Category: Insomnia

The quality of interactions among married couples is affected by wives' inability to fall asleep at night, but not by husbands' sleep problems, suggests new research being presented in Minneapolis, Minn., at SLEEP 2011, the 25th Anniversary Meeting of the Associated Professional Sleep Societies LLC (APSS).

Results show that, among wives, taking longer to fall asleep at night predicted their reports of more negative and less positive marital interactions the next day, and it also predicted their husband's reports of less positive marital interaction ratings the following day. In contrast, husbands' sleep did not affect their own or their wife's report of next day's marital interactions.

"We found that wives' sleep problems affect her own and her spouse's marital functioning the next day, and these effects were independent of depressive symptoms," said principal investigator Wendy M. Troxel, PhD, assistant professor of psychiatry at the University of Pittsburgh School of Medicine in Pittsburgh, Pa. "Specifically, wives who took longer to fall asleep the night before reported poorer marital functioning the next day, and so did their husbands."

The relationship between nightly sleep and next day's marital interactions was stronger than the association between daily marital interactions and subsequent sleep. Curiously, however, husbands' reports of higher levels of positive marital interactions predicted their own shorter sleep duration the next night.

The study involved 32 healthy, married couples with an average age of 32 years. Participants were free of clinically relevant sleep, psychiatric or medical disorders. Sleep latency, wakefulness after sleep onset, and total sleep time were measured by actigraphy for 10 nights. The quality of marital interactions was assessed daily over the 10-day assessment using electronic diaries to evaluate positive marital interactions such as feeling supported or valued by spouse, as well as negative marital interactions such as feeling criticized or ignored by spouse. Dyadic, time series analyses helped determine the direction of the relationship between sleep and marital interactions.

According to the authors, the findings show that sleep disorders such as insomnia can have a negative impact on marital relationships.

"These results highlight the importance of considering the interpersonal consequences of sleep and sleep loss," said Troxel.

The study was supported by the National Institutes of Health through the National Heart, Lung, and Blood Institute; and the Clinical & Translational Science Awards.

In previous studies, Troxel found that the stable presence of a husband or cohabiting partner predicted better sleep quality and continuity in women (SLEEP — July 2010); and women who were happy in their marriage reported fewer sleep disturbances (Behavioral Sleep Medicine — 2009).

The analysis of breathing sounds while awake may be a fast, simple and accurate screening tool for obstructive sleep apnea, suggests a research abstract being presented in Minneapolis, Minn., at SLEEP 2011, the 25th Anniversary Meeting of the Associated Professional Sleep Societies LLC (APSS).

Results show that several sound features of breathing were statistically significant between participants with obstructive sleep apnea and healthy controls. In an analysis that combined the two most significant sound features, the presence or absence of OSA was predicted with more than 84-percent accuracy. Sound analysis also allowed for the stratification of OSA severity.

According to the authors, people with OSA tend to have a narrower and more collapsible pharynx with more negative pharyngeal pressure, which creates greater resistance when breathing through the nose. Breathing sounds are directly related to pharyngeal pressure, making sound analysis a viable diagnostic option for OSA.

"Despite being able to breathe at the same high flow rate, the pharyngeal pressure in people with OSA during wakefulness is usually more negative than that in the non-OSA group," said principal investigator and lead author Zahra Moussavi, PhD, professor and Canada Research Chair on Biomedical Engineering at the University of Manitoba in Winnipeg, Canada.

Moussavi and co-investigator Aman Montazeri studied 35 patients with varying severity levels of OSA and 17 age-matched controls. The presence or absence of OSA was validated by full-night polysomnography.

The subjects were instructed to breathe through their nose at their normal breathing level for at least five breaths and then breathe at their maximum flow level for another five breaths. Then the process was repeated as they breathed through their mouth with a nose clip in place. The breathing sounds were picked up by a microphone placed over the neck, and the recordings were repeated in two body positions: sitting upright and lying on the back. Data were digitized and then analyzed using spectral and waveform fractal dimension techniques.

Moussavi added that detecting OSA through sound analysis could become an attractive alternative to the more costly and labor-intensive method of performing overnight polysomnography.

"If we can predict the likelihood of apnea and its severity with the same accuracy as in our pilot study, it will have a significant impact on health-care costs as it can reduce the need for full-night sleep assessment significantly," she said.

The study was supported by the National Sciences and Engineering Research Council of Canada and TRLabs Winnipeg, where Moussavi is an adjunct scientist.

According to the American Academy of Sleep Medicine, OSA is a sleep-related breathing disorder that involves a decrease or complete halt in airflow despite an ongoing effort to breathe. It occurs when the muscles relax during sleep, causing soft tissue in the back of the throat to collapse and block the upper airway. This leads to partial reductions (hypopneas) and complete pauses (apneas) in breathing that can produce abrupt reductions in blood oxygen saturation and reduce blood flow to the brain. Most people with OSA snore loudly and frequently, and they often experience excessive daytime sleepiness.

The treatment of choice for OSA is CPAP therapy, which provides a steady stream of air through a mask that is worn during sleep. This airflow keeps the airway open to prevent pauses in breathing and restore normal oxygen levels. Help for OSA is available at more than 2,200 AASM-accredited sleep disorders centers across the U.S.

New research presented on June 11, at the 20th Anniversary Meeting of the American Academy of Dental Sleep Medicine (AADSM) in Minneapolis, Minn., quantified the efficacy of mandibular advancement splints (MAS) using a self-administered, at-home device to monitor snoring and sleep-disordered breathing.

Clinical assessment of MAS efficacy in the treatment of snoring and obstructive sleep apnea (OSA) is based predominantly on subjective reports by the patient and partner, and less commonly, on the apnea hypopnea index (AHI), which is the average number of pauses in breathing that occur per hour of sleep. The current study used the Sonomat, a portable, unobtrusive device that has sensors contained within a mattress overlay. These sensors measure AHI by detecting and recording snoring, breathing and body movements.

Results show that MAS treatment reduced the average AHI from 10.3 events per hour to 3.8 events per hour. The respiratory event movement index (RMI), which records more types of events than AHI, was reduced from 15.9 events per hour to 7.6 events per hour.

There was also a decrease in the percentage of patients who snored from 38 percent without the MAS to 15 percent with the MAS. Snoring decreased overall, but 12 of the 42 subjects still snored for greater than 25 percent of the night, with several having substantial increases in snoring.

"The primary findings in our study were that MAS devices were effective in the treatment of OSA by reducing AHI in moderate and severe OSA patients," said principal investigator and lead author Joachim Ngiam, BDS. "Overall, significant reductions in snoring were found to occur with MAS therapy with greater changes seen in OSA patients."

The study involved data from 42 men and women over two consecutive nights. The subjects slept the first night without the MAS and the second night with the MAS advanced to 70 percent of maximum jaw protrusion.

The researchers also found what appeared to be a devolutionary effect with MAS treatment in attenuating or reversing the progression of a snorer's disease to OSA, as a substantial number of patients transitioned to lower AHI and snoring categories.

Despite favorable reductions in AHI with MAS treatment, snoring may persist and patients may question treatment success, indicating a need for quantification of therapy efficacy.

"Although significant reductions in AHI and snoring were observed, residual snoring may persist or even increase in some patients," said Ngiam. "A significant proportion of patients, 29 percent, still snored greater than 25 percent of total sleep time, with several having substantial increases despite MAS therapy."

People with primary insomnia may be able to find relief by wearing a cap that cools the brain during sleep, suggests a research abstract presented June 13, in Minneapolis, Minn., at Sleep 2011, the 25th Anniversary Meeting of the Associated Professional Sleep Societies LLC (APSS).

According to the authors, a reduction in metabolism in the brain's frontal cortex occurs while falling asleep and is associated with restorative sleep. However, insomnia is associated with increased metabolism in this same brain region. One way to reduce cerebral metabolic activity is to use frontal cerebral thermal transfer to cool the brain, a process known as "cerebral hypothermia."

Results show that there were linear effects of all-night thermal transfer intensities on sleep latency and sleep efficiency. The time that it took subjects with primary insomnia to fall asleep (13 minutes) and the percentage of time in bed that they slept (89 percent) during treatment at the maximal cooling intensity were similar to healthy controls (16 minutes and 89 percent).

"The most significant finding from this study is that we can have a beneficial impact on the sleep of insomnia patients via a safe, non-pharmaceutical mechanism that can be made widely available for home use by insomnia sufferers," said principal investigator and lead author Dr. Eric Nofzinger, professor and director of the Sleep Neuroimaging Research Program at the University of Pittsburgh School of Medicine. "The finding of a linear dose response effect of the treatment implies a direct beneficial impact on the neurobiology of insomnia that can improve the sleep of insomnia patients. We believe this has far-ranging implications for how insomnia can be managed in the future."

In this crossover study, Nofzinger and co-investigator Dr. Daniel Buysse screened 110 people, enrolling 12 people with primary insomnia and 12 healthy, age-and gender-matched controls. Participants with insomnia had an average age of about 45 years, and nine of the 12 subjects were women.

Participants received all-night frontal cerebral thermal transfer by wearing a soft plastic cap on their head. The cap contained tubes that were filled with circulating water. The effectiveness of varying thermal transfer intensities was investigated by implementing multiple conditions: no cooling cap, and cooling cap with either neutral, moderate or maximal cooling intensity.

According to Nofzinger, the simplicity and effectiveness of this natural treatment could be a long-awaited breakthrough for insomnia sufferers.

"The primary medical treatment for insomnia has long been the prescription of hypnotics, or sleeping pills, yet only about 25 percent of patients using these treatments are satisfied, citing concerns regarding side effects and the possibility of dependence on a pill to help them sleep at night," he said. "There exists a large gap between what patients with insomnia are looking for to help them and what is currently available. Patients have long sought a more natural, non-pharmaceutical means to help them with their sleep at night. The identification of a dose-dependent improvement by the device used in this study opens the door to a novel, safe and more natural way to achieve restorative sleep in insomnia care."

The American Academy of Sleep Medicine reports that chronic insomnia, or symptoms that last for at least a month, affects about 10 percent of adults. Most often insomnia is a "comorbid" disorder, occurring with another medical illness, mental disorder or sleep disorder, or associated with certain medications or substances. Fewer people suffering from insomnia are considered to have primary insomnia, which is defined as a difficulty falling asleep or maintaining sleep in the absence of coexisting conditions.

In a study published in 2006 in the Journal of Clinical Sleep Medicine, Nofzinger and Buysse reported that increased relative metabolism in several brain regions during non-REM sleep in patients with insomnia is associated with increased wakefulness after sleep onset. They speculated that these effects may result from increased activity in arousal systems during sleep or heightened cognitive activity related to processes such as conflict, anxiety, and fear.

— Large corporations could save millions of dollars in lost productivity by screening and treating high-risk employees for obstructive sleep apnea, suggests new research presented on June 13, in Minneapolis, Minn., at Sleep 2011, the 25th Anniversary Meeting of the Associated Professional Sleep Societies LLC (APSS).

Results show that a large corporation in Florida could save an estimated $136 million in lost productivity over 10 years by screening high-risk employees for OSA and offering treatment with continuous positive airway pressure (CPAP) therapy. The study found that 608 employees of the corporation were middle-aged, obese men who were at high risk for OSA.

According to the authors, untreated OSA results in job performance deficiencies such as excessive sleepiness, cognitive dysfunction, irritability and reduced vitality. Research shows that work performance can be decreased by 30 percent due to sleep fragmentation and repetitive hypoxia, which are characteristics of OSA.

"This cost-benefit analysis proposed OSA screening and treatment for high-level management professionals who had high salaries," said principal investigator Dr. Clelia Lima, a family nurse practitioner in the College of Nursing at the University of Central Florida in Orlando, Fla. "It was a pleasant surprise to find that the results showed substantial financial benefit for employees at practically any salary level."

Lima and co-investigator Dr. Elizabeth M. Rash, who is also a nurse practitioner, applied epidemiological data related to OSA screening, diagnosis and treatment to the specific demographics of the corporation. They based their calculations on statistics that 70 percent of high-risk individuals are diagnosed with OSA, and that 75 percent of patients with OSA are compliant with CPAP therapy. Therefore, they estimated that 319 of the 608 high-risk employees would have OSA and be compliant with treatment.

Then Lima and Rash made conservative statistical estimates, considering lost work productivity as the variable and using half of its predicted value. For each of the 319 treated employees, productivity was estimated at $150,000 per year. Recovering the 30 percent of productivity that was lost due to OSA would yield an annual gain of $14.4 million. Estimating the cost of diagnostic screening with polysomnography and treatment with CPAP therapy to be $7.2 million over 10 years, Lima and Rash determined that the corporation would have a 10-year net savings of $136 million.

Lima added that both companies and employees reap benefits when OSA is diagnosed and treated.

"Companies may become proactive in screening and treating their employees for OSA due to the predicted financial benefit," she said. "The importance goes beyond the improved cognitive function and savings of millions of dollars in work performance, since treating OSA adds other health benefits."

According to the American Academy of Sleep Medicine, it is estimated that about 80 to 90 percent of adults with OSA remain undiagnosed. OSA is a sleep-related breathing disorder that involves a decrease or complete halt in airflow despite an ongoing effort to breathe. It occurs when the muscles relax during sleep, causing soft tissue in the back of the throat to collapse and block the upper airway. This leads to partial reductions (hypopneas) and complete pauses (apneas) in breathing that can produce abrupt reductions in blood oxygen saturation and reduce blood flow to the brain. Most people with OSA snore loudly and frequently, and they often experience excessive daytime sleepiness.

The treatment of choice for OSA is CPAP therapy, which provides a steady stream of air through a mask that is worn during sleep. This airflow keeps the airway open to prevent pauses in breathing and restore normal oxygen levels. Help for OSA is available at more than 2,200 AASM-accredited sleep disorders centers across the U.S.

 Daytime sleepiness may affect inhibitory control in the brain when viewing tantalizing, high-calorie foods, suggests new research presented on June 13, in Minneapolis, Minn., at Sleep 2011, the 25th Anniversary Meeting of the Associated Professional Sleep Societies LLC (APSS).

Results show that greater daytime sleepiness was associated with decreased activation in the prefrontal cortex during visual presentations of enticing, high-calorie food images. The prefrontal cortex is a brain region that plays an important role in inhibitory processing.

"Self-reported daytime sleepiness among healthy, normally rested individuals correlated with reduced responsiveness of inhibitory brain regions when confronted with images of highly appetizing foods," said principal investigator William Killgore, PhD, assistant professor of psychology at Harvard Medical School and McLean Hospital in Belmont, Mass. "It suggests that even normal fluctuations in sleepiness may be capable of altering brain responses that are important for regulating dietary intake, potentially affecting the types of choices that individuals make when selecting whether and what to eat."

The research team of Killgore, lead author Melissa Weiner, and Zachary Schwab studied 12 healthy men and women between the ages of 19 and 45 years. The participants underwent functional magnetic resonance imaging (fMRI) while viewing pictures of high-calorie foods, low-calorie foods, and control images of plants and rocks. Subjective, self-reported daytime sleepiness was measured with the Epworth Sleepiness Scale, which evaluates how likely an individual is to doze off or fall asleep during certain situations such as while sitting and reading or watching TV.

According to the authors, prior evidence suggests that healthy adults activate inhibitory regions of the prefrontal cortex in response to high-calorie food images. However, insufficient sleep is often associated with reduced metabolic activity within these same prefrontal regions.

Killgore noted that the rapidly rising rate of obesity makes it important to understand the relationship between sleep-related factors, brain responses to food, and eating behavior.

"Given the chronic level of sleep restriction in our society, such relationships could have epidemiologic implications regarding the current increase in obesity in westernized countries," he said.

In a previous study published in Neuroreport in 2010, Killgore also found sex differences in cerebral responses to the caloric content of food images. Results of that study indicate that when viewing high-calorie food images, women showed significantly greater activation than men in brain regions that are involved in behavioral control and self-referential cognition.

— A Major League Baseball player's natural sleep preference might affect his batting average in day and night games, according to a research abstract presented on June 13, in Minneapolis, Minn., at Sleep 2011, the 25th Anniversary Meeting of the Associated Professional Sleep Societies LLC (APSS).

Results indicate that players who were "morning types" had a higher batting average (.267) than players who were "evening types" (.259) in early games that started before 2 p.m. However, evening types had a higher batting average (.261) than morning types (.252) in mid-day games that started between 2 p.m. and 7:59 p.m. This advantage for evening types persisted and was strongest in late games that began at 8 p.m. or later, when evening types had a .306 batting average and morning types maintained a .252 average.

"Our data, though not statistically significant due to low subject numbers, clearly shows a trend toward morning-type batters hitting progressively worse as the day becomes later, and the evening-types showing the opposite trend," said principal investigator and lead author Dr. W. Christopher Winter, medical director of the Martha Jefferson Hospital Sleep Medicine Center in Charlottesville, Va.

The study involved 16 players from seven MLB teams: the Houston Astros, Los Angeles Angels, Los Angeles Dodgers, Pittsburgh Pirates, St. Louis Cardinals, San Francisco Giants and Toronto Blue Jays. Sleep preference was determined using a modified version of the Morningness-Eveningness Questionnaire (MEQ). It identifies a person's tendency to be either a morning type who prefers to go to bed and wake up early, or an evening type who prefers to stay up late at night and wake up late in the day. Nine participants were found to be evening types, and seven were morning types. Both groups had a mean age of 29 years.

The study used the players' statistics from the 2009 and 2010 seasons, which allowed for the analysis of 2,149 innings from early games, 4,550 innings from mid-day games and 750 innings from late games. Game start times were adjusted for travel using the principle that for every time zone crossed, it takes 24 hours to adjust.

"These results are important as they create an entirely new way to look at athletic talent," said Winter. "Currently, selecting a player for a game situation usually involves factors such as handedness, rest, and possibly previous success against a certain team. Now, the time of day in which the game is occurring and a player's chronotype might be a wise factor to take into account."

Winter noted that he plans to analyze more players and precise batting times to better understand this effect.

Last year at SLEEP 2010, Winter presented the results of a similar study, reporting that pitchers who were morning types performed statistically better overall than those who were evening types. However, in games that started at 7 p.m. or later, pitchers who were evening types performed slightly better than morning types.

Winter added that many MLB teams that have participated in his studies are showing an increasing level of interest in his research after seeing his latest results. With the help of co-investigator Ben Potenziano of the San Francisco Giants, and generous assistance from Ron Porterfield of the Tampa Bay Rays, teams have supplied him with more than 300 player data surveys for analysis.

"Clearly, the teams think it is important," said Winter.

NewsPsychology (June 10, 2011) — Suffering from parental abuse as a child increases a person’s chances of having poor sleep quality in old age, according to a research article in the current issue of the Journals of Gerontology Series B: Psychological and Social Sciences (Volume 66B, Number 3).

An analysis of data from 877 adults age 60 years and above found that early parental emotional abuse was associated with a higher number of sleep complaints in old age. It was specifically emotional abuse — rather than physical abuse or emotional neglect — that was tied to trouble in getting a good night’s sleep.

“A negative early attachment continues to exert an influence on our well being decades later through an accumulation of stressful interpersonal experiences across our lives,” said Cecilia Y. M. Poon, MA, the study’s lead author. “The impact of abuse stays in the system. Emotional trauma may limit a person’s ability to fend for themselves emotionally and successfully navigate the social world”

The data was taken from the National Survey of Midlife Development in the United States. In 1995, approximately 3,500 adults responded to questions about their childhood. A decade later, they were asked follow-up questions about sleep, relationships, and emotional distress. Poon’s study looked at the answers from those age 60 and above.

During the second round of interviews, the participants were asked how often within the previous 30 day they had trouble falling asleep, woke up during the night and had difficulty going back to sleep, woke up too early in the morning and were unable to get back to sleep, and felt unrested during the day no matter how many hours of sleep they had. Emotional abuse was assessed by asking participants how often their mother and father insulted or swore at them, sulked or refused to talk to them, stomped out of the room, did or said something to spite them, threatened to hit them, or smashed or knocked something in anger.

The same survey found that emotional abuse during childhood also was associated with poorer relationships in adulthood. Poon speculated that this lack of support, associated with stress, likely influences sleep quality.

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The above story is reprinted (with editorial adaptations by newsPsychology staff) from materials provided by The Gerontological Society of America.

Journal Reference:

1. C. Y. M. Poon, B. G. Knight. Impact of Childhood Parental Abuse and Neglect on Sleep Problems in Old Age. The Journals of Gerontology Series B: Psychological Sciences and Social Sciences, 2011; 66B (3): 307 DOI: 10.1093/geronb/gbr003

Disclaimer: This article is not intended to provide medical advice, diagnosis or treatment. Views expressed here do not necessarily reflect those of NewsPsychology or its staff.

NewsPsychology (June 8, 2011) — In recent years, much sleep research has focused on memory, but now results of a new study by University of Massachusetts Amherst psychologist Rebecca Spencer and colleagues suggest another key effect of sleep is facilitating and enhancing complex cognitive skills such as decision-making.

In one of the first studies of its kind, Spencer and postdoctoral fellow Edward Pace-Schott investigated the effects of sleep on affect-guided decision-making, that is decisions on meaningful topics where subjects care about the outcome, in a group of 54 young adults. They were taught to play a card game for rewards of play money in which wins and losses for various card decks mimic casino gambling.

Subjects who had a normal night’s sleep as part of the study drew from decks that gave them the greatest winnings four times more often than those who spent the 12-hour break awake, and they better understood the underlying rules of the game. Psychologists believe rule discovery is an often hidden yet key factor that is crucial to making sound decisions.

“This provides support for what Mom and Dad have always advised,” says Spencer. “There is something to be gained from taking a night to sleep on it when you’re facing an important decision. We found that the fact that you slept makes your decisions better.”

This role of sleep in everyday life is accepted as common wisdom, but it hasn’t been well characterized by science until now, she adds. She and her colleagues believe this sleep benefit in making decisions may be due to changes in underlying emotional or cognitive processes. “Our guess is that this enhanced effect on decision-making is something that depends on rapid-eye-movement or REM sleep, which is the creative period of our sleep cycle,” the psychologist notes. Results are in the current early online issue of the Journal of Sleep Research.

The UMass Amherst study used the Iowa Gambling Task, a gambling card game that assesses frontal lobe function, where more emotional decisions originate. Spencer explains, “It means that you care about the wins and losses. You care about winning.”

To begin, the researchers gave two groups of 18- to 23-year-old college undergraduates a brief morning or afternoon preview of the gambling task, so brief that it was not possible for them to learn its underlying rule. Subjects were then asked to come back in 12 hours. The 28 subjects who got the preview in the afternoon went home to a normal evening and their usual night of sleep while the 26 who received the game preview in the morning came back after a day of normal activities with no naps.

On the second visit, subjects played the full gambling task for long enough to learn that drawing cards from four decks of cards yielded different rewards of play money: Drawing from two advantageous decks yielded low rewards, occasional low losses and a net gain over many draws, while drawing from disadvantageous decks yielded high rewards, occasional high losses and a net loss over many draws. The object was to avoid losing and collect as much play money as possible.

Subjects who got to sleep between the game’s brief introduction and the longer play session showed both superior behavioral outcome, that is, more advantageous draws, and superior rule understanding when asked to explain them at the end, than those who did not sleep between sessions.

To assure that time of day didn’t explain the different performance between sleep and wake groups, the researchers added two smaller groups of 17 and 21 subjects to perform both the preview and the full task either in the morning or the evening. All subjects said they had normal sleep patterns (for college students) and the groups didn’t differ on overall game skills at the start. Males and females do not differ in game-playing skills, the authors point out, but there were equal numbers in each group.

This work was supported by the National Institute on Aging at the National Institutes of Health. Spencer and her UMass Amherst colleagues have begun new studies to more specifically explore the relationship between REM sleep duration and success on decision-making tasks. They are also launching studies of the relationship between sleep and decision-making in older adults.

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Story Source:

The above story is reprinted (with editorial adaptations by newsPsychology staff) from materials provided by University of Massachusetts Amherst.

Journal Reference:

1. Edward F. Pace-Schott, Genevieve Nave, Alexandra Morgan, Rebecca M. C. Spencer. Sleep-dependent modulation of affectively guided decision-making. Journal of Sleep Research, 2011; DOI: 10.1111/j.1365-2869.2011.00921.x

Disclaimer: This article is not intended to provide medical advice, diagnosis or treatment. Views expressed here do not necessarily reflect those of NewsPsychology or its staff.

From high-school students to surgeons, anyone who has pulled an all-nighter knows there is a price to be paid the next day: trouble focusing, a fuzzy memory and other cognitive impairments. Now, researchers at Penn have found the part of the brain and the neurochemical basis for sleep deprivation's effects on memory.

Ted Abel, a professor of biology in Penn's School of Arts and Sciences and director of the University's interdisciplinary Biological Basis of Behavior program, led the research team. His partners included Cédrick Florian, a postdoctoral fellow in biology, and Christopher Vecsey, a neuroscience graduate student, as well as researchers from the Massachusetts Institute of Technology and Tufts University.

Their research was published in The Journal of Neuroscience.

Abel's group aimed to better understand the role of the nucleoside adenosine in the hippocampus, the part of the brain associated with memory function.

"For a long time, researchers have known that sleep deprivation results in increased levels of adenosine in the brain, and has this effect from fruit flies to mice to humans." Abel said. "There is accumulating evidence that this adenosine is really the source of a number of the deficits and impact of sleep deprivation, including memory loss and attention deficits. One thing that underscores that evidence is that caffeine is a drug that blocks the effects of adenosine, so we sometimes refer to this as 'the Starbucks experiment.'"

Abel's research actually involved two parallel experiments on sleep-deprived mice, designed to test adenosine's involvement in memory impairment in different ways.

One experiment involved genetically engineered mice. These mice were missing a gene involved in the production of glial transmitters, chemicals signals that originate from glia, the brain cells that support the function of neurons. Without these gliatransmitters, the engineered mice could not produce the adenosine the researchers believed might cause the cognitive effects associated sleep deprivation.

The other experiment involved a pharmacological approach. The researchers grafted a pump into the brains of mice that hadn't been genetically engineered; the pump delivered a drug that blocked a particular adenosine receptor in the hippocampus. If the receptor was indeed involved in memory impairment, sleep-deprived mice would behave as if the additional adenosine in their brains was not there.

To see whether these mice showed the effects of sleep deprivation, the researchers used an object recognition test. On the first day, mice were placed in a box with two objects and were allowed to explore them while being videotaped. That night, the researchers woke some of the mice halfway through their normal 12-hour sleep schedule.

On the second day, the mice were placed back in the box, where one of the two objects had been moved, and were once again videotaped as they explored to see how they reacted to the change.

"Mice would normally explore that moved object more than other objects, but, with sleep deprivation, they don't," Abel said. "They literally don't know where things are around them."

Both sets of treated mice explored the moved object as if they had received a full night's sleep.

"These mice don't realize they're sleep-deprived," Abel said.

Abel and his colleagues also examined the hippocampi of the mice, using electrical current to measure their synaptic plasticity, or how strong and resilient their memory-forming synapses were. The pharmacologically and genetically protected mice showed greater synaptic plasticity after being sleep deprived than the untreated group.

Combined, the two experiments cover both halves of the chemical pathway involved in sleep deprivation. The genetic engineering experiment shows where the adenosine comes from: glia's release of adenosine triphosphate, or ATP, the chemical by which cells transfer energy to one another. And the pharmacological experiment shows where the adenosine goes: the A1 receptor in the hippocampus.

The knowledge that interrupting the pathway at either end results in mice that show no memory impairments is a major step forward in understanding how to manage those impairments in humans.

"To be able to reverse a particular aspect of sleep-deprivation, such as its effect on memory storage, we really want to understand the molecular pathways and targets," Abel said. "Here, we've identified the molecule, the cellular circuit and the brain region by which sleep deprivation affects memory storage."

Such treatments would be especially enticing, given how sensitive the brain is to sleep deprivation's effects.

"Our sleep deprivation experiments are the equivalent of losing half of a night sleep for a single night," Abel said. "Most of us would think that's pretty minor, but it shows just how critical the need for sleep is for things like cognition."

In addition to Abel, Florian and Vescey, the research was conducted by Michael M. Halassa of the Department of Psychiatry at Massachusetts General Hospital and the Department of Brain and Cognitive Science at MIT, as well as Philip G. Haydon, of the Department of Neuroscience at the Tufts University School of Medicine.

The research was supported by the National Institutes of Health.

Journal Reference:

1. C. Florian, C. G. Vecsey, M. M. Halassa, P. G. Haydon, T. Abel. Astrocyte-Derived Adenosine and A1 Receptor Activity Contribute to Sleep Loss-Induced Deficits in Hippocampal Synaptic Plasticity and Memory in Mice. Journal of Neuroscience, 2011; 31 (19): 6956 DOI: 10.1523/JNEUROSCI.5761-10.2011