Monday, November 11th, 2013
Children who don’t get an adequate amount of sleep each night may be at higher risk of obesity, according to a new study published in the journal Pediatrics. More from The New York Times:
Researchers randomly divided 37 children aged 8 to 11 into two groups. Each group increased their habitual time in bed by an hour and a half per night for one week, then decreased their time by the same amount the next week. They wore electronic devices to measure sleep time, were assessed for daily food intake three times a week, and had blood tests to measure leptin, a hormone that affects hunger, and high levels of which correlate with fat tissue accumulations.
Children consumed 134 calories fewer each day during the increased sleep week than the during the week with less sleep. Fasting leptin levels were lower when the children slept more and, over all, the children’s weight averaged about a half pound less at the end of long sleep weeks than short ones.
Image: Child eating, via Shutterstock
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Wednesday, September 25th, 2013
Children who take naps are better able to process and retain new information in the classroom, according to a new study by researchers at the University of Massachusetts Amherst. More from The Boston Globe:
In a study of 40 preschoolers, napping aided children’s ability to recall information they had been taught earlier that day. Children recalled 75 percent of the matches accurately after a nap, versus 65 percent when they skipped a nap.
“There was very little telling us about naps, the physiology of them— nothing to say they really had a function,” said Rebecca Spencer, an associate professor of psychology and neuroscience at UMass Amherst. “I think policy-wise, teachers, in order to make the most of the research, need to know more about how to promote napping in the classroom.”
In the study, published in the Proceedings of the National Academy of Sciences on Monday, researchers taught children a game that resembled the popular game Memory, in which children have to match images with cards laid out in a grid pattern. They chose the memory task because it requires many of the basic skills preschoolers utilize when attempting other types of learning, such as learning the alphabet.
After playing the game, the children either napped or stayed awake. Later that afternoon, they were tested again, to see how much they remembered from the morning session.
A week later, the experiment was flipped. The children who had napped in the first experiment were kept awake, and those who had not slept.
The difference was clear, Spencer said, with those who napped recalling 10 percent more of the locations of the cards than when they did not nap. The researchers even checked the children the next day to see if overnight sleep had an effect, and found no difference in performance.
Spencer then brought some of the children into the laboratory and measured their brain activity while they slept. To her surprise, she found that the kids were not experiencing REM sleep associated with dreaming. She did, however, detect bursts of brain activity called sleep spindles that were associated with the most productive naps—the ones that helped children retain memory. In other studies, that type of brain activity had been associated with moments when the brain was most plastic and adaptable.
The study clearly suggests that napping may be a potent part of the learning process, but there was an interesting anomaly. Among children who were not habitual nappers, sleeping did not have an effect. That suggests to Spencer that as the children’s brains mature, perhaps they do not depend on the nap to consolidate their memories.
Image: Napping preschooler, via Shutterstock
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Tuesday, July 9th, 2013
Children who go to bed at the same time every night–even if that time is a little later than parents think they need–may get a boost in school performance and brain development, according to a new study published in the Journal of Epidemiology and Community Health. More from CNN:
“If the child prefers to go to sleep a little bit later, but it’s done regularly, that’s still OK for them, according to the evidence,” said Amanda Sacker, professor in the Department of Epidemiology and Public Health at University College London.
Researchers looked at information about bedtimes and standardized test scores for more than 11,000 children who were part of the UK Millennium Cohort Study, a nationally representative study of children in the United Kingdom.
The Millennium Cohort Study followed children when they were aged 3, 5 and 7, and included regular surveys and home visits. Researchers asked parents about family routines such as bedtimes.
Children also took standardized tests in math, reading and spatial abilities when they were 7 years old.
Researchers controlled for socioeconomic status in addition to other factors such as discipline strategies, reading to children and breakfast routines.
The study found that, in general, consistent bedtimes were linked to better performance across all subject areas. This was especially true for 7-year-old girls, regardless of socioeconomic background – they tended to do worse on all three intellect measurements if they had irregular bedtimes. Boys in this age group did not show the effect.
In both girls and boys, non-regular bedtimes at age 3 were linked with lower test scores, but not at age 5.
Bedtimes that had never been consistent for girls at ages 3, 5, and 7 were associated with lower scores than regular bedtimes. For any two of these ages, boys also tended to do worse on the tests if they didn’t go to sleep at a routine time.
These results “showed that it wasn’t going to bed late that was affecting child’s development, it was the irregular bedtimes that were linked to poorer developmental scores,” Sacker said.
Image: Boy at bedtime with clock, via Shutterstock
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Wednesday, April 17th, 2013
Advising pregnant women in poor and developing countries to sleep on their sides might help lower the rate of stillborn children by at least 25 percent, according to a new study conducted in Ghana. More from The New York Times:
A graduate student’s summer project, the study is relatively small — it included only 220 women interviewed about their sleep habits just after giving birth in one hospital in Ghana.
But because Ghana has such a high rate of stillbirth, said Louise M. O’Brien, the professor at the University of Michigan’s Sleep Disorders Center who oversaw the project, by Jocelynn Owusu, the conclusion seemed clear: If pregnant women avoid sleeping on their backs, 25 percent of all stillbirths in poor countries might be prevented.
The study, published online last month by The International Journal of Gynecology & Obstetrics, also found that loud snoring — which is worsened by back (supine) sleeping — raised the likelihood that a pregnant woman would get high blood pressure, a condition that may lead to a complication known as pre-eclampsia, which can kill both mother and child if left untreated or not stopped by Caesarean section.
The Ghanaian study echoed one conclusion drawn from larger studies in the United States and New Zealand, Dr. O’Brien said: that apnea in pregnant women raises blood pressure and increases risk to the baby.
The leading theory, she said, is that when a heavily pregnant woman sleeps on her back, the uterus compresses the vena cava, the blood vessel going up the spine that returns blood to the heart. That starves the fetus, leading to smaller babies and more stillbirths. Supine sleeping also closes the airways, leading to oxygen deprivation, which raises blood pressure. Closed airways lead to snoring.
“In the delivery room, when an obstetrician sees a baby in distress, they often flip the woman on to her side,” Dr. O’Brien said. “But people haven’t thought through the connection to the months prior to delivery.”
In wealthy countries, blood pressure is lowered with drugs and apnea is prevented with breathing machines. But the drugs are little used in Africa and the machines are too costly.
Image: Pregnant woman sleeping on her side, via Shutterstock
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Friday, March 29th, 2013
While babies’ and toddlers’ brains are developing and changing in sporadic and intense ways, teenagers may be consistently experiencing their brain development while they’re asleep, according to a new study by researchers at the University of California at Davis has found. More from The Washington Post:
While babies, toddlers and young children are taking in and making sense of the world, their brain cells are wiring themselves together willy-nilly, creating super-dense networks of interwoven neurons. But as we reach and progress through adolescence, neuroscientists have observed, a period of intensive “synaptic pruning” occurs in which those networks are thinned and the strongest and most evolutionarily useful remain.
In a study published last week, scientists from the University of California at Davis say they believe the slowed fluctuations observed during the delta phase of teens’ sleep may be evidence of that pruning process at work.
And since major mental illnesses such as schizophrenia appear to take root during adolescence, the authors of the study say the changing architecture of sleep may offer clues as to how and when mental illness sets in.
Image: Sleeping teenager, via Shutterstock
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