Healthy heart equals healthy brain

March 16, 2016
Science Daily/American Heart Association
Achieving the metrics that define a healthy heart may translate to healthier brain function as people age. More ideal cardiovascular health measures meant less decline in brain processing speed and, to some extent, thinking ability and memory.
https://images.sciencedaily.com/2016/03/160316194211_1_540x360.jpg
Image of the human heart.
Credit: Copyright American Heart Association

Researchers studied a racially diverse group of older adults and found that having more ideal cardiovascular health factors was associated with better brain processing speed at the study's start and less cognitive decline approximately six years later.

The researchers from the University of Miami and Columbia University used the American Heart Association's "Life's Simple Seven®" definition of cardiovascular health, which includes tobacco avoidance, ideal levels of weight, physical activity, healthy diet, blood pressure, cholesterol and glucose.

"Achieving the health metrics of Life's Simple 7® is associated with a reduced risk of strokes and heart attacks, even among the elderly. And the finding that they may also impact cognitive, or brain function underscores the importance of measuring, monitoring and controlling these seven factors by patients and physicians," said Hannah Gardener, Sc.D., the study's lead author and assistant scientist in neurology at the Miller School of Medicine, University of Miami, in Florida.

At the beginning of the study, 1,033 participants in the Northern Manhattan Study (average age 72; 65 percent Hispanic, 19 percent black and 16 percent white), were tested for memory, thinking and brain processing speed. Brain processing speed measures how quickly a person is able to perform tasks that require focused attention. Approximately six years later, 722 participants repeated the cognitive testing, which allowed researchers to measure performance over time.

The researchers found:

Having more ideal cardiovascular health factors was associated with better brain processing speed at the initial assessment.
The association was strongest for being a non-smoker, having ideal fasting glucose and ideal weight.
Having more cardiovascular health factors was associated with less decline over time in processing speed, memory and executive functioning. Executive
function in the brain is associated with focusing, time management and other cognitive skills.
While this study suggests achieving ideal cardiovascular health measures is beneficial to brain function, future studies are needed to determine the value of routinely assessing and treating risk factors, such as high blood pressure, in order to reduce brain function decline.

Gardener said similar studies in race and ethnically diverse populations, with different profiles of educational attainment, literacy and employment status, are needed to generalize the findings to other populations.

"In addition, further study is needed to identify the age ranges, or periods over the life course, during which cardiovascular health factors and behaviors may be most influential in determining late-life cognitive impairment, and how behavioral and health modifications may influence cognitive performance and mitigate decline over time."
https://www.sciencedaily.com/releases/2016/03/160316194211.htm

Sleep suppresses brain rebalancing

March 21, 2016
Science Daily/Brandeis University
Why humans and other animals sleep is one of the remaining deep mysteries of physiology. One prominent theory in neuroscience is that sleep is when the brain replays memories "offline" to better encode them ("memory consolidation").

A prominent and competing theory is that sleep is important for re-balancing activity in brain networks that have been perturbed during learning while awake. Such "rebalancing" of brain activity involves homeostatic plasticity mechanisms that were first discovered at Brandeis University, and have been thoroughly studied by a number of Brandeis labs including the lab of Brandeis professor of biology Gina Turrigiano.

Now, a study from the lab just published in the journal Cell shows that these homeostatic mechanisms are indeed gated by sleep and wake, but in the opposite direction from that theorized previously: homeostatic brain rebalancing occurs exclusively when animals are awake, and is suppressed by sleep.

These findings raise the intriguing possibility that different forms of brain plasticity -- for example those involved in memory consolidation and those involved in homeostatic rebalancing -- must be temporally segregated from each other to prevent interference.

The requirement that neurons carefully maintain an average firing rate, much like the thermostat in a house senses and maintains temperature, has long been suggested by computational work. Without homeostatic ("thermostat-like") control of firing rates, models of neural networks cannot learn and drift into states of epilepsy-like saturation or complete quiescence.

Much of the work in discovering and describing candidate mechanisms continues to be conducted at Brandeis. In 2013, the Turrigiano lab provided the first in vivo evidence for firing rate homeostasis in the mammalian brain. Lab members recorded the activity of individual neurons in the visual cortex of freely behaving rat pups for 8 hours per day across a nine-day period during which vision through one eye was occluded.

The activity of neurons initially dropped, but over the next four days, firing rates came back to basal levels despite the visual occlusion. In essence, these experiments confirmed what had long been suspected -- the activity of neurons in intact brains is indeed homeostatically governed.

Due to the unique opportunity to study a fundamental mechanism of brain plasticity in an unrestrained animal, the lab has been probing the possibility of an intersection between an animal's behavior and homeostatic plasticity. In order to truly evaluate possible circadian and behavioral influences on neuronal homeostasis, it was necessary to capture the entire 9-day experiment, rather than evaluate snapshots of each day.

For this work, the Turrigiano Lab had to find creative computational solutions to recording many terabytes of data necessary to follow the activity of single neurons without interruption for more than 200 hours.

Ultimately, these data revealed that the homeostatic regulation of neuronal activity in the cortex is gated by sleep and wake states. In a surprising and unpredicted twist, the homeostatic recovery of activity occurred almost exclusively during periods of activity and was inhibited during sleep. Prior predictions either assumed no role for behavioral state, or that sleeping would account for homeostasis.

Finally, the lab established evidence for a causal role for active waking by artificially enhancing natural waking periods during the homeostatic rebound. When animals were kept awake, homeostatic plasticity was further enhanced.

This finding opens doors onto a new field of understanding the behavioral, environmental, and circadian influences on homeostatic plasticity mechanisms in the brain. Some of the key questions that immediately beg to be answered include:

What it is about sleep that precludes the expression of homeostatic plasticity?

How is it possible that mechanisms requiring complex patterns of transcription, translation, trafficking, and modification can be modulated on the short timescales of behavioral state-transitions in rodents?

And finally, how generalizable is this finding? As homeostasis is bidirectional, does a shift in the opposite direction similarly require wake or does the change in sign allow for new rules in expression?
https://www.sciencedaily.com/releases/2016/03/160321200439.htm

Is moderate drinking really good for you? Jury's still out

March 22, 2016
Science Daily/Journal of Studies on Alcohol and Drugs
https://images.sciencedaily.com/2016/03/160322080515_1_540x360.jpg
We analyzed 87 published studies on alcohol and death from all causes. This research suggests we should be skeptical of claims that alcohol consumption offers health benefits.
Credit: University of Victoria, Centre for Addictions Research of BC

Many people believe a glass of wine with dinner will help them live longer and healthier--but the scientific evidence is shaky at best, according to a new research analysis. The findings, published in the March 2016 issue of the Journal of Studies on Alcohol and Drugs, may sound surprising: Countless news stories have reported on research tying moderate drinking to a range of health benefits--including a lower heart disease risk and a longer life.

But the new analysis took a deeper look at those studies, 87 in all. And it found that many were flawed, with designs suggesting benefits where there were likely none.

A key issue is how studies have defined "abstainers," explained Tim Stockwell, Ph.D., the lead researcher on the analysis and director of the University of Victoria's Centre for Addictions Research in British Columbia, Canada.

Most often, studies have compared moderate drinkers (people who have up to two drinks per day) with "current" abstainers. The problem is that this abstainer group can include people in poor health who've cut out alcohol.

"A fundamental question is, who are these moderate drinkers being compared against?" Stockwell said.

When his team corrected for those abstainer "biases" and certain other study-design issues, moderate drinkers no longer showed a longevity advantage. Further, only 13 of the 87 studies avoided biasing the abstainer comparison group--and these showed no health benefits.

What's more, Stockwell said, before those corrections were made, it was actually "occasional" drinkers--people who had less than one drink per week--who lived the longest. And it's unlikely that such an infrequent drinking would be the reason for their longevity.

"Those people would be getting a biologically insignificant dose of alcohol," Stockwell said.

In addition, he noted, studies have linked moderate drinking to an implausibly wide range of health benefits. Compared with abstainers, for instance, moderate drinkers have shown lower risks of deafness and even liver cirrhosis.

"Either alcohol is a panacea," Stockwell said, "or moderate drinking is really a marker of something else."

The study did not look at whether certain types of alcohol, such as red wine, are tied to longer life. But if that were the case, Stockwell said, it would be unlikely that the alcohol content itself deserved the credit.

"There's a general idea out there that alcohol is good for us, because that's what you hear reported all the time," Stockwell said. "But there are many reasons to be skeptical."
https://www.sciencedaily.com/releases/2016/03/160322080515.htm

Is there a link between oral health and the rate of cognitive decline?

April 1, 2016
Science Daily/Wiley
Better oral hygiene and regular dental visits may play a role in slowing cognitive decline as people age, although evidence is not definitive enough to suggest that one causes the other. New findings come from the first systematic review of studies focused on oral health and cognition -- two important areas of research as the older adult population continues to grow, with some 36 percent of people over age 70 already living with cognitive impairments.

Researchers have questioned whether an association exists between oral health and cognitive status for older adults. "Clinical evidence suggests that the frequency of oral health problems increases significantly in cognitively impaired older people, particularly those with dementia," said Bei Wu, PhD, of Duke University's School of Nursing in Durham, NC. "In addition, many of the factors associated with poor oral health--such as poor nutrition and systemic diseases like diabetes and cardiovascular disease--are also associated with poor cognitive function."

To look for a link between oral health and cognitive status, Dr. Wu and her colleagues analyzed relevant cross-sectional (data collected at one specific point in time) and longitudinal (data collected over an extended period of time) studies published between 1993 and 2013.

Some studies found that oral health measures such as the number of teeth, the number of cavities, and the presence of periodontal disease (also known as "gum disease") were associated with an increased risk of cognitive decline or dementia, while others studies were unable to confirm any association. Researchers were also quick to note that findings based on the number of teeth or cavities are conflicting, and limited studies suggest that periodontal conditions such as gingivitis are associated with poorer cognitive status or cognitive decline.

"There is not enough evidence to date to conclude that a causal association exists between cognitive function and oral health," said Dr. Wu. "For future research, we recommend that investigators gather data from larger and more population representative samples, use standard cognitive assessments and oral health measures, and use more sophisticated data analyses."
https://www.sciencedaily.com/releases/2016/04/160401073706.htm

Choir singing boosts immune system activity in cancer patients and carers Singing in a choir for just 1 hour causes physiological changes in people affected by cancer

April 4, 2016
Science Daily/ecancermedicalscience
Singing in a choir for just one hour boosts levels of immune proteins in people affected by cancer, reduces stress and improves mood, which in turn could have a positive impact on overall health, a new study has found.

The research raises the possibility that singing in choir rehearsals could help to put people in the best possible position to receive treatment, maintain remission and support cancer patients.

The study tested 193 members of five different choirs. Results showed that singing for an hour was associated with significant reductions in stress hormones, such as cortisol, and increases in quantities of cytokines -- proteins of the immune system -- which can boost the body's ability to fight serious illness.

Dr Ian Lewis, Director of Research and Policy at Tenovus Cancer Care and co-author of the research, said: "These are really exciting findings. We have been building a body of evidence over the past six years to show that singing in a choir can have a range of social, emotional and psychological benefits, and now we can see it has biological effects too.

"We've long heard anecdotal evidence that singing in a choir makes people feel good, but this is the first time it's been demonstrated that the immune system can be affected by singing. It's really exciting and could enhance the way we support people with cancer in the future."

The study also found that those with the lowest levels of mental wellbeing and highest levels of depression experienced greatest mood improvement, associated with lower levels of inflammation in the body. There is a link between high levels of inflammation and serious illness.

Choir members gave samples of their saliva before an hour of singing, and then again just after. The samples were analysed to see what changes occurred in a number of hormones, immune proteins, neuropeptides and receptors.

Dr Daisy Fancourt, Research Associate at the Centre for Performance Science, a partnership between the Royal College of Music and Imperial College London and co-author of the research, said: "Many people affected by cancer can experience psychological difficulties such as stress, anxiety and depression. Research has demonstrated that these can suppress immune activity, at a time when patients need as much support as they can get from their immune system. This research is exciting as it suggests that an activity as simple as singing could reduce some of this stress-induced suppression, helping to improve wellbeing and quality of life amongst patients and put them in the best position to receive treatment."

Diane Raybould, 64, took part in the study and has been singing with the Bridgend Sing with Us choir since 2010. Diane was diagnosed with breast cancer when she was aged 50. Her daughter was diagnosed with breast cancer at the same time and sadly, passed away from the disease at just 28. Diane said: "Singing in the choir is about more than just enjoyment, it genuinely makes you feel better. The choir leaders play a huge part of course, but so does the support of the other choir members, the inspirational programme and uplifting songs. The choir is a family, simple as that. Having cancer and losing someone to cancer can be very isolating. With the choir, you can share experiences openly and that is hugely important."

Rosie Dow, Head of Sing with Us at Tenovus Cancer Care and co-author of the research, added: "This research is so exciting, as it echoes everything all our choir members tell us about how singing has helped them. I've seen peoples' lives transformed through singing in our choirs so knowing that singing also makes a biological difference will hopefully help us to reach more people with the message that singing is great for you -- mind, body and soul."

Following on from this research, Tenovus Cancer Care is launching a two year study looking in more depth at the longitudinal effect of choir singing over several months. It will look at mental health, wellbeing, social support and ability to cope with cancer, alongside measuring stress hormones and immune function amongst patients, carers, staff and people who have lost somebody to cancer.
https://www.sciencedaily.com/releases/2016/04/160404221004.htm

Insomnia linked to damage in brain communication networks

April 5, 2016
Science Daily/Radiological Society of North America
Using a sophisticated MRI technique, researchers have found abnormalities in the brain's white matter tracts in patients with insomnia, according to a new study.
https://images.sciencedaily.com/2016/04/160405093052_1_540x360.jpg
Figure 1 shows the distribution of the six whole WM tracts in the brain. ALIC = anterior limb of the internal capsule, ACR = anterior corona radiata, BCC = body of the corpus callosum, PLIC = posterior limb of the internal capsule, R = right side of the brain, SCR = superior corona radiata, SLF = superior longitudinal fasciculus.
Credit: Radiological Society of North America

Primary insomnia, in which individuals have difficulty falling or staying asleep for a month or longer, is associated with daytime fatigue, mood disruption and cognitive impairment. Insomnia can also lead to depression and anxiety disorders.

"Insomnia is a remarkably prevalent disorder," said researcher Shumei Li, M.S., from the Department of Medical Imaging, Guangdong No. 2 Provincial People's Hospital, Guangzhou, China. "However, its causes and consequences remain elusive."

For the study, Li, along with colleagues lead by investigator Guihua Jiang, M.D., set out to analyze the white matter tracts in insomnia patients and the relationship between abnormal white matter integrity and the duration and features of insomnia.

"White matter tracts are bundles of axons--or long fibers of nerve cells--that connect one part of the brain to another," Li said. "If white matter tracts are impaired, communication between brain regions is disrupted."

The study included 23 patients with primary insomnia and 30 healthy control volunteers. To evaluate mental status and sleep patterns, all participants completed questionnaires including the Pittsburgh Sleep Quality Index, the Insomnia Severity Index, the Self-Rating Anxiety Scale and the Self-Rating Depression Scale.

Each participant also underwent brain MRI with a specialized technique called diffusion tensor imaging (DTI). DTI allows researchers to analyze the pattern of water movement along white matter tracts to identify a loss of tract integrity.

"We used a new method called Tract-Based Spatial Statistics that is highly sensitive to the microstructure of the white matter tract and provides multiple diffusion measures," Li said.

Results of the analysis showed that compared to the healthy controls, the insomnia patients had significantly reduced white matter integrity in several right-brain regions, and the thalamus which regulates consciousness, sleep and alertness.

"These impaired white matter tracts are mainly involved in the regulation of sleep and wakefulness, cognitive function and sensorimotor function," Li said.

In addition, abnormalities in the thalamus and body corpus callosum--the largest white matter structure in the brain--were associated with the duration of patients' insomnia and score on self-rating depression scale.

"The involvement of the thalamus in the pathology of insomnia is particularly critical, since the thalamus houses important constituents of the body's biological clock," she added.

The study also found that underlying cause of white matter integrity abnormalities in insomnia patients may be loss of myelin, the protective coating around nerve fibers.

The researchers caution that further study needs to be done on a larger sample to clarify the relationship between altered white matter integrity and insomnia.
https://www.sciencedaily.com/releases/2016/04/160405093052.htm

Fresh fruit associated with lower risk of heart attack and stroke Study of 500,000 Chinese adults confirms benefits of eating fruit

April 6, 2016
Science Daily/University of Oxford
People who eat fresh fruit on most days are at lower risk of heart attack and stroke than people who rarely eat fresh fruit, according to new research. The findings come from a seven-year study of half a million adults in China, where fresh fruit consumption is much lower than in countries like the UK or US.
https://images.sciencedaily.com/2016/04/160406181538_1_540x360.jpg
Fruit is a rich source of potassium, dietary fiber, antioxidants, and various other potentially active compounds, and contains little sodium or fat and relatively few calories.
Credit: © baibaz / Fotolia

Researchers from the University of Oxford and Chinese Academy of Medical Sciences conducted a large, nationwide study of 500,000 adults from 10 urban and rural localities across China, tracking health for 7 years through death records and electronic hospital records of illness. The present study was among people who did not have a history of cardiovascular diseases or anti-hypertensive treatments when first joined the study.

Fruit is a rich source of potassium, dietary fiber, antioxidants, and various other potentially active compounds, and contains little sodium or fat and relatively few calories. The study found that fruit consumption (which was mainly apples or oranges) was strongly associated with many other factors, such as education, lower blood pressure, lower blood glucose, and not smoking. But, after allowing for what was known of these and other factors, a 100g portion of fruit per day was associated with about one-third less cardiovascular mortality and the association was similar across different study areas and in both men and women.

Study author Dr Huaidong Du, University of Oxford, UK, said "The association between fruit consumption and cardiovascular risk seems to be stronger in China, where many still eat little fruit, than in high-income countries where daily consumption of fruit is more common." Also, fruit in China is almost exclusively consumed raw, whereas much of the fruit in high-income countries is processed, and many previous studies combined fresh and processed fruit.

Co-author Professor Liming Li, Chinese Academy of Medical Sciences, said "A recent Global Burden of Disease report put low fruit consumption as one of the leading causes of premature death in China. However, this was based on little evidence from China itself."

The senior author, Professor Zhengming Chen, University of Oxford, UK, said "It's difficult to know whether the lower risk in people who eat more fresh fruit is because of a real protective effect. If it is, then widespread consumption of fresh fruit in China could prevent about half a million cardiovascular deaths a year, including 200,000 before age 70, and even larger numbers of non-fatal strokes and heart attacks."
https://www.sciencedaily.com/releases/2016/04/160406181538.htm

How depression may compound risk of type 2 diabetes Depression, metabolic factors combine to boost risk of developing diabetes, study finds

April 12, 2016
Science Daily/McGill University
Depression may compound the risk of developing type 2 diabetes in people with such early warning signs of metabolic disease as obesity, high blood pressure and unhealthy cholesterol levels, according to researchers from McGill University, l'Université de Montréal, the Institut de recherches cliniques de Montréal and the University of Calgary.

While previous studies have pointed to a link between depression and diabetes, the new findings, published in the journal Molecular Psychiatry, suggest that when depression combines with metabolic risk factors the risk of developing diabetes rises to a level beyond the sum of its parts.

"Emerging evidence suggests that not depression, per se, but depression in combination with behavioral and metabolic risk factors increases the risk of developing type 2 diabetes and cardiovascular conditions," said lead author Norbert Schmitz, an Associate Professor in McGill's Department of Psychiatry and a researcher at its affiliated Douglas Mental Health University Institute. "The aim of our study was to evaluate characteristics of individuals with both depressive symptoms and metabolic risk factors."

Over 2,500 adults studied

The four-and-a-half year study divided 2,525 participants in Quebec, aged between 40 and 69, into four groups: those with both depression and three or more metabolic risk factors; two groups, each with one of these conditions but not the other; and a reference group with neither condition.

In a departure from previous findings, the researchers discovered that participants with depression, alone, were not at significantly greater risk of developing diabetes than those in the reference group. The group with metabolic symptoms but not depression was around four times more likely to develop diabetes. Those with both depression and metabolic risk factors, on the other hand, were more than six times more likely to develop diabetes, with the analysis showing the combined effect of depression and metabolic symptoms was greater than the sum of the individual effects.

A vicious cycle?

The researchers believe depression, metabolic symptoms and the risk of developing diabetes interact in a number of ways. In some cases, a vicious cycle may emerge with depression and metabolic risk factors aggravating one another.

Evidence shows people suffering from depression are less likely to adhere to medical advice aimed at tackling metabolic symptoms, whether it be taking medication, quitting smoking, getting more exercise or eating a healthier diet. Without effective management, metabolic symptoms often worsen and this can in turn exacerbate the symptoms of depression.

Beyond these behavioral aspects, some forms of depression are associated with changes in the body's metabolic systems which can lead to weight gain, high blood pressure and problems with glucose metabolism. Meanwhile, some antidepressant medications can also cause weight gain.

Integrated treatment key to prevention

The researchers emphasize that not all cases of depression are the same -- only some people with depression also suffer from metabolic problems. When it comes to improving health outcomes, identifying those patients who suffer from both depression and metabolic symptoms as a subgroup and adopting an integrated treatment approach may be crucial to breaking the cycle.

"Focussing on depression alone might not change lifestyle/metabolic factors, so people are still at an increased risk of developing poor health outcomes, which in turn increases the risk of developing recurrent depression," Prof. Schmitz said.
https://www.sciencedaily.com/releases/2016/04/160412211338.htm

New study illuminates key aspects of how we fall asleep and wake up Discovery could eventually lead to new and better treatments for insomnia and jet lag

April 14, 2016
Science Daily/University of Maryland School of Medicine
Falling asleep and waking up are key transitions in everyone's day. Despite decades of research, how these transitions work -- the neurobiological mechanics of our circadian rhythm -- has remained largely a mystery to brain scientists. Now, however, scientists have identified the workings of a key pathway for these processes. The pathway that appears to play a key role in regulating the 'switch' between wakefulness and sleep.
https://images.sciencedaily.com/2016/04/160414174410_1_540x360.jpg

Mice sleep during the day, when BK channels should be inhibited. This daytime BK channel inhibition results in high neuronal activity that leads to sleep. At night, BK channels become active, passing potassium (K+) current, and lowering neuronal activity. Lower neuronal activity triggers wakefulness, and activities such as wheel running. The link between neuronal activity and the sleep/wake cycles is similar in humans, with one key difference: humans tend to be daytime animals, awake in the day and asleep at night.
Credit: Andrea Meredith

Now, however, scientists at the University of Maryland School of Medicine (UM SOM) have identified the workings of a key pathway for these processes. The pathway that appears to play a key role in regulating the "switch" between wakefulness and sleep. This is the first study to elucidate this process in such biophysical detail.

Andrea Meredith, PhD, Associate Professor of Physiology at UM SOM, focused on a particular brain area, the suprachiasmatic nucleus in the hypothalamus. This region acts as the brain's internal clock, determining when we feel like going to sleep, how long we sleep, and when we feel like getting up. Within the suprachiasmatic nucleus, which is known as the SCN, she focused on certain ion channels, proteins that conduct electrical current, relaying information from one neuron to another. She focused on a group of channels known as BK potassium channels, which seem to be particularly active in the SCN.

In the paper, which appeared recently in Nature Communications, Dr. Meredith examined mice, whose schedule is opposite to humans -- they sleep during the day and are awake at night. She found that BK channels are active during waking, which for the mice was at night; during the day the BK channels were inactive. She found that in this daytime context, the role of the BK channels is to inhibit wakefulness.

Prof. Meredith examined normal mice, along with mice that had been genetically altered so that their BK channels could not be inactivated. She then recorded activity in these channels, via electrodes placed in SCN neurons. In the brains of the genetically modified group, the animals that could not inactivate their BK channels, she found lower levels of neuronal activity, which was associated with more daytime wakefulness. This was unusual, because mice generally sleep during the day.

The new findings are surprising, for several reasons. The researchers didn't know of any physiological process in the body that relied on BK channel inactivation as a mechanism. Scientists had known that the channel acted in this way, but didn't know how neurons used this mechanism to regulate information coding in the brain. This is the first study to show that BK channel inactivation is critical for encoding circadian rhythm in the brain.

Previously, BK channels had been known to be important for regulating other physiological functions. They are important for activating muscles, and play a prominent role in controlling blood pressure, heart rate, and bladder function. In the brain, BK channels have been known to be involved in regulating neuronal excitability, and play a role in motor control, learning and memory. In the brain, dysfunction in BK channels is associated with tremors, seizures, addiction, and problems with learning and memory.

"We knew that BK channels were widely important throughout the body," says Prof. Meredith. "But now we have strong evidence that they are specifically and intrinsically involved in the wake-sleep cycle. That's really exciting."

Also, in the past, scientists had thought that the day-night pattern of firing was largely driven by a different mechanism, the number of ion channels that exist on the surface of SCN neurons. The new paper showed that this model is too simplistic. The new study shows that the key is not the number of channels, but the fact that the channels are being activated, and more importantly, inactivated, at specific times of day.

The discovery has clinical implications. Prof. Meredith says the new understanding of the inactivation mechanism could potentially be used to develop drugs that target circadian rhythms. Such a medication could be used to treat sleep disorders, jet lag, and seasonal affective disorder, all of which involve problems with the SCN circadian clock.
https://www.sciencedaily.com/releases/2016/04/160414174410.htm

Finding sleep's sweet spot Study connects early bedtime and 'adequate' sleep with heart healthy choices

April 21, 2016
Science Daily/University of Delaware
A new study shows that when it comes to promoting healthy hearts, it's not a matter of getting more sleep. It's a matter of getting adequate sleep at optimal times, say researchers.

Night owls should take special note of a new study by University of Delaware researcher Freda Patterson and collaborators at the University of Pennsylvania, Drexel University and the University of Arizona College of Medicine, who found that the early-to-bed, early-to-rise approach aligns much better with cardiovascular health.

Sleep deficits and poor-quality sleep have been linked to obesity and a myriad of health problems, but this study shows that when it comes to promoting healthy hearts, it's not a matter of getting more sleep. It's a matter of getting adequate sleep at optimal times.

Doing that seems to reduce the kind of behaviors -- smoking, sedentary lifestyles and poor dietary choices -- that put hearts in harm's way.

"There are some who believe that sleep as a physiological function is upstream to these heart-health behaviors," said Patterson, assistant professor of behavioral health and nutrition in the University's College of Health Sciences. "If that is true, the implication would be that if we can modify sleep as a central risk factor, we might be in much better position to leverage or modify some of our most stubborn cardiovascular risk behaviors such as tobacco use."

The study, published in the Annals of Behavioral Medicine, examined the duration and approximate timing of sleep to see what patterns might be linked to the three prime suspects of cardiovascular trouble -- smoking, poor diet and sedentary habits. Those three behaviors have been blamed for about 40 percent of cardiovascular deaths in the United States and the United Kingdom.

The study had an enormous pool of data with which to work, drawing from the United Kingdom's Biobank Resource and a sample of 439,933 adults, between the ages of 40-69.

They found several strong connections, but first, a few notes about definitions and methods.

The study defined short sleep as less than six hours, adequate sleep as seven to eight hours, and long sleep as nine hours or more. Respondents were categorized by their self-reported sleep-timing or "chronotype" -- whether they considered themselves a morning person, more morning than evening, more evening than morning, or an evening person.

Participants were asked about their physical activity, how much time they spent using a computer or watching TV on an average day, how many servings of fruits and vegetables they had each day and how many cigarettes they typically smoked in an average day.

And the bottom line was this -- those whose sleep was either short or long and the night owls who went to bed later were more likely than adequate sleepers and those who went to bed earlier to smoke, remain sedentary and eat fewer fruits and vegetables.

"These data suggest that it's not just sleep deprivation that relates to cardiovascular risk behaviors, but too much sleep can relate as well," Patterson said. "Oftentimes, health messages say we need to get more sleep, but this may be too simplistic. Going to bed earlier and getting adequate sleep was associated with better heart health behaviors."

The American Health Association reports that only 5-10 percent of adults meet ideal standards in diet, physical activity and tobacco use. The rest of us have work to do.

"We know that people who are active tend to have better sleep patterns, and we also know that people who do not get their sleep are less likely to be active," Patterson said. "A pressing question for practitioners and researchers is how do you leverage one to improve the other?"

Data on the population studied were derived from the United Kingdom Biobank Resource, which draws on the UK's national health service. Subjects were between 40-69 years old during the four-year data collection period, which went from 2006-10.

Despite the enormous sample size, the data had some limitations, Patterson said. Population diversity was limited, for example. Ninety-five percent of respondents were white. And the data were largely based on self-report.

Further study is required to determine whether promoting adequate sleep and earlier-to-bed patterns would improve heart health.

http://www.sciencedaily.com/releases/2014/11/141103121020.htm