Every animal sleeps,
but why the brain needs sleep has remained a mystery. Neuroscientists
now believe sleep is not only crucial to brain development, but
is also necessary to help consolidate the effects of waking experience – by
converting memory into more permanent and/or enhanced forms.
Sleeping problems are
almost always involved in mental disorders, including depression,
schizophrenia, Alzheimer's disease, stroke, as well as head injury.
And symptoms are strongly influenced by the amount of sleep a
person gets. Difficulties may arise from the drugs used to control
symptoms of a disorder, or from changes in the brain regions
and neurotransmitters that control sleep.
Sleep
and Stress Topics:
Stress, Behavior and Sleep
The Effects of Snoring
How Sleep Benefits Brains
|
|
|
The
Effects of Sleep Deprivation |
|
|
|
|
Adequate sleep
is crucial to proper brain function – no less
so than air, water, and food – but stress can
modify sleep-wakefulness cycles.
Any amount
of sleep deprivation will diminish mental performance,
cautions Mark Mahowald, a professor of neurology at
the University of Minnesota Medical School. "One
complete night of sleep deprivation is as impairing
in simulated driving tests as a legally intoxicating
blood-alcohol level."
|
|
At the American
Diabetes Association's annual meeting in June 2001,
Eve Van Cauter, Ph.D., reported that people who regularly
do not get enough sleep can become less sensitive to
insulin. This increases their risk for diabetes and
high blood pressure – both serious threats to
the brain.
Previous work
by Dr. Van Cauter, a professor of medicine at the University
of Chicago, found that "metabolic and endocrine
changes resulting from a significant sleep debt mimic
many of the hallmarks of aging. We suspect that chronic
sleep loss may not only hasten the onset but could
also increase the severity of age-related ailments
such as diabetes, hypertension, obesity, and memory
loss ."1
topics
|
|
|
Stress
Hormones and Insomnia-Study |
|
|
|
That stress
can affect proper sleep seems obvious, but researchers
at Pennsylvania State University College of Medicine
have found another reason why middle-aged men may be
losing sleep. It's not just because of what they worry
about. Rather, it's due to "increased vulnerability
of sleep to stress hormones," according to Dr.
Alexandros N. Vgontzas.
As men age,
it appears they become more sensitive to the stimulating
effects of corticotropin-releasing hormone (CRH). When
both young and middle-aged men were administered CRH,
the older men remained awake longer and slept less
deeply. (People who don't get enough of this "slow-wave" sleep
may be more prone to depression.) |
|
"The
increased prevalence of insomnia in middle-age may,
in fact, be the result of deteriorating sleep mechanisms
associated with increased sensitivity to arousal-producing
stress hormones, such as CRH and cortisol," Vgontzas
and colleagues suggest.2
In another
study, the researchers compared patients with insomnia
to those without sleep disturbances. They found that "insomniacs
with the highest degree of sleep disturbance secreted
the highest amount of cortisol , particularly in the
evening and nighttime hours," suggesting that
chronic insomnia is a disorder of sustained hyperarousal
of the body's stress response system.3
topics
|
|
|
Stress
and Sleep Patterns-Study |
|
|
|
Why do some
people lose sleep during periods of stress, while others
seem to "sleep like a baby"? Research suggests
that the difference may be explained by the ways people
cope.
At Tel Aviv
University, Dr. Avi Sadeh conducted a study of students.
He found that those "who tended to focus on their
emotions and anxiety during the high-stress period
were more likely to shorten their sleep, while those
who tended to ignore emotions and focus on tasks extended
their sleep and shut themselves off from stress." |
|
The researchers
think that "stress may take the During a routine
week of studies, and again during a highly stressful
month, sleep patterns of 36 students
(aged 22 to 32) were
documented. Sleep quality
improved or remained the same for students who directed their focus away
from their emotions, but diminished for those who fretted and brooded as
a way to
cope with stress.
Almost titling
his paper, "If you can't cope with it, sleep on
it," Sadeh said "sometimes sleep can help
you regulate your nervousness and offer you an escape
from stress, particularly when there's nothing you
can do about it."4
topics
|
|
|
Children’s
Sleep Patterns Related to Behavior-Study |
|
|
|
A Northwestern
University study of 500 preschoolers found that those
who slept less than 10 hours in a 24-hour period (including
daytime naps) were 25% more likely to misbehave. They
were consistently at greatest risk for "acting
out" behavioral problems, such as aggression and
oppositional or noncompliant behavior.5
|
|
Research shows
that sleep disturbances in children are not only associated
with medical problems (allergies, ear infections, hearing
problems), but also with psychiatric and social issues.
Children who were aggressive, anxious, or depressed
had more trouble falling and staying asleep. Although
sleep problems usually decline as children get older,
these early patterns are the best indicator of future
sleep troubles.6
topics
|
|
|
|
|
What
is Sleep Apnea? |
|
|
|
|
A serious
concern for the brain is obstructive sleep apnea, a
disorder of interrupted breathing when muscles relax
during sleep. It usually occurs in association with
fat buildup or loss of muscle tone with aging.
During an
episode of obstructive apnea, the person's effort to
inhale air creates suction that collapses the windpipe.
This blocks the air flow for ten seconds to a minute,
while the sleeping person struggles to breathe. When
the blood oxygen level falls, the brain responds by
awakening the person enough to tighten the upper airway
muscles and open the windpipe. The person may snort
or gasp, then resume breathing – a cycle repeated
hundreds of times a night. |
|
Frequent
awakenings due to sleep apnea may lead to personality changes such as irritability
or depression, and because it also deprives the person of oxygen,
it can lead to a decline in mental functioning and an increased risk of stroke
or heart attack.
Loud snoring
and excessive daytime sleepiness are symptoms of sleep
apnea, but not everyone who snores has this disorder.
Also, frequent morning headaches may be a sign of sleep
apnea. topics
|
|
|
Adult
Snorers at Risk for Stroke-Study |
|
|
|
Researchers
evaluated 1,348 adults for the association between
the risk of getting a stroke with snoring, sleep duration,
and daytime drowsiness. Even after taking classic risk
factors into consideration – age, race, gender,
cigarette smoking, high cholesterol, high blood pressure,
diabetes – the risk for stroke was independently
and significantly associated with sleep factors.
|
|
"We found
that certain sleep characteristics such as sleeping
for more than eight hours, the tendency to fall asleep
during the day, and the tendency to snore influence
the likelihood of having a stroke," says the study's
lead author Adnan I. Qureshi, M.D., assistant professor
of neurosurgery at the State University of New York
at Buffalo. "Individuals who snore severely or
have trouble staying awake during the day should see
a doctor to find out why."7
topics
|
|
|
Snoring
Children and Intellectual Potential-Research |
|
|
|
|
"Snoring
should always be considered a problem, since snoring
indicates the presence of increased upper airway resistance
during sleep," says Dr. David Gozal, a researcher
at the University of Louisville.
Gozal and
his colleague Dennis W. Pope Jr. interviewed more than
1,500 middle-school students. About 13% of those ranking
in the bottom quarter of their class reported loud
and frequent snoring in early childhood, compared to
only 5% in the top quarter. Half the loud snorers lived
with adults who smoked.
The disordered
breathing – and disrupted sleep – associated
with snoring can lead to attention-deficits and hyperactivity,
asthma and allergies, as well as aggression, the investigators
found. Because these problems can adversely affect
academic performance, snoring can be considered a serious
threat to a child's intellectual potential. |
|
"These
findings suggest that children who experienced sleep-disordered
breathing during a period traditionally associated
with major brain growth and substantial acquisition
of cognitive and intellectual capabilities may suffer
from a partially irreversible compromise of their.
. . potential for academic achievement," reported
the researchers.
Gozal believes "that
the presence of frequent and loud snoring in children
who also demonstrate behavioral problems, learning
problems, bedwetting, or failure to thrive, should
prompt referral to a primary care physician and strong
consideration of an evaluation by a pediatric sleep
specialist."8
topics
|
|
|
Snoring
and ADHD-Study |
|
|
|
Dr. David
Gozal, a researcher at the University of Louisville,
found a connection between snoring and attention-deficit/hyperactivity
disorder (ADHD) in some young children. After collecting
data on more than 5,000 six-year-olds, and surveying
the parents of 11,000 first-graders, he and his team
found that twice as many ADHD children experienced
frequent loud snoring, compared to the general population
of children. An even greater risk factor than parents's
snoring habits was exposure to secondhand smoke at
home.
|
|
When he treated
kids for their snoring, their ADHD became much better
or totally disappeared, says Gozal. Even if it did
not lead to complete resolution, there was some improvement
in behavior and less need for medication.9
In an Italian
study of more than 2,200 children, the group with the
highest body mass index (BMI) was more than twice as
likely to snore, compared to the group with the lowest
BMI (a measurement of weight in relation to height).10
topics
|
|
|
Gravity
and Snoring-Study |
|
|
|
Because the
respiratory system is greatly influenced by the force
of gravity, the effect of weightlessness on sleep-related
breathing problems was observed in five space shuttle
astronauts. Dr. G. Kim Prisk from the University of
California at San Diego found that, without gravity,
breathing problems were reduced by 55% – and
snoring was nearly eliminated.
|
|
His report
suggests that obstructed breathing might be alleviated
by sleeping in a more upright position, instead of
on the back.11
topics
|
|
|
|
|
Sleep
Enhances Brain Connections in Early Development-Study |
|
|
|
Animal studies
show that sleep dramatically enhances changes in
brain connections during a period of early development.
Researchers at the University of California, San
Francisco, examined the effect of sleep on brain
plasticity in young cats that had just experienced
an environmental challenge. The animals that were
allowed to sleep for six hours after the stimulation
developed twice the amount of brain change, compared
to cats kept awake afterward.
"This
is the first direct evidence that sleep modifies
the effect of environmental stimuli on the development
of new brain connections," said Marcos G. Frank,
Ph.D. The finding has broader implications for plasticity
in the brains of adult animals and people. |
|
"I
think it's likely to be true that other areas of
the brain, higher areas of the brain, have their
critical (developmental) periods later in life," said
the study's senior author Michael P. Stryker, Ph.D., "and
some of them, in the highest areas, the critical
periods never close until senility."12
What's more,
the amount of plasticity (connections between nerve
cells) in the brain depends on the amount of deep
sleep, which is indicated by large slow brain waves.
This is the sleep that a person falls into when they
first go to sleep, and accounts for half of sleep
time in young animals and human babies, (who get
up to three times more sleep than adults). Stryker
said this is precisely the time in life when the
brain reorganizes its connections to attain the perfect
precision it needs as an adult.
topics
|
|
|
A
Better Way to Prepare for Exams |
|
|
|
|
Sleep could
prove to be an important part of the strategy for
preparing for challenges such as exams. "The
fact that sleep provoked slightly more plasticity
(connections between nerve cells) than double the
amount of exposure to experience – suggests
that if you reviewed your notes thoroughly until
you were tired and then slept, you'd achieve as much
plasticity, or 'learning,' in the brain as if you'd
pulled an all-nighter repeating your review of the
material," says Michael P. Stryker, Ph.D., researcher
at the University of California, San Francisco
|
|
Studies
have shown that sleep-loss affects learning and memory.
When animals and humans are deprived of sleep, they
do not perform
well on memory tasks.
topics
|
|
|
REM
Sleep Enhances Emotional Memory-Study |
|
|
|
Human research
supports the function of rapid eye movement (REM) sleep
in memory formation. German scientists at the University
of Bamberg Department of Physiological Psychology compared
memory retention of emotional versus neutral text material.
Participants were tested over intervals covering either
early sleep (dominated by slow wave sleep) or late
sleep when REM sleep is dominant.
|
|
Sleep not
only improved retention, compared to a wake group,
but "late sleep particularly enhanced memory for
emotional texts. This effect was highly significant
in comparison with memory for neutral t
| | | |