during sleep, Tucker added.

SOURCE: Sleep, February 2008

 

©2008 Reuters Limited. All rights reserved. Republication or redistribution of Reuters content, including by framing or similar means, is expressly prohibited without the prior written consent of Reuters. Reuters shall not be liable for any errors or delays in the content, or for any actions taken in reliance thereon. Reuters and the Reuters sphere logo are registered trademarks and trademarks of the Reuters group of companies around the world.

More sun is healthy, despite skin cancer risks

Date updated: January 08, 2008 Content provided by Reuters

LONDON (Reuters) – A little more sunshine might help you live longer, according to new study findings suggesting that for some people health benefits from the sun outweigh the risk of skin cancer.

Sunlight spurs the body to produce vitamin D but fear of skin cancer is keeping many people in the shade and depriving them of an important protection from a range of diseases, researchers said.

“The skin cancer risk is there but the health benefits from some sun exposure (are) far larger than the risk,” said Johan Moan, a researcher at the Institute for Cancer Research in Oslo, who led the study. “What we find is modest sun exposure gives enormous vitamin D benefits.”

A number of studies have found protective effects from higher vitamin D intake for some cancers and ailments such as rickets, osteoporosis and diabetes, Moan said. Certain foods contain vitamin D but the body’s main source comes from the sun.

The researchers calculated that given the same amount of time spent outside, people living just below the equator in Australia produced 3.4 times more vitamin D than people in Britain and 4.8 times more than Scandinavians.

This means even though rates of internal cancers such as colon cancer, lung cancer, breast cancer and prostate cancer rise from north to south, people in the sunnier latitudes were less likely to die from the diseases, the researchers said.

“The current data provide a further indication of the beneficial role of sun-induced vitamin D for cancer prognosis,” said Richard Setlow of the U.S. Department of Energy’s Brookhaven National Laboratory, who worked on the study.

Getting more vitamin D — which helps the body’s immune system work properly — is also critical for people living in places like Scandinavia where long winters and short days during the year limit sun exposure, Moan added.

In Norway, Moan estimated that doubling the sun exposure for the general population would also double the number of annual skin cancer deaths to about 300 but that 3,000 fewer people would die from other cancers.

“The benefits could be significant for people in other countries as well,” he said in a telephone interview. “I would be surprised if they were different.”

Moan, whose findings were published in the Proceedings of the National Academy of Sciences, recommended daily sun exposure for about half the time it takes a person to get sunburn.

Another way to get more vitamin D could be designing sunscreen that blocks long ultraviolet wavelengths that trigger the deadliest forms of skin cancer while letting through short ultraviolet wavelengths that produce the vitamin, the researchers said.

 

©2008 Reuters Limited. All rights reserved. Republication or redistribution of Reuters content, including by framing or similar means, is expressly prohibited without the prior written consent of Reuters. Reuters shall not be liable for any errors or delays in the content, or for any actions taken in reliance thereon. Reuters and the Reuters sphere logo are registered trademarks and trademarks of the Reuters group of companies around the world.

The Best Multivitamin for You

… and 11 to steer clear of.

You’ve been told for years that popping a multivitamin every day might help you live longer. But the daily-multi habit has been getting a bit of bad press lately.

First, ConsumerLab.com, a watchdog of the supplement industry, found that more than half of the 21 multis it tested had too much (or too little) of certain vitamins—or had been contaminated with dangerous substances like lead. Then a controversial paper from researchers in Denmark and other European countries, published in the Journal of the American Medical Association, made the claim that taking vitamins may actually shorten your life.

What’s the real story? Health talked to leading nutrition experts at Harvard and Tufts universities to find out and to get some answers on this and other confusing info about vitamins.

Are multivitamins safe?Vitamins have been recommended for years because they help you get key nutrients if your diet’s low on fruits and veggies—and may even help prevent cancer and heart disease. And it’s unlikely that one critical paper (speculating that vitamin supplements might upset your body’s natural healing process and boost your risk of death) will change that.

Longtime vitamin experts at Tufts University and the Linus Pauling Institute at Oregon State University continue to say multis aren’t dangerous and the paper’s findings are wrong. The paper analyzed previous studies, including many with people who were sick before taking vitamins, so there’s a good chance vitamins weren’t responsible for shortening their lives. Experts say the paper also ignored two major studies that found vitamins reduced the risk of death.

At the same time, the study from ConsumerLab.com shows that you can’t assume just any vitamin is safe. Because there are no uniform manufacturing rules for supplements, a multi may not contain what the bottle claims, could be contaminated with something from the manufacturing plant, or might have tainted ingredients.

Your best bet: Avoid the vitamins singled out by ConsumerLab.com (see “11 Multis to Avoid”), and stick with mainstream names like Centrum Silver and One-A-Day Women’s, which were found to be free of impurities and accurately labeled. Also, check vitamin bottles for the United States Pharmacopoeia (USP), NSF International (NSF), or ConsumerLab.com (CL) seals. The USP and NSF are nonprofit groups that verify whether companies offer contamination-free products and use good manufacturing practices. Not every brand has the seals—some don’t want to submit to testing—but those that do (Kirkland and Nature Made carry the USP seal, for instance) are reliable.

How much should I spend to get the biggest benefits? Price isn’t a sign of quality. In fact, some of the priciest vitamins—like The Greatest Vitamin in the World and Eniva Vibe, which cost more than $39.95 per bottle—failed the Consumer Lab.com tests. A mainstream brand like One-A-Day Women’s is $8.99 for a bottle of 100 tablets atdrugstore.com, about 9 cents per day.

How do I find the right multi for me? In your childbearing years, make sure your multi has 400 micrograms (mcg) of folic acid, which helps make and maintain new cells. And pregnant women should take a vitamin with 600 mcg of folic acid daily; this nutrient also reduces the incidence of neural tube birth defects like spina bifida.

A premenopausal woman should look for a multivitamin with iron to replace the iron lost during menstruation. Menopausal women should go without the iron. “Too much iron may raise the risk of heart disease,” says Meir Stampfer, PhD, professor of nutrition and epidemiology at Harvard School of Public Health.

If you’re taking a prescription, check with your doctor about risky interactions. (Vitamin E, for instance, may be a problem if you’re taking a blood thinner.) If you’re a cancer patient, you should ask your doctor about risks before taking vitamins. “Cancer cells need vitamins to grow, too,” Stampfer says. Plus, some vitamins can interfere with chemotherapy.

What’s the best way to avoid that queasy feeling after taking a multi?“Consider switching brands,” Stampfer suggests. Trial and error is the best way to determine which brands won’t break down poorly in your stomach and lead to irritation. Also, take your multi with food because your body needs some fat (or lipids) to absorb some of the individual vitamins. The delivery method (pill, liquid, gummy bear) makes no difference. But vitamins in liquid form may degrade more quickly on the shelf.

How much of each vitamin should my multi have?The amount per serving numbers on the label should match the government’s Dietary Reference Intakes (DRI). It’s OK if they’re higher as long as they don’t exceed the tolerable upper limit (UL). (To find the DRIs and ULs, go to Health.com/links.) While most vitamins are listed in milligrams (mg) or micrograms (mcg), the label may use IUs (international units) for vitamins A, D, and E. The DRIs are 2,300 IUs for vitamin A, 200 for D, and 22 for E. What about the label’s % Daily Value column? Look at it with a skeptical eye: Those numbers haven’t been updated since 1968.

 

by Valerie Kramer Davis, Health Magazine July 2007