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Studies show
consequences of sleep deprivation
(June 2008
Issue)
By Ami Albernaz
Anyone who spends time with children knows that lack of sleep can
wreak havoc on mood - first the child's and then perhaps the adult's
who is minding the child. And though adults are no better equipped
physiologically to deal with sleep deprivation, amassed responsibilities
render a full night's sleep more of a luxury. In recent years, studies
have hinted repeatedly at a hefty price for skimping on sleep.
The trouble seems to start in adolescence. Teenagers generally
need more sleep than younger children do - between nine and 10 hours.
Body clocks shift to later sleeping and waking times that are out
of synch with early school start times, says Amy Wolfson, Ph.D.,
associate professor of psychology at College of the Holy Cross in
Worcester, Mass.
"We're asking adolescents to clock in at school when they really
should be sleeping," she says. Melatonin, the hormone that peaks
at night and triggers sleep, might not yet have reached its lowest
level by the time students are working on English or Calculus. "That's
going to have an impact on their mood and how they perform," Wolfson
says.
With Mary Carskadon, Ph.D., director of the Chronobiology and Sleep
Research Laboratory at Bradley Hospital in East Providence, R.I.,
Wolfson studied the effects on middle schoolers of moving back
school start times. The two found that four times as many students
were tardy when the school day began at 7:15 a.m. compared to when
it began at 8:37 a.m. The two researchers found that mood also suffers
significantly.
"There's pretty convincing evidence from when you look at kids
with no history of depression," Wolfson says. "If you compare adolescents
who are getting an inadequate amount of sleep - 6.75 hours or less
- with those who are getting 8.25 or more, the ones getting less
have significantly higher incidences of depressed mood."
Sleep deprivation can also have insidious cognitive effects. In
a 2003 study by sleep researcher Hans Van Dongen, Ph.D., of Washington
State University, people who missed a couple of hours of sleep for
two weeks in a row performed as poorly on tests as did those who
stayed up two nights in a row, even though those in the former group
did not realize how impaired they were.
Inadequate sleep over a prolonged period may result in more serious
health consequences. Sleeping fewer than six hours a night is correlated
with increased risk of mortality, perhaps mediated by a number of
causes. People who sleep fewer than even seven hours a night seem
to have higher risk of heart disease, diabetes and obesity, says
Sanjay Patel, M.D., of the Pulmonary, Critical Care, and Sleep Medicine
at Case Western Reserve University.
"People who sleep less are more likely to have high blood pressure,"
Patel says. "Lab studies of short-term sleep deprivation suggest
that sympathetic nervous system activity may go up. Levels of leptin
(a hormone that controls appetite) go down.
People who sleep less also tend to exercise less, he adds. "They're
more likely to say, 'I'll take the elevator,' rather than the stairs."
While at Harvard Medical School a few years ago, Patel was involved
with the landmark Harvard Nurses' Health Study, which tracked, among
other things, duration of sleep of some 80,000 women. In that study,
those who slept fewer than six hours a night were at an increased
risk of death.
Patel and his colleagues have also observed a U-shaped curve when
it comes to sleep and mortality. Adults who sleep nine hours or
more a night also tend to die at higher rates.
While why this should be is unclear, long sleepers tend to drink
and smoke more and to exercise less, Patel says. They might also
have an illness, such as cancer, and be taking medication that makes
them sleepy. Not surprisingly, Patel and his colleagues have seen
a link between long sleep and depression, "which puts people at
a huge risk because they are not taking care of themselves.
So is there a set amount of sleep each of us should be getting
each night? While Patel acknowledges that individual needs vary,
he believes seven hours is the minimum.
"This is from a medical perspective," he adds. "Some studies suggest
that the brain might function better with eight or nine hours."
If you're wondering who has time for eight or nine hours of sleep
each night, you just might be proving true another of Patel's beliefs.
"I do think people tend to underestimate how important sleep is
for them," he says.
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