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Renew - Sleep and Stress

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

Stress, Behavior and Sleep

Many of us know what it is like to go without sleep and how it can effect our mood and stress level. Here you will find important information about why you may be losing sleep and intriguing studies about sleep deprivation. You may be surprised.

 
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

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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

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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

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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

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The Effects of Snoring

In our society, snoring is often viewed as a comic nuisance. Couples complain of partners keeping them awake, the kids will laugh at grandpa snoring away during an afternoon nap, and if you are the one who kept everyone awake during a group sleepover, you’re sure to hear about the next morning. The fact is snoring can create serious problems for the brain and even intellect. Curious? Check out the particulars behind snoring.

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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.

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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

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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

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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

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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

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How Sleep Benefits Brains

Ah-h-h. There is nothing like a good night’s sleep. You feel refreshed and ready for the day. But did you know that during sleep you are enhancing your learning and memory? Did you know that you would probably do better on an exam if you had a good night’s sleep versus pulling an all-nighter? Find out more about the surprising benefits of sleep and how you can make the most out of those blissful hours.

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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.

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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.

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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 texts," said the authors. "Results are consonant with a supportive function of REM sleep predominating late sleep for the formation of emotional memory in humans."13

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REM Sleep and Learning-Study

After reviewing the existing research on sleep, dreams, learning, and memory, Dr. Robert Stickgold and his colleagues at Harvard Medical School concluded that REM sleep seems to be essential for learning how to do things. Learning to play a musical instrument is an example of such "procedural learning."

Decision-making also appears to benefit from this overnight form of cogitation. During sleep, particularly the REM phase, the brain integrates information it took in during the day but couldn't process at the time. "Sleeping on it" is not necessary, however, for simple memory or learning tasks.

 

Stickgold also believes that sleep may be involved in "erasing memories from the immediate and distant past," and that dreaming is probably a piece of this process.14

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Activating Memory in Sleep-Study

Earlier studies with rodents, birds, and humans have suggested that brain activity initiated while awake is later reactivated during subsequent sleep, as part of the process that consolidates recent experience into memory.

Scientists at Rockefeller University showed that, in rats, certain brain cells that activate during daytime exploration tend to reactivate during sleep. Sidarta Ribeiro, Constantine Pavlides, and colleagues found that exposure to a "memorable" environment causes the brain to turn on a gene called zif-268 that is associated with strengthened communication between nerve cells.

The researchers exposed a group of rats to novel, enriched environments (labyrinths with toys), and another group of rats to their normal home cages. Then the rats went to sleep, passing through successive stages of slow wave and REM sleep.

 

During slow wave sleep, zif-268 turned off in all rats, regardless of which environment they had experienced. But during REM sleep, zif-268 turned on in the cerebral cortex and hippocampus of only rats that had explored the labyrinths. The gene stayed off in rats that had not experienced the enriched environments.

This retrieval of zif-268 activity during REM sleep may couple with other reactivated brain mechanisms to "process" memories of novel experiences. Such processing may in turn prove important for cementing the memories acquired while awake.15

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Napping-Study

Why do cats nap? Because they can. But so can you. Simply taking a nap may be one of the best things you can do to correct poor mental performance, especially after a stressful night of disrupted sleep, such as from sleep apnea or snoring . Naps can help make up for nighttime loss.

 

In a study of Japanese men, a mid-afternoon nap had positive effects upon the maintenance of their daytime vigilance level. The 20-minute nap improved performance level and their self-confidence.16

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