Post
Monday, May 9, 2005; A07

Babies, Adults Sleep Similarly

Any parent can tell you there are differences between how adults and infants sleep.

A baby who is babbling one minute can be sleeping soundly the next.

Newborns often sleep more than 16 hours a day. Normal adults usually sleep half that, or less.

Fifty percent of babies' sleep is spent in a stage characterized by rapid eye movement (REM) indicating brain activity, a lack of overall muscle tone and occasional twitching. Adults spend about 20 percent in REM sleep.

Although an electroencephalogram can indicate when the brain's neurons are firing as adults cycle in and out of the two broad stages of sleep, an EEG shows little activity in the cerebral cortex of a sleeping baby.

Because of that, scientists long believed that infants' sleep is primitive and without stages. However, a study by researchers at the University of Iowa indicates that babies and adults do not sleep so differently after all.

Mark Blumberg, of the research team that published results this month in the online journal PLoS Biology, said infants and adults have the same basic stages of sleep. As babies grow, he said, "it's more that the pattern of sleep is changing over time."

Through a series of tests on week-old rats, the researchers linked behaviors that indicate REM and non-REM sleep to specific midbrain areas also known to be crucial in the sleep of adults. From this, they concluded that the neural mechanisms of infant and adult sleep are very similar.

For the 40 million American adults who suffer from sleep disorders, such research might one day help them to sleep like babies.

-- Susan P. Williams

When and where power plants emit nitrogen oxide can make a huge difference in the health effects of air pollution, a new study finds.

Measuring emissions from a power plant in eastern Pennsylvania in July 1995, Princeton University scientists found that a given amount of nitrogen oxide produced much more ground-level ozone on warmer days than on cooler ones. On hot days, they calculated, emissions from a plant upwind of a densely populated area could lead to more than three times as many deaths as in cool weather.

Denise L. Mauzerall, lead author of the study published in the May issue of the journal Atmospheric Environment, said the findings were significant in light of the Bush administration's plans for a "cap and trade" program for power plant emissions in the eastern United States. The Clean Air Interstate Rule finalized in March aims to cut overall nitrogen oxide emissions from utilities by 61 percent in the next decade, but missions from individual plants may vary widely.

"When and where [emissions take place] makes a big difference in how much damage is done," Mauzerall said in an interview.

Utilities lobbyist Scott Segal said an approach that sought to minimize emissions at particular times would penalize plants that "have to operate 24 hours a day, seven days a week, 365 days a year."

"A rule like that would hit ratepayers really, really hard," he said, adding that utilities have to produce more electricity in summer to meet air conditioning needs.

-- Juliet Eilperin

Ever wonder why children can't hit the softball or tennis ball even when you throw it oh so slowly?

It is easy to understand, vision scientist Terri Lewis said. "Kids can't judge slow speeds. They can't tell that the ball's moving at all." The solution: "Give it a little more oomph. They'll do better."

Lewis, of Canada's McMaster University, in Hamilton, Ontario, studied the reactions of adults and 5-year-olds as they watched sets of lines moving laterally across a computer screen and tried to guess which set was moving faster.

"Adults aren't particularly good with slow speeds," Lewis said in a telephone interview. "But kids are three times worse." The research is to be published in the July issue of the journal Vision Research.

Lewis said the human brain, at any age, does not have very many neurons to deal with anything in slow motion, and the shortcoming is dramatically worse in the brain of a child. It works with lateral movement and movement toward and away from the viewer.

This, Lewis said, is why kids swing erratically when Dad throws the tennis ball and might not swing at all when he throws it more slowly. It is why the baseball bounces off the kid's catcher's mitt, why the kid looks at you for instructions instead of at the ball, and why it doesn't help if you yell "Now!"

-- Guy Gugliotta