Too much, too little sleep tied to ill health in CDC study

ATLANTA (AP) -- People who sleep fewer than six hours a night -- or more than nine -- are more likely to be obese, according to a new government study that is one of the largest to show a link between irregular sleep and big bellies.

The study also linked light sleepers to higher smoking rates, less physical activity and more alcohol use.

The research adds weight to a stream of studies that have found obesity and other health problems in those who don't get proper shuteye, said Dr. Ron Kramer, a Colorado physician and a spokesman for the American Academy of Sleep Medicine.

''The data is all coming together that short sleepers and long sleepers don't do so well,'' Kramer said.

The study released Wednesday is based on door-to-door surveys of 87,000 U.S. adults from 2004 through 2006 conducted by the National Center for Health Statistics, part of the Centers for Disease Control and Prevention.

Such surveys can't prove cause-effect relationships, so -- for example -- it's not clear if smoking causes sleeplessness or if sleeplessness prompts smoking, said Charlotte Schoenborn, the study's lead author.

It also did not account for the influence of other factors, such as depression, which can contribute to heavy eating, smoking, sleeplessness and other problems.

Smoking was highest for people who got under six hours of sleep, with 31 percent saying they were current smokers. Those who got nine or more hours also were big puffers, with 26 percent smoking.

The overall U.S. smoking rate is about 21 percent. For those in the study who sleep seven to eight hours, the rate was lower, at 18 percent.

Results were similar, though a bit less dramatic, for obesity: About 33 percent of those who slept less than six hours were obese, and 26 percent for those who got nine or more. Normal sleepers were the thinnest group, with obesity at 22 percent.

For alcohol use, those who slept the least were the biggest drinkers. However, alcohol use for those who slept seven to eight hours and those who slept nine hours or more was similar.

In another measure, nearly half of those who slept nine hours or more each night were physically inactive in their leisure time, which was worse even than the lightest sleepers and the proper sleepers. Many of those who sleep nine hours or more may have serious health problems that make exercise difficult.

Many elderly people are in the group who get the least sleep, which would help explain why physical activity rates are low. Those skimpy sleepers who are younger may still feel too tired to exercise, experts said.

Stress or psychological problems may explain what's going on with some of the lighter sleepers, experts said.

Other studies have found inadequate sleep is tied to appetite-influencing hormone imbalances and a higher incidence of diabetes and high blood pressure, noted James Gangwisch, a respected Columbia University sleep researcher.

''We're getting to the point that they may start recommending getting enough sleep as a standard approach to weight loss and the prevention of obesity,'' said Gangwisch, who was not involved in the study.

For more information, just click
- National Center for Health Statistics: http://www.cdc.gov/nchs
- American Academy of Sleep Medicine: http://www.aasmnet.org/

By THE ASSOCIATED PRESS

Memory Training Shown to Turn Up Brainpower

A new study has found that it may be possible to train people to be more intelligent, increasing the brainpower they had at birth.

Until now, it had been widely assumed that the kind of mental ability that allows us to solve new problems without having any relevant previous experience — what psychologists call fluid intelligence — is innate and cannot be taught (though people can raise their grades on tests of it by practicing).

But in the new study, researchers describe a method for improving this skill, along with experiments to prove it works.

The key, researchers found, was carefully structured training in working memory — the kind that allows memorization of a telephone number just long enough to dial it. This type of memory is closely related to fluid intelligence, according to background information in the article, and appears to rely on the same brain circuitry. So the researchers reasoned that improving it might lead to improvements in fluid intelligence.

First they measured the fluid intelligence of four groups of volunteers using standard tests. Then they trained each in a complicated memory task, an elaborate variation on Concentration, the child’s card game, in which they memorized simultaneously presented auditory and visual stimuli that they had to recall later.

The game was set up so that as the participants succeeded, the tasks became harder, and as they failed, the tasks became easier. This assured a high level of difficulty, adjusted individually for each participant, but not so high as to destroy motivation to keep working. The four groups underwent a half-hour of training daily for 8, 12, 17 and 19 days, respectively. At the end of each training, researchers tested the participants’ fluid intelligence again. To make sure they were not just improving their test-taking skills, the researchers compared them with control groups that took the tests without the training.

The results, published Monday in The Proceedings of the National Academy of Sciences, were striking. Although the control groups also made gains, presumably because they had practice with the fluid intelligence tests, improvement in the trained groups was substantially greater. Moreover, the longer they trained, the higher their scores were. All performers, from the weakest to the strongest, showed significant improvement.

“Intelligence has always been considered principally an immutable inherited trait,” said Susanne M. Jaeggi, a postdoctoral fellow in psychology at the University of Michigan and a co-author of the paper. “Our results show you can increase your intelligence with appropriate training.”

Why did the training work? The authors suggest several aspects of the exercise relevant to solving new problems: ignoring irrelevant items, monitoring ongoing performance, managing two tasks simultaneously and connecting related items to one another in space and time.

No one knows how long the gains will last after training stops, Dr. Jaeggi said, and the experiment’s design did not allow the researchers to determine whether more training would continue to produce further gains.

By NICHOLAS BAKALAR