Sunday, October 07, 2007

Research looks at toddlers' sleep

Anyone who has cared for toddlers knows that many mysteries lurk in the 2- and 3-year-old brain. One of the biggest concerns their sleep.
How much do they need? Why does one child conk out at 7 p.m. while others are still playing outside? When and why will he stop napping? Does it matter if he skips the nap?
You won't find answers in the parenting books. Almost nothing is known about the biological processes that determine when and how much a preschooler sleeps, nor what happens when she doesn't sleep enough. That's because -- as anyone who has cared for a toddler can understand -- research on children this age is exceedingly difficult.
Fortunately for concerned parents and curious sleep scientists, Monique K. LeBourgeois has entered the breach.
A research professor at Brown University, LeBourgeois and two assistants have been visiting cooperative families in their homes, where they befriend the resident toddler, use games, books and toys to keep the little one awake, and measure the results. Their laboratory consists of portable file boxes and computer-stuffed backpacks; their skills include Play-Doh sculpture, nose-wiping and cuddling.
"It takes time and effort," LeBourgeois says. "You have to be in tune to the young kid."
With grants from the National Institute of Mental Health and drug-maker Sepracor, LeBourgeois is studying how skipping or delaying a nap -- they call it "nap deprivation" -- changes youngsters' behavior and emotions. As far as she knows, she's the first person ever to examine the question.
It's a crucial question. During the period from 2 to 5 years old, children's sleep patterns reorganize, making the transition from once-a-day napping to staying awake all day. At the same time, this is the period when they are learning some independence and self-control. Preschools and kindergartens are questioning whether to replace naptime with more learning. But does skipping a nap affect a child's ability to learn?
"(LeBourgeois's) research will give us the first peek into what's going on at this development stage with how the brain is trying to organize sleep," says Mary A. Carskadon, director of the Bradley Hospital Sleep and Chronobiology Research Lab, whose work on adolescents has made her one of the best-known sleep researchers in the country. "That will help us understand more about how parents should be viewing sleep and helping their children manage sleep at this young age."
Recently, LeBourgeois took her traveling sleep lab to a quiet neighborhood in Cranston, R.I., to visit 3-year-old Genevieve Steever. Genevieve had participated in a 25-day study last winter, and she's going to repeat the process a year later. The researchers wanted to reacquaint her with the procedures so she'll be at ease when the experiment resumes.
LeBourgeois' research assistant, Katherine G. Garlo, sat on the living room floor with blond-haired Genevieve. The little girl covered her face in a fit of shyness. "Do you want to sit on my lap?" Garlo asked her gently. Genevieve cried. "I want my mommy."
Her mother, Michelle Steever, rushed in and scooped her onto her lap. Genevieve was quickly soothed, and Garlo handed cotton rolls to the girl and her mother. "How do I do it?" Genevieve put the roll in her mouth and chewed it. So did her mother and Garlo. These, they reported, tasted like watermelon.
"Will you put it in the machine?" Garlo asked Genevieve. She dropped her cotton stick into a centrifuge the size of a microwave oven, and Garlo set it spinning. In a few seconds Garlo pulled out test tube containing about a teaspoon of spit. "Look how much you got!"
The saliva, collected on many occasions throughout the study, is analyzed for levels of the hormone melatonin. An increase in melatonin makes it easier to fall asleep and indicates that the brain's "clock" -- the internal system that regulates sleeping and waking _ is moving its hands toward nighttime. At other times, the saliva will be tested for levels of cortisol, a hormone released at times of stress.
Early results from the first 10 participants showed surprising variation in the time of day when melatonin levels started to rise. Some children's brains were ready for sleep as early as 6:15 or 6:30 p.m., while others went as late as 8:30. But all tended to have melatonin boosts at least two hours earlier than adults or adolescents.
On five days during the study, the researchers manipulate sleep times, by keeping the children stimulated with activities through naptime or past the usual bedtime. Then they put the children to sleep with electrodes attached to the scalp, face, shoulder and side.
How do you get a toddler to wear electrodes to sleep? With lots of practice. Genevieve Steever, who called the electrodes "sleep stickers," would wear them every night, even when there was no sleep study, her mother said.
When the researchers return in a few months, the sleep stickers will go live. They'll measure brain waves, eye movements, muscle activity and heartbeat while the child sleeps -- patterns that reveal the intensity of the body's "hunger" for sleep.
Another aspect of the study involves measuring children's emotional reactions after they've stayed awake through their naptime.
When Genevieve underwent her "nap deprivation," Michelle Steever remembers that she got "cranky and clingy."
But LeBourgeois has observed another, surprising phenomenon with the first few children in the study. Instead of the "tired and wired" meltdowns familiar to parents of napless toddlers, the children look quiet and sad, with blunted emotions. "They're not engaged; they're withdrawn," LeBourgeois says. For example, some gave up quickly on the puzzle. Others showed no delight at video scenes that would normally make them laugh or smile.
LeBourgeois has not yet analyzed her data, but she hopes the results will shed light on the role of sleep in emotional development. An estimated 7 to 23 percent of preschool children have emotional or behavioral problems.
Now, LeBourgeois is recruiting 10 more participants to complete her work.

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