Using an air conditioner in summer may affect sleep quality

Sleep quality may be affected by subtle insensible airflow

February 16, 2017

Science Daily/Toyohashi University of Technology

Using an air conditioner helps people sleep better on sweltering nights. However, researchers found that when airflow is directed at a human body, even at an insensible velocity, it impacts on sleep conditions causing sleeping positions and affects the depth of sleep.

A study by a joint research team including professor Kazuyo Tsuzuki of Toyohashi University of Technology, Department of Architecture and Civil Engineering, National Institute of Advanced Industrial Science and Technology and Asahi Kasei Homes revealed that airflow from an air conditioner (AC) stimulates the human body while sleeping and impacts on sleep conditions even if the mean airflow velocity is lower than an insensible level. It suggests some AC setting may have an unintentional negative impact on sleep quality despite the comfort the person feels.

Urban warming blocks the temperature at night from cooling. It causes sweltering nights and deteriorates sleep quality. However, high-quality sleep can still be realized if the room temperature is controlled effectively with an AC. The general belief is that having the AC on all night is bad for health. Also, quite a few of us experience chills while sleeping and awakening due to cold temperature.

Airflow velocity in the sleeping environment can be configured with the AC. However, no data on airflow velocity measurement or research on the influence of AC airflow have been available.

The research team, led by professor Kazuyo Tsuzuki, had the subjects sleep in two bedrooms set to the same temperature using ACs set at different airflow velocities, then made a comparison of the depth of sleep and body temperature control using electroencephalogram (EEG) measurements as well as subjective reporting by the subjects.

We call the air velocity of 0.2m/s or lower "insensible airflow," in a sense, the person remains unaware of such a low level of airflow. In this study, a comparison was made on the influence of two types of airflow, mean velocity of 0.14 m/s (general AC) and 0.04 m/s (customized AC), both at a room temperature of 26 °C. Subjects felt cooler with the higher airflow velocity during wakefulness and sleep. However, no significant difference was observed in the feeling of comfort, length of sleep depth, skin temperature, rectal temperature or sense of warmth or coolness in each subject before sleeping.

General AC lowers airflow when the room temperature reaches the desired setting and starts increasing the flow again when the temperature is higher. The study compared the correlation between the timing of the airflow starting to blow and body movement, heart rate and waking stage in sleep depth.

The results found that the subjects have significantly greater body movements, an increased heart rate and a higher frequency of waking in the room that has the AC with a mean velocity of 0.14 m/s. This suggests the general AC may have some influence on sleep, as we discovered that subjects roll over or their sleep depth changes the moment cool air blows out.

This study was conducted using healthy adult male subjects. It implies that the cold airflow may have a greater impact on the overall sleep of female and elderly subjects with lower physical strength or a greater sensitivity to cold. The result of this study is expected to be a useful clue as to how to configure the airflow velocity of an AC to create a comfortable sleeping environment.

This research is the result of the study conducted by Professor Kazuyo Tsuzuki at the National Institute of Advanced Industrial Science and Technology.

https://www.sciencedaily.com/releases/2017/02/170216094523.htm

Trouble getting to sleep? Scientists say go camping

February 2, 2017

Science Daily/Cell Press

In our modern times, many of us sit up late into the night, watching TV, fiddling with our smartphones, or reading a book by lamplight. Getting up to the sound of the morning alarm isn't easy. Now, researchers have more evidence to suggest that the solution to these sleeping woes could be as simple as spending more time outdoors in the sun.

"Late circadian and sleep timing in modern society are associated with negative performance and health outcomes such as morning sleepiness and accidents, reduced work productivity and school performance, substance abuse, mood disorders, diabetes, and obesity," says Kenneth Wright at the University of Colorado Boulder. "Our findings demonstrate that living in our modern environments contributes to late circadian timing regardless of season and that a weekend camping trip can reset our clock rapidly."

An earlier study by Wright's team found that our modern exposure to electrical lighting causes about a two-hour delay in our internal clocks, as evidenced by a shift in the normal fluctuations of the hormone melatonin. They found that a week of summer sun shifted those internal clocks back, sending people to bed earlier, without changing how long they slept.

But questions remained: What happens as the season changes from summer to winter? How quickly can our clocks be changed? To find out, in the latest study, they sent another group of five active people camping for a week in the chilly Colorado winter, right around the time of the winter solstice when the days were at their shortest -- no flashlights or cell phones allowed -- and watched what would happen to their sleep and hormonal rhythms.

The data suggest that our modern lifestyles reduce light exposure in the winter by a whopping 13 times. With increased time spent outdoors, people in the study started going to bed at a more reasonable hour. Their internal clocks, measured by the timing of when melatonin levels began to rise in their bodies, shifted more than 2.5 hours earlier. Their sleeping patterns followed these changes in melatonin levels and people went to sleep earlier.

In the new report, Wright and his colleagues also asked whether a camping weekend in the summer was enough to shift the clock, and it was. This time, they sent nine active people camping while another five stayed at home. A weekend spent camping prevented the typical weekend pattern of staying up late and sleeping in and prevented individuals' circadian clocks from being shifted even later.

The findings show that people are responsive to seasonal changes in daylight just as other animals are. While our modern conveniences may leave us out of synch, our clocks can be readily reset with light exposure.

If a person wants to go to bed at an earlier hour, then a weekend spent camping could be just the thing, Wright says. To stay on track, consistency is key. It's best to keep a regular schedule. He also recommends increasing daytime exposure to sunlight and reducing nighttime exposure to electrical lighting. There could be other solutions, too.

"Our findings highlight an opportunity for architectural design to bring in more natural sunlight into the modern built environment and to work with lighting companies to incorporate tunable lighting that would be able to change across the day and night to enhance performance, health, and well-being," he says.

The researchers say they hope to learn just how much sunlight is needed to adjust the clock in one direction or another. They're also interested to explore the connection between light exposure, circadian cycles, and other aspects of our health.

https://www.sciencedaily.com/releases/2017/02/170202123027.htm

Easier to let go: Can depression help people deal with life?

February 2, 2017

Science Daily/Friedrich Schiller University Jena

Patients with depression find it easier to abandon unattainable goals, a psychological study has concluded.

Patients with depression find it easier to abandon unattainable goals, psychological study at the University of Jena shows

"If at first you don't succeed, try, try again!" This saying is drummed into us from a young age, when our tower of building blocks keeps collapsing or we just can't get the hang of riding a bicycle. Perseverance is praised and we are told that only with the right motivation will we be able to achieve the aims we have set ourselves.

"That may hold true in many areas of life, such as work, sport or the family," says Prof. Klaus Rothermund of Friedrich Schiller University Jena (Germany). But an over-ambitious life plan can also prove to be a trap, adds the Professor of General Psychology. This is the case when the goals pursued are unattainable.

"Some people develop depression as a result of such futile efforts," says Rothermund. The fact that the goal remains unattainably distant, however hard a person tries, makes them experience helplessness and suffer from a loss of control. However, this must not inevitably be a psychological dead-end. Depression can actually create opportunities for sufferers, as Psychology student Katharina Koppe and Prof. Rothermund have now demonstrated in a study. In the 'Journal of Behavior Therapy and Experimental Psychiatry' they show that patients with depression are significantly more successful than healthy individuals at letting go of unattainable goals.

Giving up in order to win

And, from a psychological point of view, that is a great advantage. "The one, who gives up, wins," says lead author Katharina Koppe, "even if that sounds paradoxical at first." The ability to disengage, according to the psychologists, represents an important adaptive function of depression. Put simply: if the discrepancy between my personal goal and my current possibilities is too large, I would be better off looking for a more realistic goal and abandoning the old one.

In their study, the Jena University psychologists gave patients with depression and healthy participants the simple task of solving anagrams. These are words in which the letters are in the wrong order. For example, the anagram SIEGOT should be rearranged to make EGOIST. The participants had to solve as many anagrams as possible within a specific time. What the participants did not know was that some of the anagrams were unsolvable, as it was impossible to rearrange them to form a meaningful word. "These unsolvable tasks represented unattainable goals, which it was necessary to give up as soon as possible in order to use the time effectively," explains Katharina Koppe. It emerged from the experiment that the patients with depression spent less time in total on the unsolvable anagrams than the control group, while the time spent working on the solvable tasks did not differ between the two groups.

Crisis as an opportunity for personal development

Although this test involves a very simple type of task, which can doubtlessly not be equated one-to-one with other challenges of daily life, the psychologists do see in it important indications for a change in our view of depression. "The general lack of motivation that is typical of many patients with depression apparently gives rise to a greater ability to abandon goals, and one could use this in therapy," Prof. Rothermund says.

One strategy could be to identify the unattainable goals that have led to the patients being depressed, and then specifically support the patients in disengaging themselves. "If we stop seeing depression simply as a psychological burden, which just needs to be removed through therapy, we might also be able to use the patient's crisis as an opportunity for personal development," says Katharina Koppe. First of all, however, considerably more research is needed on this topic.

https://www.sciencedaily.com/releases/2017/02/170202085847.htm

Creative people sleep more, later, and less well

January 26, 2017

Science Daily/University of Haifa

The study compared art students and social science students, and found that art student sleep more hours, but reported more sleep disturbance and daytime dysfunction.

Do you ever dream of becoming the next Picasso? A new study at the University of Haifa comparing art and social science students has found that visually creative students evaluate their sleep as of lower quality. "Visually creative people reported disturbed sleep leading to difficulties in daytime functioning," explains doctorate student Neta Ram-Vlasov, one of the authors of the study. "In the case of verbally creative people, we found that they sleep more hours and go to sleep and get up later. In other words, the two types of creativity were associated with different sleep patterns. This strengthens the hypothesis that the processing and expression of visual creativity involves different psychobiological mechanisms to those found in verbal creativity."

One of the leading approaches to the subject defines creativity according to four characteristics: fluency -- the ability to produce a wide range of ideas; flexibility -- the ability to switch easily between different thought patterns in order to produce this wide range of ideas; originality -- the unique quality of the idea relative to the ideas in the environment; and elaboration -- the ability to develop each idea separately.

The current study was undertaken by Prof. Tamar Shochat of the Department of Nursing and doctorate student Neta Ram-Vlasov of the Graduate School of Creative Art Therapies at the University of Haifa, together with Amit Green from the Sleep Institute at Assuta Medical Center and Prof. Orna Tzischinsky from the Department of Psychology at Yezreel Valley College. The researchers sought to understand how two types of creativity -- visual and verbal -- influence objective aspects of sleep such as duration and timing (indexes such as the time of falling asleep and waking up), and subjective aspects -- sleep quality.

Thirty undergraduate students from seven academic institutions participated in the study, half of whom were majoring only in art and half of whom were majoring only in the social sciences. During the study, the participants underwent overnight electrophysiological sleep recordings, wore a wrist activity monitor (a device that measures sleep objectively), and completed a sleep monitoring diary and a questionnaire on sleep habits in order to measure the pattern and quality of sleep. They also undertook visual and verbal creativity tests.

The findings show that among all the participants, the higher the level of visual creativity, the lower the quality of their sleep. This was manifested in such aspects as sleep disturbances and daytime dysfunction. The researchers also found that the higher the participants' level of verbal creativity, the more hours they slept and the later they went to sleep and woke up. A comparison between the sleep patterns of art students and non-art students found that art students sleep more, but this in no way guarantees quality sleep: art students evaluated their sleep as of lower quality and reported more sleep disturbances and daytime dysfunction than the non-art students. The researchers add that possible explanations can be offered for the connections found between the two types of creativity and sleep patterns. Further studies may help determine whether creativity influences sleep or vice versa (or perhaps neither is the case). "It is possible that a 'surplus' of visual creativity makes the individual more alert, and this could lead to sleep disturbances," the researchers suggested. "On the other hand, it is possible that it is protracted sleep among verbally creativity individuals that facilitates processes that support the creative process while they are awake. In any case, these findings are further evidence of the fact that creativity is not a uniform concept. Visual creativity is activated by -- and activates -- different cerebral mechanisms than verbal creativity."

https://www.sciencedaily.com/releases/2017/01/170126082022.htm

What is good quality sleep? National Sleep Foundation provides guidance

January 23, 2017

Science Daily/National Sleep Foundation

The National Sleep Foundation recently released the key indicators of good sleep quality, as established by a panel of experts.

Given the precipitous increase in the use of sleep technology devices, the key findings are timely and relevant. This information complements the data these devices provide, helping millions of consumers interpret their sleep patterns. The report comes as the first step in NSF's effort to spearhead defining the key indicators of good sleep quality. They key determinants of quality sleep are included in a report published in Sleep Health. They include:

* Sleeping more time while in bed (at least 85 percent of the total time)

* Falling asleep in 30 minutes or less

* Waking up no more than once per night; and

* Being awake for 20 minutes or less after initially falling asleep.

Multiple rounds of consensus voting on the determinants led to the key findings, which have since been endorsed by the American Association of Anatomists, American Academy of Neurology, American Physiological Society, Gerontological Society of America, Human Anatomy and Physiology Society, Society for Research on Biological Rhythms, Society for Research of Human Development, and Society for Women's Health Research.

Max Hirshkowitz, PhD, DABSM, Chairman of the Board of Directors of the NSF stated, "Millions of Americans are sleep technology users. These devices provide a glimpse into one's sleep universe, which is otherwise unknown. The National Sleep Foundation's guidelines on sleep duration, and now quality, make sense of it all -- providing consumers with the resources needed to understand their sleep. These efforts help to make sleep science and technology more accessible to the general public that is eager to learn more about its health in bold new ways."

Notably, NSF's recent Sleep Health Index® revealed that as many as 27 percent of people take longer than 30 minutes, on average, to fall asleep. With wider use of sleep technology and the context provided by NSF's guidelines, consumers can better gauge and even improve their sleep. Furthermore, NSF's recommendations are instrumental to the continued development of such consumer technologies. The report also highlights areas where research is needed to identify and further delineate additional indicators of good sleep quality across age groups.

"In the past, we defined sleep by its negative outcomes including sleep dissatisfaction, which were useful for identifying underlying pathology. Clearly this is not the whole story. With this initiative, we are now on a better course towards defining sleep health," noted Maurice Ohayon, MD, DSc, PhD, Director of the Stanford Sleep Epidemiology Research Center.

https://www.sciencedaily.com/releases/2017/01/170123094549.htm

Older, fitter adults experience greater brain activity while learning

January 13, 2017

Science Daily/Boston University Medical Center

Older adults who experience good cardiac fitness may be also keeping their brains in good shape as well. In what is believed to be the first study of its kind, older adults who scored high on cardiorespiratory fitness (CRF) tests performed better on memory tasks than those who had low CRF. Further, the more fit older adults were, the more active their brain was during learning.

In what is believed to be the first study of its kind, older adults who scored high on cardiorespiratory fitness (CRF) tests performed better on memory tasks than those who had low CRF. Further, the more fit older adults were, the more active their brain was during learning. These findings appear in the journal Cortex. Difficulty remembering new information represents one of the most common complaints in aging and decreased memory performance is one of the hallmark impairments in Alzheimer's disease.

Healthy young (18-31 years) and older adults (55-74 years) with a wide range of fitness levels walked and jogged on a treadmill while researchers assessed their cardiorespiratory fitness by measuring the ratio of inhaled and exhaled oxygen and carbon dioxide. These participants also underwent MRI scans which collected images of their brain while they learned and remembered names that were associated with pictures of unfamiliar faces.

The researchers found that older adults, when compared to younger adults, had more difficulty learning and remembering the correct name that was associated with each face. Age differences in brain activation were observed during the learning of the face-name pairs, with older adults showing decreased brain activation in some regions and increased brain activation in others. However, the degree to which older adults demonstrated these age-related changes in memory performance and brain activity largely depended on their fitness level. In particular, high fit older adults showed better memory performance and increased brain activity patterns compared to their low fit peers. The increased brain activation in the high fit older adults was observed in brain regions that show typical age-related decline, suggesting fitness may contribute to brain maintenance. Higher fit older adults also had greater activation than young adults in some brain regions, suggesting that fitness may also serve a compensatory role in age-related memory and brain decline.

According to the researchers this study highlights that CRF is not only important for physical health, but is also associated with brain function and memory performance. "Importantly, CRF is a modifiable health factor that can be improved through regular engagement in moderate to vigorous sustained physical activity such as walking, jogging, swimming, or dancing. Therefore, starting an exercise program, regardless of one's age, can not only contribute to the more obvious physical health factors, but may also contribute to memory performance and brain function," explained corresponding author Scott Hayes, PhD, assistant professor of psychiatry at Boston University School of Medicine and the Associate Director of the Neuroimaging Research for Veterans Center at the VA Boston Healthcare System.

The researchers caution that maintaining high levels of fitness through physical activity will not entirely eliminate or cure age- or Alzheimer's disease related decline, but it may slow down the decline. Future studies following individuals' fitness and physical activity levels, memory, and brain function over the course of years would more directly address this issue.

https://www.sciencedaily.com/releases/2017/01/170113155426.htm

Depression as hard on the heart as obesity and cholesterol

January 13, 2017

Science Daily/Helmholtz Zentrum München - German Research Center for Environmental Health

Depression poses a risk for cardiovascular diseases in men that is just as great as that posed by high cholesterol levels and obesity.

According to the World Health Organisation WHO, 350 million people worldwide are affected by depression. But the mental state is not all that is affected, however, and depression can also compromise the body. "Meanwhile there is little doubt that depression is a risk factor for cardiovascular diseases," explains Karl-Heinz Ladwig. He is group leader at the Institute of Epidemiology II at the Helmholtz Zentrum München, professor of psychosomatic medicine at TUM's Klinikum rechts der Isar as well as scientist of DZHK. "The question now is: What is the relationship between depression and other risk factors like tobacco smoke, high cholesterol levels, obesity or hypertension -- how big a role does each factor play?"

In order to examine this question, Ladwig and his team analyzed data from 3,428 male patients between the ages of 45 and 74 years and observed their development over a period of ten years. "The work is based on a prospective population-based data set from the MONICA/KORA study that, with a total term of up to 25 years, is one of the few large studies in Europe that allows such an analysis," reports the statistician Dr. Jens Baumert of Helmholtz Zentrum München, who was also involved in the publication.

Investigate depression in high-risk patients

In their analyses, the scientists compared the impact of depression with the four major risk factors. "Our investigation shows that the risk of a fatal cardiovascular disease due to depression is almost as great as that due to elevated cholesterol levels or obesity," Ladwig summarizes. The results show that only high blood pressure and smoking are associated with a greater risk. Viewed across the population, depression accounts for roughly 15 percent of the cardiovascular deaths. "That is comparable to the other risk factors, such as hypercholesterolemia, obesity and smoking," Ladwig states. These factors cause 8.4 to 21.4 percent of the cardiovascular deaths.

"We invested a great deal of time in this work, just due to the long observation period," says study leader Ladwig. But the effort paid off: "Our data show that depression has a medium effect size within the range of major, non-congenital risk factors for cardiovascular diseases." Ladwig accordingly proposes consequences here: "In high risk patients, the diagnostic investigation of co-morbid depression should be standard. This could be registered with simple means."

https://www.sciencedaily.com/releases/2017/01/170113085931.htm

Study unveils how stress may increase risk of heart disease and stroke

January 11, 2017

Science Daily/The Lancet

Heightened activity in the amygdala - a region of the brain involved in stress - is associated with a greater risk of heart disease and stroke, according to a new study.

While more research and larger studies are needed to confirm the mechanism, the researchers suggest that these findings could eventually lead to new ways to target and treat stress-related cardiovascular risk.

Smoking, high blood pressure and diabetes are well-known risk factors for cardiovascular disease and chronic psychosocial stress could also be a risk factor.

Previously, animal studies identified a link between stress and higher activity in the bone marrow and arteries, but it has remained unclear whether this also applies to humans. Other research has also shown that the amygdala is more active in people with post-traumatic stress disorder (PTSD), anxiety and depression, but before this study no research had identified the region of the brain that links stress to the risk of heart attack and stroke.

In this study, 293 patients were given a combined PET/CT scan to record their brain, bone marrow and spleen activity and inflammation of their arteries. The patients were then tracked for an average of 3.7 years to see if they developed cardiovascular disease. In this time 22 patients had cardiovascular events including heart attack, angina, heart failure, stroke and peripheral arterial disease.

Those with higher amygdala activity had a greater risk of subsequent cardiovascular disease and developed problems sooner than those with lower activity.

The researchers also found that the heightened activity in the amygdala was linked to increased bone marrow activity and inflammation in the arteries, and suggest that this may cause the increased cardiovascular risk. The authors suggest a possible biological mechanism, whereby the amygdala signals to the bone marrow to produce extra white blood cells, which in turn act on the arteries causing them to develop plaques and become inflamed, which can cause heart attack and stroke.

In a small sub-study, 13 patients who had a history of PTSD also had their stress levels assessed by a psychologist, underwent a PET scan and had their levels of C-reactive protein -- a protein that indicates levels of inflammation in the body -- measured. Those who reported the highest levels of stress had the highest levels of amygdala activity along with more signs of inflammation in their blood and the walls of their arteries.

"Our results provide a unique insight into how stress may lead to cardiovascular disease. This raises the possibility that reducing stress could produce benefits that extend beyond an improved sense of psychological wellbeing," said lead author Dr Ahmed Tawakol, Massachusetts General Hospital and Harvard Medical School, USA. "Eventually, chronic stress could be treated as an important risk factor for cardiovascular disease, which is routinely screened for and effectively managed like other major cardiovascular disease risk factors."

The researchers note that the activity seen in the amygdala may contribute to heart disease through additional mechanisms, since the extra white blood cell production and inflammation in the arteries do not account for the full link. They also say that more research is needed to confirm that stress causes this chain of events as the study was relatively small.

Writing in a linked Comment, Dr Ilze Bot, Leiden Academic Centre for Drug Research, Leiden University, The Netherlands, said: "In the past decade, more and more individuals experience psychosocial stress on a daily basis. Heavy workloads, job insecurity, or living in poverty are circumstances that can result in chronically increased stress, which in turn can lead to chronic psychological disorders such as depression." She says that more research is needed to confirm the mechanism but concludes: "These clinical data establish a connection between stress and cardiovascular disease, thus identifying chronic stress as a true risk factor for acute cardiovascular syndromes, which could, given the increasing number of individuals with chronic stress, be included in risk assessments of cardiovascular disease in daily clinical practice."

https://www.sciencedaily.com/releases/2017/01/170111183921.htm

Music in the brain: The first imaging genetic study linking dopaminergic genes to music

December 21, 2016

Science Daily/Aarhus University

Sounds, such as music and noise, are capable of reliably affecting individuals' moods and emotions, possibly by regulating brain dopamine, a neurotransmitter strongly involved in emotional behavior and mood regulation. However, the relationship of sound environments with mood and emotions is highly variable across individuals. A putative source of variability is genetic background, a study shows.

However, the relationship of sound environments with mood and emotions is highly variable across individuals. A putative source of variability is genetic background.

In this regard, a new imaging genetics study directed by Professor Elvira Brattico from Aarhus University and conducted in two Italian hospitals in collaboration with the University of Helsinki (Finland) has provided the first evidence that the effects of music and noise on affective behavior and brain physiology are associated with genetically determined dopamine functionality.

In particular, this study, published in the journal Neuroscience, revealed that a functional variation in dopamine D2 receptor gene (DRD2 rs1076560) modulates the impact of music as opposed to noise on mood states and emotion-related prefrontal and striatal brain activity, evidencing a differential susceptibility for the affect-modulatory effects of music and noise on the GG and GT genotypes.

In more details, results showed mood improvement after music exposure in GG subjects and mood deterioration after noise exposure in GT subjects. Moreover, the music as opposed to noise environment decreased the striatal activity of GT subjects as well as the prefrontal activity of GG subjects while processing emotional faces.

These results are novel in identifying a biological source of variability in the impact of sound environments on emotional responses. The first author of the study, Tiziana Quarto, Ph.D. student at University of Helsinki under supervision of Prof. Brattico, further comments:

"Our approach allowed the observation of the link between genes and phenotypes via a true biological path that goes from functional genetic variations (for which the effects on molecular function is known) to brain physiology subtending behavior. The use of this approach is especially important when the investigated behavior is complex and very variable across subjects, because this means that many biological factors are involved."

"This study represents the first use of the imaging genetics approach in the field of music and sounds in general. We are really excited about our results because they suggest that even a non-pharmacological intervention such as music, might regulate mood and emotional responses at both the behavioral and neuronal level," says Professor Elvira Brattico.

"More importantly, these findings encourage the search for personalized music-based interventions for the treatment of brain disorders associated with aberrant dopaminergic neurotransmission as well as abnormal mood and emotion-related brain activity."

https://www.sciencedaily.com/releases/2016/12/161221125458.htm

Here's why you don't feel jet-lagged when you run a fever

December 22, 2016

Science Daily/Johns Hopkins Medicine

A clump of just a few thousand brain cells, no bigger than a mustard seed, controls the daily ebb and flow of most bodily processes in mammals -- sleep/wake cycles, most notably. Now, scientists report direct evidence in mice for how those cell clusters control sleep and relay light cues about night and day throughout the body.

https://images.sciencedaily.com/2016/12/161222130410_1_540x360.jpg

The area of the brain known as the suprachiasmatic nucleus (SCN) is the body's master clock. It uses light to synchronize the body's rhythms with night and day. It directly controls sleep/wake cycles and indirectly controls other processes, like hunger and thirst, by controlling the body's thermostat, the preoptic area of the brain.

Credit: Johns Hopkins Medicine

A clump of just a few thousand brain cells, no bigger than a mustard seed, controls the daily ebb and flow of most bodily processes in mammals -- sleep/wake cycles, most notably. Now, Johns Hopkins scientists report direct evidence in mice for how those cell clusters control sleep and relay light cues about night and day throughout the body.

A summary of their study of the brain region known as the suprachiasmatic nucleus, or SCN, will be published online in the journal Current Biology on Dec. 22.

"Light has a strong, negative and direct effect on sleep in humans. We experience this every evening when we turn out the lights before we go to bed and every morning when we open the curtains to let light in. However, very little was known about how this happens. Learning that the SCN is indeed required for light to directly regulate sleep is an important piece of the circadian rhythm puzzle," says Seth Blackshaw, Ph.D., professor of neuroscience at the Johns Hopkins University School of Medicine. "Our chances of finding treatments for people with sleep disorders, or just jet lag, improve the more we understand the details about how sleep is controlled."

Blackshaw says scientists have known for a while that the SCN functions as a master clock to synchronize sleep and other so-called circadian rhythms in humans and other mammals. But its importance in the more immediate regulation of sleep, like when a bright light wakes someone up, remained debatable because the experiments needed to show its role in a living animal were essentially impossible. "If you surgically removed the SCN in mice, their sleeping and waking were no longer immediately influenced by light, but you can't remove the SCN without also severing the optic nerve that brings light information to it from the retina. So no one knew if this resistance to light was due to the missing SCN or the missing optic nerve," says Blackshaw.

In experiments first reported several years ago, Blackshaw's team found a way to disrupt the normal function of the SCN without physically removing it and damaging the optic nerve. The researchers were trying to identify genes involved in the development of the mouse hypothalamus, the area of the brain that includes the SCN. They identified one such gene, dubbed LHX1, that seemed to be the earliest to "turn on" in the development of the fetal SCN.

For the new round of experiments, the scientists used a customized genetic tool to delete LHX1 just from cells that make up the SCN. They found that the mice experienced severely disrupted circadian rhythms, although they could still be weakly synchronized to light cycles. And the cells of the SCN no longer produced six small signaling proteins known to coordinate and reinforce their efforts, a biochemical process known as coupling.

Whether the mice were kept in constant light, constant darkness or normal cycles of both, their sleep times and duration became random. Cumulatively, they slept for the same amount of time, about 12 hours each 24-hour period, like normal mice, but there was no pattern to the cycle.

"This experiment showed that the SCN is critical to light's immediate effect on sleep," says Blackshaw.

The scientists also noticed that in the SCN-impaired mice, core body temperatures didn't cycle normally. The average body temperature for humans is 37 degrees Celsius, but it fluctuates throughout the day by about 1 degree Celsius, being highest in the afternoon and lowest just before dawn. A similar pattern occurs in mice. These small temperature fluctuations can have a big influence on processes that occur outside the brain that are also under circadian control, such as glucose usage and fat storage, and it has been speculated that they may be the main way by which the SCN controls these bodily rhythms.

In contrast, one of the hallmarks of the body's circadian processes, including cycles in core body temperature, is that they aren't generally disturbed by large temperature changes. "Otherwise, you would feel jet-lagged every time you got a fever," says Blackshaw. But it wasn't clear from mouse experiments if the SCN was responsible for this resistance to strong temperature changes in living animals. Normal SCN cells in the lab keep cycling in synchrony without regard to temperature pulses, but research from another group showed that they could be "reset" by temperature changes if they could no longer signal to each other.

Knowing that the SCN cells in their LHX1-deficient mice were similarly impaired, a graduate student in Blackshaw's lab, Joseph Bedont, reasoned that their mice might now be able to return to normal temperature cycles if given pulses of heat.

To try that, they injected the mice -- kept in the dark -- with a molecule found in bacterial cell whttps://www.sciencedaily.com/releases/2016/12/161221125458.htmalls, which makes them run a fever in response to the perceived threat. Fever is a first-line infection fighter in humans as well. As suspected, their regular core temperature cycling came back.

"These results suggest that the SCN is indeed responsible for the temperature resistance of circadian rhythms in live animals, and it shows us how important SCN coupling is," says Blackshaw. "It also bolsters the idea that the body's other physiologic cycles, such as hunger and hormone secretion, are synchronized by the SCN through its regulation of core body temperature."

Additional experiments identified several molecules that may be directing these vital signals. The Blackshaw team plans to follow up by studying each one to determine their roles. With that information, drug developers will have a better idea which component to target and how. To treat jet lag, for example, Blackshaw says that one hypothetical option would be to briefly block LHX1 so that the SCN cells uncouple and become easier to reset, either by light or temperature. But no one knows yet if that plan would produce undesirable side effects or the desired outcomes.

https://www.sciencedaily.com/releases/2016/12/161222130410.htm

Rhythm of breathing affects memory, fear

Breathing is not just for oxygen; it's also linked to brain function, behavior

December 7, 2016

Science Daily/Northwestern University

The rhythm of breathing creates electrical activity in the human brain that enhances emotional judgments and memory recall, scientists have discovered for the first time. These effects on behavior depend critically on whether you inhale or exhale and whether you breathe through the nose or mouth.

These effects on behavior depend critically on whether you inhale or exhale and whether you breathe through the nose or mouth.

In the study, individuals were able to identify a fearful face more quickly if they encountered the face when breathing in compared to breathing out. Individuals also were more likely to remember an object if they encountered it on the inhaled breath than the exhaled one. The effect disappeared if breathing was through the mouth.

"One of the major findings in this study is that there is a dramatic difference in brain activity in the amygdala and hippocampus during inhalation compared with exhalation," said lead author Christina Zelano, assistant professor of neurology at Northwestern University Feinberg School of Medicine. "When you breathe in, we discovered you are stimulating neurons in the olfactory cortex, amygdala and hippocampus, all across the limbic system."

The study was published Dec. 6 in the Journal of Neuroscience. The senior author is Jay Gottfried, professor of neurology at Feinberg.

Northwestern scientists first discovered these differences in brain activity while studying seven patients with epilepsy who were scheduled for brain surgery. A week prior to surgery, a surgeon implanted electrodes into the patients' brains in order to identify the origin of their seizures. This allowed scientists to acquire electro-physiological data directly from their brains. The recorded electrical signals showed brain activity fluctuated with breathing. The activity occurs in brain areas where emotions, memory and smells are processed.

This discovery led scientists to ask whether cognitive functions typically associated with these brain areas -- in particular fear processing and memory -- could also be affected by breathing.

The amygdala is strongly linked to emotional processing, in particular fear-related emotions. So scientists asked about 60 subjects to make rapid decisions on emotional expressions in the lab environment while recording their breathing. Presented with pictures of faces showing expressions of either fear or surprise, the subjects had to indicate, as quickly as they could, which emotion each face was expressing.

When faces were encountered during inhalation, subjects recognized them as fearful more quickly than when faces were encountered during exhalation. This was not true for faces expressing surprise. These effects diminished when subjects performed the same task while breathing through their mouths. Thus the effect was specific to fearful stimuli during nasal breathing only.

In an experiment aimed at assessing memory function -- tied to the hippocampus -- the same subjects were shown pictures of objects on a computer screen and told to remember them. Later, they were asked to recall those objects. Researchers found that recall was better if the images were encountered during inhalation.

The findings imply that rapid breathing may confer an advantage when someone is in a dangerous situation, Zelano said.

"If you are in a panic state, your breathing rhythm becomes faster," Zelano said. "As a result you'll spend proportionally more time inhaling than when in a calm state. Thus, our body's innate response to fear with faster breathing could have a positive impact on brain function and result in faster response times to dangerous stimuli in the environment."

Another potential insight of the research is on the basic mechanisms of meditation or focused breathing. "When you inhale, you are in a sense synchronizing brain oscillations across the limbic network," Zelano noted.

Video: https://www.youtube.com/watch?v=1KNn0NYjMWg

https://www.sciencedaily.com/releases/2016/12/161207093034.htm