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any parent of a teenager knows, rousing a sleeping adolescent can be, to put
it mildly, difficult. Grumpy and monosyllabic until later in the day,
it can be just as much of a struggle to get your teen to go to bed at night,
what with homework, instant messaging, email and general late-night wakefulness.
On the weekends, the door to the 'Bat Cave' remains shut until the crack of
noon -- or even later -- while everyone else in the family, up for hours, goes
about their business.
Should you be concerned about this antisocial rite of passage? Or is there
something more to your adolescent's sleep habits?
Relax. There is good news. Landmark studies into the adolescent brain have
revealed that the contrariness of a teen's biorhythms are in fact just what
nature intended. According to Dr. Jay Giedd, chief of brain imaging at the Child
Psychiatry Branch of the National Institute of Mental Health (NIMH) in Bethesda,
MD, and colleagues at the University of California at Los Angeles (UCLA) as
well as at McGill University in Montreal, daytime sleepiness and late-night
alertness are the result of a shift in the sleep/wake cycle as growth hormones
kick into high gear. Beginning in 1991, they used magnetic resonance imaging
(MRI) to study brain growth in 1,000 children every two years from the age of
3 to 18 years. They found that during the night, growth hormone is released
during Rapid Eye Movement (REM) or "dream sleep," which takes place
at the end of each sleep cycle. "One of parents' early observations,"
notes Dr. Roger Tonkin, a Vancouver pediatrician and adolescent health care
specialist, "is that the kid who used to jump out of bed now has to be
hauled out just to get on school on time."
Importantly, it's not just your teen's shoe size that's getting bigger. His
or her brain is also growing. While it has been well documented that 95% of
brain development takes place by the age of five years, the NIMH study, which
was conducted over a nine-year period, indicates that there is a second wave
of brain growth, particularly in the prefrontal cortex or "thinking"
part of the brain, which continues into the teen years and even into the 20s.
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What's so
special about REM sleep?
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Even those people notorious
for tossing and turning all night are absolutely motionless during Rapid
Eye Movement (REM) sleep or "dream" sleep. According to sleep
researcher Carlysle Smith, professor of psychology at Trent University in
Peterborough, Ontario, "There is absolutely no muscle movement possible;
you are absolutely paralyzed."
Except, of course, for your eyes. During REM sleep, special electrical activity
emanating from the brain stem floods the rest of the brain, causing the
eyes to move back and forth under closed eyelids. The more learning that
has occurred before you went to sleep, the more intense -- and rapid --
the eye movements during this stage of sleep, Dr. Smith and colleagues have
found.
"We looked at students after they had finished an exam versus after
they had finished just another day of school," he explains. "After
an exam, we saw massive increases in the number of eye movements, which
reflect this special brainstem activity."
Most recently, collaboration with researchers in Belgium who are using a
PET (Positive Electron Tomography) scan to study brain activity has revealed
that if a particular area of the brain is active during the learning of
a task when the subject is awake, then it is especially active when the
subject goes to sleep, during REM sleep. A coincidence? Dr. Smith thinks
not. "We think that the neurons are doing further memory processing
in some way," he explains. |
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During this time, new brain cells and neural connections or "wires" which connect
the right and left sides of the brain and are critical to intelligence, self-awareness
and performance, grow like branches on a tree. Daytime stimulation, in the form
of school and social interaction, gets "hard-wired" into the adolescent brain
during the latter stages of sleep, including REM sleep.
Cut these sleep stages short and performance suffers the next day, says Dr.
Carlysle Smith, professor of psychology at Trent University in Peterborough,
Ont. "If you want to learn really well and to be really efficient in your
learning, the best way to do it is to get a good night's sleep," he says.
For the past 30 years, Dr. Smith and colleagues have pioneered research into
sleep deprivation and performance in people 18-24 years of age. Their studies
in young college students 18 to 24 years of age attending Trent University show
that when you teach people new tasks and then deprive them of REM sleep, test
scores go down. What's more, Dr. Smith suspects this effect, particularly in
certain kinds of memory that is sensitive to sleep loss, may be even more dramatic
in younger students. "Kids in grade school should be getting 9 or 10 hours
a night," he says. "If they're not, they're probably not learning
all that well."
Most teens probably need about 9.5 hours of sleep, say experts, but the reality
of a typical teen life -- early morning soccer or swim practice, homework and
perhaps a part-time job after school -- means that most are lucky to get 7-1/2
hours. Chronic sleep deprivation can affect mood and make it difficult for a
teen to perform or even react appropriately.
Since the amount of sleep everyone needs for optimum performance is very individual,
how do you tell if your teen is getting enough sleep to live up to his or her
learning potential? Dr. Tonkin suggests that while some teens seem to be able
to cope with chronic sleep deprivation, others become irritable and apathetic.
The treatment? Let him or her sleep whenever they can, including the weekends.
If your teen wants to sleep until noon on Saturday, advises Dr. Tonkin, "let
him."
However, catching up on sleep on the weekend, while perfectly normal for most
teens, may not help learning, warns Dr. Smith. "If you learn something
on Tuesday and are short of sleep until Saturday, it's too late," he explains.
"You've got to get it the same night."
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