1. Sleep may influence an eyewitness’s ability to identify guilty person

    September 18, 2017 by Ashley

    From the Michigan State University press release:

    Sleep may influence an eyewitness’s ability to correctly pick a guilty person out of a police lineup, indicates a study by Michigan State University researchers.

    Published in PLOS ONE, the research found that eyewitnesses to a crime who sleep before being given a lineup are much less likely to pick an innocent person out of a lineup — at least when the perpetrator is not in the lineup.

    Some 70 percent of wrongful convictions in the United States are related to false eyewitness accounts. This study is the first scientific investigation into how sleep affects eyewitness memory of a crime, said lead author Michelle Stepan, a doctoral student in psychology.

    “It’s concerning that more people aren’t making the correct decision during lineups; this suggests our memories are not super accurate and that’s a problem when you’re dealing with the consequences of the criminal justice system,” Stepan said. “Putting someone in jail is a big decision based on somebody’s memory of a crime.”

    Stepan and Kimberly Fenn, associate professor of psychology and director of MSU’s Sleep and Learning Lab, conducted an experiment in which about 200 participants watched a video of a crime (a man planting a bomb on a rooftop) and then, 12 hours later, viewed one of two computer lineups of six similar-looking people. One lineup included the perpetrator; the other lineup did not.

    Some participants watched the crime video in the morning and viewed a lineup that night, with no sleep in between. Others watched the crime video at night and viewed a lineup the next morning, after sleeping.

    When the perpetrator was not in the lineup, participants who had slept identified an innocent person 42 percent of the time — compared to 66 percent for participants who had not slept.

    “This is the most interesting finding of the study — that individuals are less likely to choose an innocent suspect after a period of sleep when the perpetrator is absent from the lineup,” Fenn said. This is relevant, she added, because false convictions too often stem from an incorrect eyewitness identification of a suspect who did not commit the crime.

    When the perpetrator was in the lineup, there was essentially no difference between the sleep and no-sleep groups’ ability to choose the guilty man. Both groups correctly identified the perpetrator about 50 percent of the time.

    “In other words,” Fenn said, “sleep may not help you get the right guy, but it may help you keep an innocent individual out of jail.”

    The results could reflect both changes in memory strength and decision-making strategies after sleep.

    The researchers believe participants who slept were more likely to use an “absolute strategy,” in which they compare each person in the lineup to their memory of the suspect, while participants who didn’t sleep were more likely to use a “relative strategy,” in which they compare the people in the lineup to each other to determine who most resembles the perpetrator relative to the others.

    Using a relative strategy is believed to increase false identifications relative to an absolute strategy in perpetrator-absent lineups, Stepan said.

    “These findings tell us that sleep likely impacts memory processes but that it might also impact how people search through a lineup, and those search strategies might be a critical factor when the perpetrator is not in the lineup,” she said.

    Fenn noted that the key findings of the study have since been replicated.

    The MSU team is conducting research that further explores how sleep may directly or indirectly affect eyewitness memory.


  2. Study finds active ingredient in sugarcane may help with stress-related insomnia

    by Ashley

    From the University of Tsukuba press release:

    Everyone empirically knows that stressful events certainly affect sound sleep. Scientists in the Japanese sleep institute found that the active component rich in sugarcane and other natural products may ameliorate stress and help having sound sleep.

    In today’s world ever-changing environment, demanding job works and socio-economic factors enforces sleep deprivation in human population. Sleep deprivation induces tremendous amount of stress, and stress itself is one of the major factors responsible for sleep loss or difficulty in falling into sleep. Currently available sleeping pills does not address stress component and often have severe side effects. Sleep loss is also associated with certain other diseases including obesity, cardiovascular diseases, depression, anxiety, mania deficits etc.

    The research group led by Mahesh K. Kaushik and Yoshihiro Urade of the International Institute for Integrative Sleep Medicine (WPI-IIIS), University of Tsukuba, found that octacosanol reduces stress and restores stress-affected sleep back to normal.

    Octacosanol is abundantly present in various everyday foods such as sugarcane (thin whitish layer on surface), rice bran, wheat germ oil, bee wax etc. The crude extract is policosanol, where octacosanol is the major constituent. Policosanol and octacosanol have already been used in humans for various other medical conditions.

    In the current study, authors made an advancement and investigated the effect of octacosanol on sleep regulation in mildly stressed mice by oral administration. Octacosanol reduced corticosterone level in blood plasma, which is a stress marker. The octacosanol-administered mice also showed normal sleep, which was previously disturbed due to stress. They therefore claim that the octacosanol mitigates stress in mice and restores stress-affected sleep to normal in mice. The sleep induced by octacosanol was similar to natural sleep and physiological in nature. However, authors also claimed that octacosanol does not affect sleep in normal animals. These results clearly demonstrated that octacosanol is an active compound that has potential to reduce stress and to increase sleep, and it could potentially be useful for the therapy of insomnia caused by stress. Octacosanol can be considered safe for human use as a therapy, because it is a food-based compound and believed to show no side effects.

    Octacosanol/policosanol supplements are used by humans for functions such as lipid metabolism, cholesterol lowering or to provide strength. However, well-planned clinical studies need to be carried out to confirm its effect on humans for its stress-mitigation and sleep-inducing potentials. “Future studies include the identification of target brain area of octacosanol, its BBB permeability, and the mechanism via which octacosanol lowers stress,” Kaushik says.


  3. Study suggests ADHD may be linked to sleep problems

    September 16, 2017 by Ashley

    From the European College of Neuropsychopharmacology press release:

    Around 75% of children and adults with Attention Deficit Hyperactivity Disorder (ADHD) also have sleep problems, but until now these have been thought to be separate issues. Now a in a pulling together of the latest research, Scientists are proposing of a new theory which says that much of ADHD may in fact be a problem associated with lack of regular circadian sleep.

    Presenting the proposal at the ECNP Conference in Paris, Professor Sandra Kooij (Associate Professor of Psychiatry at VU University Medical Centre, Amsterdam and founder and chair of the European Network Adult ADHD) said:

    “There is extensive research showing that people with ADHD also tend to exhibit sleep problems. What we are doing here is taking this association to the next logical step: pulling all the work together leads us to say that, based on existing evidence, it looks very much like ADHD and circadian problems are intertwined in the majority of patients.

    We believe this because the day and night rhythm is disturbed, the timing of several physical processes is disturbed, not only of sleep, but also of temperature, movement patterns, timing of meals, and so on.

    If you review the evidence, it looks more and more like ADHD and sleeplessness are 2 sides of the same physiological and mental coin.”

    Professor Kooij laid out the links which have led to the synthesis:

    • In 75% of ADHD patients, the physiological sleep phase — where people show the physiological signs associated with sleep, such as changes in the level of the sleep hormone melatonin, and changes in sleep-related movement — is delayed by 1.5 hours.
    • Core body temperature changes associated with sleep are also delayed (reflecting melatonin changes)
    • Many sleep-related disorders are associated with ADHD, including restless-leg syndrome, sleep apnea, and the circadian rhythm disturbance, the delayed sleep phase syndrome
    • ADHD people often show greater alertness in the evening, which is the opposite of what is found in the general population
    • Many sufferers benefit from taking melatonin in the evening or bright light therapy in the morning, which can help reset the circadian rhythm
    • Recent work has shown that around 70% of adult ADHD sufferers show an oversensitivity of the eyes to light, leading many to wear sunglasses for long periods during the day — which may reinforce the problems associated with a ‘circadian shift’.
    • Chronic late sleep leads to a chronic sleep debt, associated with obesity, diabetes, cardiovascular disease and cancer. This cascade of negative health consequences may in part be preventable by resetting the sleep rhythm.

    Professor Kooij continued:

    “We are working to confirm this physical-mental relationship by finding biomarkers, such as Vitamin D levels, blood glucose, cortisol levels, 24 hour blood pressure, heart rate variability, and so on. If the connection is confirmed, it raises the intriguing question: does ADHD cause sleeplessness, or does sleeplessness cause ADHD? If the latter, then we may be able to treat some ADHD by non-pharmacological methods, such as changing light or sleep patterns, and prevent the negative impact of chronic sleep loss on health.”

    “We don’t say that all ADHD problems are associated with these circadian patterns, but it looks increasingly likely that this is an important element.”

    Commenting, Professor Andreas Reif (University Hospital, Frankfurt, and leader of the EU CoCA project on ADHD ), who was not involved in the research, said “A disturbance of the circadian system may indeed be a core mechanism in ADHD, which could also link ADHD to other mental illnesses such as depression or bipolar disorder. But also beyond these pathophysiological considerations, sleep problems and abnormalities of circadian rhythms are a huge problem for many patients, heavily impacting on their social life” He continued “More research into the interconnections between ADHD and the “inner clock” is thus very relevant to improve patients’ lives and to shed light on the disease mechanism of ADHD.”

    Note: Attention deficit hyperactivity disorder (ADHD) is a group of behavioural symptoms with a neurobiological background, that include inattentiveness, hyperactivity, mood swings and impulsiveness. ADHD is highly heritable, and several differences in brain volume and function have been shown compared to controls. Symptoms of ADHD tend to be noticed at an early age and may become more noticeable when a child’s circumstances change, such as when they start school. Most cases are diagnosed when children are 6 to 12 years old, but ADHD is also increasingly recognised in adults and older people, as ADHD can persist during the lifespan. People with ADHD often have additional problems, such as sleep, mood- and anxiety disorders. Between 2 and 5 % of children, adults and older people suffer from ADHD.


  4. Children’s sleep quality linked to mothers’ insomnia

    September 15, 2017 by Ashley

    From the University of Warwick press release:

    Children sleep more poorly if their mothers suffer from insomnia symptoms — potentially affecting their mental wellbeing and development — according to new research by the University of Warwick and the University of Basel.

    Led by Dr Sakari Lemola from Warwick’s Department of Psychology and Natalie Urfer-Maurer from the University of Basel, the study reported in Sleep Medicine shows that children of mothers with insomnia symptoms fall asleep later, get less sleep, and spend less time in deep sleep.

    Analysing data from nearly 200 healthy 7-12 year old children and their parents, the researchers studied the relationship between the parents’ insomnia symptoms and their children’s sleep quality.

    Sleep was assessed in the children during one night with in-home electroencephalography (EEG) — a method used to record electrical activity in the brain and makes it possible to identify different sleep stages — whilst parents reported their own insomnia symptoms and their children’s sleep problems.

    The researchers found that children whose mothers have insomnia symptoms fall asleep later, get less sleep, and spend less time in deep sleep, as measured by EEG.

    However, there was no association between the fathers’ sleep problems and children’s sleep as measured by EEG.

    The study suggests that the reason why children’s sleep is more closely related to mothers’ sleep than to fathers’ sleep is that, on average, mothers still spend more time with their children than fathers — and therefore, a stronger mutual influence is likely.

    When parents reported their children’s sleep, both mothers and fathers with sleep problems more often reported that their children had difficulties getting into bed and did not sleep enough.

    Sleep plays an essential role for adults’ and children’s well-being. Short sleep and poor sleep quality can affect mental health, learning, memory, and school achievement in children. In adulthood around 30% of people suffer from disturbed sleep. The most common sleep disorder in adulthood is insomnia, which is defined by symptoms such as difficulty falling or staying asleep at night.

    “These findings are important because sleep in childhood is essential for wellbeing and development,” commented Dr Sakari Lemola. “The findings show that children’s sleep has to be considered in the family context. In particular, the mother’s sleep appears to be important for how well school-aged children sleep.”

    Several mechanisms could account for the relationship between parents’ and children’s sleep. First, children may learn sleep habits from their parents. Second, poor family functioning could affect both parents’ and children’s sleep. For instance, family fights in the evening before bedtime may prevent the whole family from a good night’s sleep.

    Third, it is possible that parents suffering from poor sleep show “selective attention” for their own as well as their children’s sleep problems, leading to increased monitoring of sleep. It is possible that increased monitoring and attempts to control sleep may negatively affect sleep quality. Finally, children may also share genes with their parents that predispose them to poor sleep.

    The research, ‘The association of mothers’ and fathers’ insomnia symptoms with school-aged children’s sleep assessed by parent report and in-home sleep-electroencephalography’, is published in Sleep Medicine.


  5. Chronic lack of sleep increases risk-seeking

    September 12, 2017 by Ashley

    From the University of Zürich press release:

    Young adults have a natural sleep requirement of about 9 hours a day on average, older adults 7.5 hours. Many people in western societies, however, get considerably less sleep. According to studies, about one-third of the persons surveyed in several industrial countries reported too little sleep. If a young adult sleeps less than 8 hours a night, increased attention deficits occur, which can lead to considerable negative consequences. In sleep clinics there is an increasing number of healthy people who are suffering from the negative consequences of insufficient sleep.

    Not enough sleep leads to riskier decision-making

    Researchers at the University of Zurich and the University Hospital Zurich have now identified a further critical consequence of a chronic lack of sleep: increased risk-seeking. The sleep and neuroeconomics scientists studied the risk behavior of 14 healthy male students aged from 18 to 28 years. If the students slept only 5 hours a night for a week, they displayed clearly riskier behavior in comparison with a normal sleep duration of about 8 hours. Twice a day, they had to choose between obtaining a specified amount of money paid out with a given probability or playing it safe with a lower amount of money paid out for sure. The riskier the decision, the higher the possible prize — but also the risk of getting nothing.

    Riskier behavior remains unnoticed

    While a single sleepless night had no effect on risk-seeking, 11 of 14 of the subjects behaved significantly and increasingly riskier as the week of a reduced sleep duration went on. An additional finding is particularly alarming: The students assess their risk-taking behavior to be the same as under regular sleep conditions. “We therefore do not notice ourselves that we are acting riskier when suffering from a lack of sleep,” emphasizes Christian Baumann, professor of neurology and the head of the Clinical Research Priority Programs (CRPP) “Sleep and Health” at UZH. According to the authors of the study, we should therefore all strive for a sufficient sleep duration — especially political and economic leaders who make wide-reaching decisions daily. “The good news is,” Baumann says, “that, in the high-powered world of managers, getting enough sleep is increasingly being seen as desirable.”

    Lack of recovery in important regions of the brain

    For the first time, the researchers have proven that a low depth of sleep in the right prefrontal cortex is directly connected with higher risk-seeking behavior. This part of the cerebral cortex has already been associated with risk-taking behavior in earlier studies. “We assume that behavioral changes occur for anatomical-functional reasons to some extent as a result of the right prefrontal cortex not being able to recover properly due to a chronic lack of sleep,” Baumann concludes.


  6. Less REM sleep tied to greater risk of dementia

    September 9, 2017 by Ashley

    From the American Academy of Neurology (AAN) press release:

    People who get less rapid eye movement (REM) sleep may have a greater risk of developing dementia, according to a new study published in the August 23, 2017, online issue of Neurology®, the medical journal of the American Academy of Neurology. REM sleep is the sleep stage when dreaming occurs.

    There are five stages of sleep. Stage one is light sleep. Stage two is when the body begins to prepare for deeper sleep, including stages three and four. Stage five is REM sleep. During this dream stage, the eyes move rapidly and there is increased brain activity as well as higher body temperature, quicker pulse and faster breathing. The first REM stage occurs about an hour to an hour-and-a-half into sleep and then recurs multiple times throughout the night as the cycles repeat.

    “Sleep disturbances are common in dementia but little is known about the various stages of sleep and whether they play a role in dementia risk,” said study author Matthew P. Pase, PhD, of Swinburne University of Technology in Australia. “We set out to discover which stages of sleep may be linked to dementia and while we did not find a link with deep sleep, we did with REM sleep.”

    For the study, researchers looked at 321 people with an average age of 67 from Massachusetts who participated in The Framingham Heart Study. During that study, sleep cycles were measured for each participant. Researchers collected the sleep data and then followed participants for an average of 12 years. During that time, 32 people were diagnosed with some form of dementia and of those, 24 were determined to have Alzheimer’s disease.

    The people who developed dementia spent an average of 17 percent of their sleep time in REM sleep, compared to 20 percent for those who did not develop dementia. After adjusting for age and sex, researchers found links between both a lower percentage of REM sleep and a longer time to get to the REM sleep stage and a greater risk of dementia. In fact, for every percent reduction in REM sleep there was a 9 percent increase in the risk of dementia. The results were similar after researchers adjusted for other factors that could affect dementia risk or sleep, such as heart disease factors, depression symptoms and medication use.

    Other stages of sleep were not associated with an increased dementia risk.

    “Our findings point to REM sleep as a predictor of dementia,” said Pase. “The next step will be to determine why lower REM sleep predicts a greater risk of dementia. By clarifying the role of sleep in the onset of dementia, the hope is to eventually identify possible ways to intervene so that dementia can be delayed or even prevented.”

    Limitations of the study include a small sample size. Studies on larger groups of people need to be done to confirm findings. There was also no data available on shift work among study participants, which can cause unusual sleep patterns and possibly lead to sleep disorders.


  7. Blue light emitted by screens damages our sleep

    September 5, 2017 by Ashley

    From the University of Haifa press release:

    The short-wavelength blue light, emitted by the screens we watch, damages the duration, and even more so, the quality of our sleep. This is the conclusion of a new study undertaken by the University of Haifa and Assuta Sleep Clinic. The study also found that watching screens that emit red light does not cause damage, and sleep after exposure to it was similar to normal sleep. “The light emitted by most screens — computers, smartphones, and tablets — is blue light that damages the body’s cycles and our sleep,” explains Prof. Abraham Haim from the University of Haifa, one of the authors of the study. “The solution must be the use of the existing filters that prevent the emission of this light.”

    Previous studies have already shown that watching screens before going to sleep damages our sleep. It has also been found that exposure to blue light with wave lengths of 450-500 nanometers suppresses the production of melatonin, a hormone secreted at night that is connected with normal body cycles and sleep. The new study, published in the journal Chronobiology International, was undertaken by researchers Prof. Abraham Haim, head of the Israeli center for interdisciplinary research in chronobiology at the University of Haifa; doctorate student Amit Shai Green of the Center for Interdisciplinary Chronobiological Research at the University of Haifa and the Sleep and Fatigue Center at Assuta Medical Center; Dr. Merav Cohen-Zion of the School of Behavioral Sciences at the Academic College of Tel Aviv-Yafo; and Prof. Yaron Dagan of the Research Institute for Applied Chronobiology at Tel Hai Academic College. The researchers sought to examine whether there is any difference in sleep patterns following exposure to blue screen light as compared to red light prior to sleep, and furthermore, to find which is more disruptive: wavelength or intensity?

    The study participants were 19 healthy subjects aged 20-29 who were not aware of the purpose of the study. In the first part of the trial, the participants wore an actigraph for one week (an actigraph is a device that provides an objective measurement of the time when an individual falls asleep and wakes up). They also completed a sleep diary and a questionnaire about their sleeping habits and quality of sleep. In the second part of the trial, which took place at Assuta’s Sleep Laboratory, the participants were exposed to computer screens from 9 p.m. to 11 p.m. — the hours when the pineal gland begins to produce and excrete melatonin. The participants were exposed to four types of light: high-intensity blue light, low-intensity blue light, high-intensity red light, and low-intensity red light. Following exposure to light, they were connected to instruments that measure brain waves and can determine the stages of sleep a person undergoes during the course of the night, including awakenings not noticed by the participants themselves. In the morning, the participants completed various questionnaires relating to their feelings.

    On average, exposure to blue light reduced the duration of sleep by approximately 16 minutes. In addition, exposure to blue light significantly reduced the production of melatonin, whereas exposure to red light showed a very similar level of melatonin production to the normal situation. The researchers explain that the impaired production of melatonin reflects substantial disruption of the natural mechanisms and the body’s biological clock. Thus, for example, it was found that exposure to blue light prevents the body from activating the natural mechanism that reduces body temperature. “Naturally, when the body moves into sleep it begins to reduce its temperature, reaching the lowest point at around 4:00 a.m. When the body returns to its normal temperature, we wake up,” Prof. Haim explains. “After exposure to red light, the body continued to behave naturally, but exposure to blue light led the body to maintain its normal temperature throughout the night — further evidence of damage to our natural biological clock.”

    The most significant finding in terms of the disruption of sleep was that exposure to blue light drastically disrupts the continuity of sleep. Whereas after exposure to red light (at both intensities) people woke up an average of 4.5 times (unnoticed awakenings), following exposure to weak blue light 6.7 awakenings were recorded, rising to as many as 7.6 awakenings following exposure to strong blue light. Accordingly, it is hardly surprising that the participants reported in the questionnaires that the felt more tired and in a worse mood after exposure to blue light.

    “Exposure to screens during the day in general, and at night in particular, is an integral part of our technologically advanced world and will only become more intense in the future. However, our study shows that it is not the screens themselves that damage our biological clock, and therefore our sleep, but the short-wave blue light that they emit. Fortunately various applications are available that filter the problematic blue light on the spectrum and replace it with weak red light, thereby reducing the damage to the suppression of melatonin,” concludes Prof. Haim.


  8. Study looks at drawbacks of binge-watching TV

    August 28, 2017 by Ashley

    From the University of Michigan press release:

    Binge-watching may be a great way for young adults to catch up on multiple episodes of their favorite television series like “The Walking Dead” or “Game of Thrones,” but it comes at a price.

    New research by the University of Michigan and the Leuven School for Mass Communication Research in Belgium found that higher binge-viewing frequency leads to poorer sleep quality, more fatigue and increased insomnia, while regular TV viewing does not.

    “Our study signals that binge viewing is prevalent in young adults and that is may be harmful to their sleep,” said co-author Jan Van den Bulck, U-M professor of communication studies.

    Binge viewing, in which people watch an excessive amount of the same TV program in one sitting, has been on the rise as more American households use streaming services and digital video recorders.

    Researchers surveyed 423 adults between the ages of 18 to 25 in February 2016. They were asked about sleep quality, fatigue and insomnia, as well as the frequency of binge watching programs on a TV, laptop or desktop computer for the last month.

    Most of the sample (81 percent) reported that they had binge-watched. Of that group, nearly 40 percent did it once during the month preceding the study, while 28 percent said they did it a few times. About 7 percent had binge-viewed almost every day during the preceding month. Men binge-watched less frequently than women, but the viewing session nearly doubled that of women.

    Respondents indicated they slept, on average, seven hours and 37 minutes. Those who binge-viewed reported more fatigue and sleep quality compared to those who didn’t binge-watch.

    Liese Exelmans, a researcher at the Leuven School for Mass Communication Research and the study’s lead author, said people might sleep an appropriate amount of time (seven to nine hours for adults), but the quality is not always good.

    “These students have flexible daytime schedules,” she said. “Chances are they are compensating for lost sleep by sleeping in.”

    The study showed that increased cognitive arousal prior to sleep (i.e., being mentally alert) is the mechanism explaining the effects of binge viewing on sleep quality.

    “Bingeable TV shows have plots that keep the viewer tied to the screen,” Exelmans said. “We think they become intensely involved with the content, and may keep thinking about it when they want to go to sleep.”

    A racing heart, or one that beats irregularly, and being mentally alert can create arousal (or pre-sleep arousal) when a person tries to fall asleep. This can lead to poor sleep quality after binge-viewing.

    “This prolongs sleep onset or, in other words, requires a longer period to ‘cool down’ before going to sleep, thus affecting sleep overall,” Exelmans said.

    The Researchers note that binge-watching frequently happens unintentionally. People get absorbed into their shows, watch “just one more episode” and fail to go to bed in a timely manner.

    “They might not intend on watching a lot, but they end up doing so anyway,” Exelmans said.

    Sleep insufficiency has been connected to physical and mental health consequences, including reduced memory function and learning ability, obesity, hypertension and cardiovascular disease.

    “Basically, sleep is the fuel your body needs to keep functioning properly,” Exelmans said. “Based on that research, it’s very important to document the risk factors for poor sleep. Our research suggests that binge viewing could be one of this risk factors.”


  9. Sleep makes it possible for babies to associate words with content, and not with noise

    August 27, 2017 by Ashley

    From the Max Planck Institute for Human Cognitive and Brain Sciences press release:

    While babies sleep, astonishing processes take place in their brains. Scientists at the Max Planck Institute for Human Cognitive and Brain Sciences (MPI CBS) in Leipzig observed that babies succeed in associating a meaning with a word between the age of six and eight months — a capability which until now was known for older children and adults. Memory which is assigned to the meaning of words passes through the same stages during sleep that also happen in typical lexical development: So-called protowords which combine only simultaneously occurring visual and acoustic stimuli become real words that are connected to content.

    The scientists investigated these relations by introducing six- to eight-month-old infants to fantasy objects which they gave fantasy names such as “Bofel” or “Zuser.” Objects that differed only in form or colour were called the same names — just as cats are called “cats” although they differ in their details. The researchers chose these fictitious objects to make sure that the young study participants could not access any existing knowledge.

    From the infants’ brain reaction it was clear that the children could not connect new objects of the same category with the corresponding name. That means they did not recognise a new Bofel as a “Bofel” although it was quite similar to the previously seen Bofel versions. For the babies, every new object-word pair was unknown and unique, they could not yet build a general relation between them.

    This changed after a midday nap. In babies who fell asleep after the learning phases, the brain could differentiate between the right and wrong term for a new object. They had consolidated their knowledge while sleeping. Babies that stayed awake could not manage to do so.

    Interestingly, the children developed two different types of knowledge depending on the duration of sleep. After a half-hour nap they showed a brain reaction which three-month-olds already have after associating a visual stimulus with an acoustic one. During their nap they filtered similar features out of the objects and connected them with the sound of a word. Similar to the three-month-old babies, they perceived the word as a random sound with no meaning.

    Unlike the infants who napped for half an hour, babies that slept for about 50 minutes showed a brain reaction that was previously only known for older children and adults. Here, the so-called N400 component occurred, which signals that incongruous meanings were processed in the brain — whether it be in sentences, word pairs, picture stories or object-word pairs. By means of this component the researchers were able to recognise that the young participants in fact learnt the meaning of the words.

    “Our results demonstrate that children hold real word meanings in their long-term memory much earlier than assumed. Although the brain structures relevant for this type of memory are not fully matured, they can already be used to a distinguishable extent,” explains Angela D. Friederici, director at MPI CBS and senior author of the underlying study which has recently been published in Current Biology.

    In this context, one stage of sleep could be of particular importance: The duration of the second of the four stages of sleep, in particular, seems to have an important influence on the development of lexical memory. “During this light sleep, the transition from a simple early developing form of lexical memory to an advanced later developing form evidently takes place,” says study leader Manuela Friedrich. “These two types of memory which develop during sleep are comparable with those that we know from infant development. Whereas during sleep there are just minutes in between the two types, in typical development there are months.” The formation of memory content in sleep clearly takes place in fast motion.

    “In our study, however, the babies received such a lot of information which they normally pick up within a longer time period,” Manuela Friedrich adds. “But only during sleep, when the child’s brain is disconnected from the outer world, can it filter and save essential relations. Only during the interaction between awake exploration and ordering processes while sleeping can early cognitive and linguistic capabilities develop properly.”


  10. Being bullied may dramatically affect sleep

    August 25, 2017 by Ashley

    From the McLean Hospital press release:

    New research from McLean Hospital neuroscientists shows in an animal model that being bullied can have long-term, dramatic effects on sleep and other circadian rhythm-related functions, symptoms that are characteristic of clinical depression and other stress-induced mental illnesses. The researchers, however, also found that it may be possible to mitigate these effects with the use of an experimental class of drugs that can block stress.

    “While our study found that some stress-related effects on circadian rhythms are short-lived, others are long-lasting,” said William Carlezon, PhD, chief of the Division of Basic Neuroscience and director of the Behavioral Genetics Laboratory at McLean Hospital and senior author of the study. “Identifying these changes and understanding their meaning is an important step in developing methods to counter the long-lasting effects of traumatic experiences on mental health.”

    Stress is known to trigger psychiatric illnesses, including depression and PTSD, and sleep is frequently affected in these conditions. Some people with stress disorders sleep less than normal, while others sleep more than normal or have more frequent bouts of sleep and wakefulness.

    To demonstrate the effects of bullying, the researchers used an animal model simulating the physical and emotional stressors involved in human bullying — chronic social defeat stress.

    For this procedure, a smaller, younger mouse is paired with a larger, older, and more aggressive mouse. When the smaller mouse is placed into the home cage of the larger mouse, the larger mouse instinctively acts to protect its territory.

    In a typical interaction lasting several minutes, the larger mouse chases the smaller mouse, displaying aggressive behavior and emitting warning calls. The interaction ends when the larger mouse pins the smaller mouse to the floor or against a cage wall, establishing dominance by the larger mouse and submission by the smaller mouse.

    The mice are then separated and a barrier is placed between them, dividing the home cage in half. A clear and perforated barrier is used, enabling the mice to see, smell, and hear each other, but preventing physical interactions. The mice remain in this arrangement, with the smaller mouse living under threat from the larger mouse, for the rest of the day. This process is repeated for 10 consecutive days, with a new aggressor mouse introduced each day.

    To collect data continuously and accurately, researchers outfitted the smaller mice with micro-transmitters that are akin to activity trackers used by people to monitor their exercise, heart rate, and sleep. These mice micro-transmitters collected sleep, muscle activity, and body temperature data, which revealed that the smaller mice experienced progressive changes in sleep patterns, with all phases of the sleep-wake cycle being affected. The largest effect was on the number of times the mice went in and out of a sleep phase called paradoxical sleep, which resembles REM (rapid eye movement) sleep in humans, when dreams occur and memories are strengthened. Bullied mice showed many more bouts of paradoxical sleep, resembling the type of sleep disruptions often seen in people with depression. Bullied mice also showed a flattening of body temperature fluctuations, which is also an effect seen in people with depression.

    “Both the sleep and body temperature changes persisted in the smaller mice after they were removed from the physically and emotionally threatening environment, suggesting that they had developed symptoms that look very much like those seen in people with long-term depression,” said Carlezon. “These effects were reduced, however, in terms of both intensity and duration, if the mice had been treated with a kappa-opioid receptor antagonist, a drug that blocks the activity of one of the brain’s own opioid systems.”

    Carlezon explained that these findings not only reveal what traumatic experiences can do to individuals who experience them, but also that we may someday be able to do something to reduce the severity of their effects.

    “This study exemplifies how measuring the same types of endpoints in laboratory animals and humans might hasten the pace of advances in psychiatry research. If we can knock out stress with new treatments, we might be able to prevent some forms of mental illness.”

    The detailed findings of this study are available in the August 9, 2017 issue of the Journal of Neuroscience.

    McLean Hospital is the largest psychiatric affiliate of Harvard Medical School and a member of Partners HealthCare. For more information about McLean, visit mcleanhospital.org or follow the hospital on Facebook or Twitter.