Sleep Twitches “Light Up” the Brain


A University of Iowa study has found twitches made during sleep activate the brains of mammals differently than movements made while awake. Researchers say the findings show twitches during rapid eye movement (REM) sleep comprise a different class of movement and provide further evidence that sleep twitches activate circuits throughout the developing brain. In this way, twitches teach newborns about their limbs and what they can do with them.


UI graduate students Alexandre Tiriac and Carlos Del Rio-Bermudez say the findings of their new study provide further evidence that newborns learn about their bodies by twitching in their sleep.


“Every time we move while awake, there is a mechanism in our brain that allows us to understand that it is we who made the movement,” says Alexandre Tiriac, a fifth-year graduate student in psychology at the UI and first author of the study titled “Self-Generated Movements with “Unexpected” Sensory Consequences“, which appeared this month in the journal Current Biology. “But twitches seem to be different in that the brain is unaware that they are self-generated. And this difference between sleep and wake movements may be critical for how twitches, which are most frequent in early infancy, contribute to brain development.”


Mark Blumberg, a psychology professor at the UI and senior author of the study, says this latest discovery is further evidence that sleep twitches— whether in dogs, cats or humans—are connected to brain development, not dreams.

“Because twitches are so different from wake movements,” he says, “these data put another nail in the coffin of the ‘chasing rabbits’ interpretation of twitches.”


According to UI reporter Sara Agnew, researchers record no brain activity when a baby rat vigorously moves its left hindlimb while awake. While the left hindlimb of a sleeping baby rat twitches, researchers record the extensive activity in the area of the rat’s brain that is sensitive to twitches of that limb. “We noticed there was a lot of brain activity during sleep movements but not when these animals were awake and moving,” Tiriac says.


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Rising Prevalence of Sleep Apnea in U.S. Threatens Public Health


Public health and safety are threatened by the increasing prevalence of obstructive sleep apnea, which now afflicts at least 25 million adults in the U.S., according to the National Healthy Sleep Awareness Project. Several new studies highlight the destructive nature of obstructive sleep apnea, a chronic disease that increases the risk of high blood pressure, heart disease, Type 2 diabetes, stroke and depression.


“Obstructive sleep apnea is destroying the health of millions of Americans, and the problem has only gotten worse over the last two decades,” said American Academy of Sleep Medicine President Dr. Timothy Morgenthaler, a national spokesperson for the Healthy Sleep Project. “The effective treatment of sleep apnea is one of the keys to success as our nation attempts to reduce health care spending and improve chronic disease management.”


Data previously published in the American Journal of Epidemiology show that the estimated prevalence rates of obstructive sleep apnea have increased substantially over the last two decades, most likely due to the obesity epidemic. It is now estimated that 26% of adults between the ages of 30 and 70 years have sleep apnea.


Findings from new studies emphasize the negative effects of sleep apnea on brain and heart health; however, these health risks can be reduced through the effective treatment of sleep apnea with continuous positive airway pressure therapy:


• A neuroimaging study in the September issue of the journal Sleep found that participants with severe, untreated sleep apnea had a significant reduction in white matter fiber integrity in multiple brain areas, which was accompanied by impairments to cognition, mood and daytime alertness. One year of CPAP therapy led to an almost complete reversal of this brain damage.

• A study published online ahead of print Sept. 21 in the journal NeuroImage found functional and anatomical changes in brainstem regions of people with sleep apnea.

• A study in the October issue of Anesthesiology shows that diagnosing sleep apnea and prescribing CPAP therapy prior to surgery significantly reduced postoperative cardiovascular complications — specifically cardiac arrest and shock — by more than half.

• A study published online ahead of print Sept. 19 in the Journal of Hypertension found a favorable reduction of blood pressure with CPAP treatment in patients with resistant hypertension and sleep apnea.

• A Brazilian population study published online ahead of print Sept. 23 found that nocturnal cardiac arrhythmias occurred in 92 percent of patients with severe sleep apnea, compared with 53 percent of people without sleep apnea. The prevalence of rhythm disturbance also increased with sleep apnea severity.


Source: National Healthy Sleep Awareness Project

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Surly Teens Get Surlier Thanks to Lack of Sleep


While American pediatricians warn that sleep deprivation can stack the deck against teenagers, a new study titled “Synchronizing education to adolescent biology: ‘let teens sleep, start school later” reveals that youth’s irritability and laziness may be attributable to lack of sleep.


Recently published in the journal of Learning, Media and Technology, this study exposes the negative consequences of sleep deprivation caused by early school bells, and shows that altering education times not only perks up teens’ mood, but also enhances learning and health.


It is no secret that human biology and education measure time in different ways; however, “our ability to function optimally [and learn], varies with biological time rather than conventional social times,” explains the team leading the research.

Things drastically change during adolescence, when “the conflict between social and biological time is greater than at any point in our lives,” continue the academics. Our sleep-wake cycle, or circadian rhythm, is the result of a complex balance between states of alertness and sleepiness regulated by a part of the brain called Suprachiasmatic Nucleus (SNC); in puberty, shifts in our body clocks push optimal sleep later into the evening, making it extremely difficult for most teenagers to fall asleep before 11:00 pm.


Early school starts in the morning result in chronically sleep-deprived and cranky teens as well as plummeting grades and health problems. There is a body of evidence showing the benefits of synchronising education times with teens’ body clocks; interestingly, while ‘studies of later start times have consistently reported benefits to adolescent sleep health and learning, there is no evidence showing early starts have a positive impact.


In spite of examples corroborating this theory—such as the case of the United States Air Force Academy where a later start policy boosted marks—educators still fail to grasp it’s not laziness that keeps teens in bed in the morning but their biological clocks.


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