Fetal Exposure to Excessive Stress Hormones Linked to Adult Mood Disorders
Apr. 6, 2013 —
Science Daily/British Neuroscience Association
Exposure of the developing fetus to excessive levels of stress hormones in the womb can cause mood disorders in later life and now, for the first time, researchers have found a mechanism that may underpin this process, according to research presented April 7 at the British Neuroscience Association Festival of Neuroscience (BNA2013) in London.
Adverse environments experienced while in the womb, such as in cases of stress, bereavement or abuse, will increase levels of glucocorticoids in the mother, which may harm the growing baby. Glucocorticoids are naturally produced hormones and they are also known as stress hormones because of their role in the stress response.
"The stress hormone cortisol may be a key factor in programming the fetus, baby or child to be at risk of disease in later life. Cortisol causes reduced growth and modifies the timing of tissue development as well as having long lasting effects on gene expression," she will say.
Puberty is another sensitive time of development and stress experienced at this time can also be involved in programming adult mood disorders. Prof Holmes and her colleagues have found evidence from imaging studies in rats that stress in early teenage years could affect mood and emotional behaviour via changes in the brain's neural networks associated with emotional processing.
Prof Holmes will say: "We showed that in stressed 'teenage' rats, the part of the brain region involved in emotion and fear (known as amygdala) was activated in an exaggerated fashion when compared to controls. The results from this study clearly showed that altered emotional processing occurs in the amygdala in response to stress during this crucial period of development."
http://www.sciencedaily.com/releases/2013/04/130407090835.htm
Brain's Stress Circuits Undergo Profound Learning Early in Life
Apr. 7, 2013 —
Science Daily/University of California – Berkeley
https://www.sciencedaily.com/images/2013/04/130416204546_1_540x360.jpg
Brain cells called astrocytes (pink) appear to be key players in the response to acute stress. Stress hormones stimulate astrocytes to release fibroblast growth factor 2 (green), which in turn lead to new neurons (blue).
Credit: Image by Daniela Kaufer & Liz Kirby
Overworked and stressed out? Look on the bright side. Some stress is good for you.
"You always think about stress as a really bad thing, but it's not," said Daniela Kaufer, associate professor of integrative biology at the University of California, Berkeley. "Some amounts of stress are good to push you just to the level of optimal alertness, behavioral and cognitive performance."
New research by Kaufer and UC Berkeley post-doctoral fellow Elizabeth Kirby has uncovered exactly how acute stress -- short-lived, not chronic -- primes the brain for improved performance.
In studies on rats, they found that significant, but brief stressful events caused stem cells in their brains to proliferate into new nerve cells that, when mature two weeks later, improved the rats' mental performance.
"I think intermittent stressful events are probably what keeps the brain more alert, and you perform better when you are alert," she said.
Kaufer, Kirby and their colleagues in UC Berkeley's Helen Wills Neuroscience Institute describe their results in a paper published April 16 in the new open access online journal eLife.
The UC Berkeley researchers' findings, "in general, reinforce the notion that stress hormones help an animal adapt -- after all, remembering the place where something stressful happened is beneficial to deal with future situations in the same place," said Bruce McEwen, head of the Harold and Margaret Milliken Hatch Laboratory of Neuroendocrinology at The Rockefeller University, who was not involved in the study.
Kaufer is especially interested in how both acute and chronic stress affect memory, and since the brain's hippocampus is critical to memory, she and her colleagues focused on the effects of stress on neural stem cells in the hippocampus of the adult rat brain. Neural stem cells are a sort of generic or progenitor brain cell that, depending on chemical triggers, can mature into neurons, astrocytes or other cells in the brain. The dentate gyrus of the hippocampus is one of only two areas in the brain that generate new brain cells in adults, and is highly sensitive to glucocorticoid stress hormones, Kaufer said.
Much research has demonstrated that chronic stress elevates levels of glucocorticoid stress hormones, which suppresses the production of new neurons in the hippocampus, impairing memory. This is in addition to the effect that chronically elevated levels of stress hormones have on the entire body, such as increasing the risk of chronic obesity, heart disease and depression.
Less is known about the effects of acute stress, Kaufer said, and studies have been conflicting.
To clear up the confusion, Kirby subjected rats to what, to them, is acute but short-lived stress -- immobilization in their cages for a few hours. This led to stress hormone (corticosterone) levels as high as those from chronic stress, though for only a few hours. The stress doubled the proliferation of new brain cells in the hippocampus, specifically in the dorsal dentate gyrus.
Kirby discovered that the stressed rats performed better on a memory test two weeks after the stressful event, but not two days after the event. Using special cell labeling techniques, the researchers established that the new nerve cells triggered by the acute stress were the same ones involved in learning new tasks two weeks later.
"In terms of survival, the nerve cell proliferation doesn't help you immediately after the stress, because it takes time for the cells to become mature, functioning neurons," Kaufer said. "But in the natural environment, where acute stress happens on a regular basis, it will keep the animal more alert, more attuned to the environment and to what actually is a threat or not a threat."
They also found that nerve cell proliferation after acute stress was triggered by the release of a protein, fibroblast growth factor 2 (FGF2), by astrocytes -- brain cells formerly thought of as support cells, but that now appear to play a more critical role in regulating neurons.
"The FGF2 involvement is interesting, because FGF2 deficiency is associated with depressive-like behaviors in animals and is linked to depression in humans," McEwen said.
Kaufer noted that exposure to acute, intense stress can sometimes be harmful, leading, for example, to post-traumatic stress disorder. Further research could help to identify the factors that determine whether a response to stress is good or bad.
"I think the ultimate message is an optimistic one," she concluded. "Stress can be something that makes you better, but it is a question of how much, how long and how you interpret or perceive it."
The eLife paper was coauthored by UC Berkeley colleagues Sandra E Muroy, Wayne G. Sun and David Covarrubias of the Department of Molecular and Cell Biology; Megan J. Leong of the Helen Wills Neuroscience Institute; and Laurel A. Barchas of the Department of Integrative Biology. Kirby is now a post-doctoral fellow at Stanford University.
Kaufer's research was funded by a BRAINS (Biobehavioral Research Awards for Innovative New Scientists) award from the National Institute of Mental Health of the National Institutes of Health (R01 MH087495) and the National Alliance for Research on Schizophrenia and Depression. Kirby was supported by fellowships from the California Institute for Regenerative Medicine and the U.S. Department of Defense.
http://www.sciencedaily.com/releases/2013/04/130407133314.htm
Acute Stress Primes Brain for Better Cognitive and Mental Performance
Apr. 16, 2013 —
Science Daily/University of California - Berkeley
https://www.sciencedaily.com/images/2013/04/130416204546_1_540x360.jpg
Brain cells called astrocytes (pink) appear to be key players in the response to acute stress. Stress hormones stimulate astrocytes to release fibroblast growth factor 2 (green), which in turn lead to new neurons (blue).
Credit: Image by Daniela Kaufer & Liz Kirby
Overworked and stressed out? Look on the bright side. Some stress is good for you. "You always think about stress as a really bad thing, but it's not," said Daniela Kaufer, associate professor of integrative biology at the University of California, Berkeley. "Some amounts of stress are good to push you just to the level of optimal alertness, behavioral and cognitive performance."
New research by Kaufer and UC Berkeley post-doctoral fellow Elizabeth Kirby has uncovered exactly how acute stress -- short-lived, not chronic -- primes the brain for improved performance.
Kaufer noted that exposure to acute, intense stress can sometimes be harmful, leading, for example, to post-traumatic stress disorder. Further research could help to identify the factors that determine whether a response to stress is good or bad. "I think the ultimate message is an optimistic one," she concluded. "Stress can be something that makes you better, but it is a question of how much, how long and how you interpret or perceive it."
http://www.sciencedaily.com/releases/2013/04/130416204546.htm
Social Stress and the Inflamed Brain
Apr. 21, 2013 —
Science Daily/Federation of American Societies for Experimental Biology
Depression is the leading cause of disability with more than 350 million people globally affected by this disease. In addition to debilitating consequences on mental health, depression predisposes an individual to physiological disease such as heart disease, and conversely heart disease increases the risk of depression.
According to the World Health Organization by the year 2020 heart disease and depression will be the number one and number two leading causes of disability in developed countries. While the co-occurrence of these disorders is well recognized, an understanding of the underlying mechanisms that lead to this relationship are lacking.
The identification of factors in the brain that distinguish susceptibility and resiliency to depression and heart disease comorbidity would be a major advance in predicting, preventing and treating these disorders. Dr. Wood is continuing these studies as an Assistant Professor at the University of South Carolina School of Medicine with the hope that these findings will uncover new targets to treat the mind and body.
http://www.sciencedaily.com/releases/2013/04/130421153839.htm
Cutting Back On Sleep Harms Blood Vessel Function and Breathing Control
Apr. 22, 2013 —
Science Daily/American Physiological Society (APS)
With work and entertainment operating around the clock in our modern society, sleep is often a casualty. A bevy of research has shown a link between sleep deprivation and cardiovascular disease, metabolic disorders, and obesity. However, it's been unclear why sleep loss might lead to these effects. Several studies have tested the effects of total sleep deprivation, but this model isn't a good fit for the way most people lose sleep, with a few hours here and there. In a new study by Keith Pugh, Shahrad Taheri, and George Balanos, all of the University of Birmingham in the United Kingdom, researchers test the effects of partial sleep deprivation on blood vessels and breathing control. They find that reducing sleep length over two consecutive nights leads to less healthy vascular function and impaired breathing control.
Cutting Sleep in Half The researchers have worked with eight healthy adult volunteers between the ages of 20 to 35 to date. For the first two nights of the study, the researchers had these volunteers sleep a normal night of eight hours. Then, rather than restrict their sleep completely, the researchers instead had them sleep only four hours during each of three consecutive nights.
Each of these volunteers underwent tests to see how well their blood vessels accommodate an increase in blood flow, a test of healthy blood vessel, or vascular, function. Following the first two nights of restricted sleep, the researchers found a significant reduction in vascular function compared to following the nights of normal sleep. However, after the third night of sleep restriction, vascular function returned to baseline, possibly an adaptive response to acute sleep loss, study leader Pugh explains.
In other tests, the researchers exposed subjects to moderately high levels of carbon dioxide, which normally increases the depth and rate of breathing. However, breathing control was substantially reduced after the volunteers lost sleep.
The researchers later had these volunteers sleep 10 hours a night for five nights. After completing the same tests, results showed that vascular function and breathing control had improved.
A Mechanism for Cardiovascular Harm Pugh notes that the results could suggest a mechanism behind the connection between sleep loss and cardiovascular disease. "If acute sleep loss occurs repetitively over a long period of time, then vascular health could be compromised further and eventually mediate the development of cardiovascular disease," he explains.
Similarly, the loss of breathing control that the researchers observed could play a role in the development of sleep apnea, which has also been linked with cardiovascular disease. Pugh adds that some populations who tend to report sleeping shorter periods, such as the elderly, could be at an even higher risk of these adverse health effects.
He and his colleagues plan to continue studying these effects in more subjects to strengthen their results. Eventually, Pugh says, they hope to discover a mechanism to explain why restricting sleep harms vascular function and breathing control.
http://www.sciencedaily.com/releases/2013/04/130422102026.htm
Getting a Grip On Sleep
May 14, 2013 —
Science Daily/RIKEN
All mammals sleep, as do birds and some insects. However, how this basic function is regulated by the brain remains unclear. According to a new study by researchers from the RIKEN Brain Science Institute, a brain region called the lateral habenula plays a central role in the regulation of REM sleep. In an article published today in the Journal of Neuroscience, the team shows that the lateral habenula maintains and regulates REM sleep in rats through regulation of the serotonin system.
“Our results indicate that the lateral habenula is essential for maintaining theta rhythms in the hippocampus, which characterize REM sleep in the rat, and that this is done via serotonergic modulation,” concludes Dr Aizawa. “This study reveals a novel role of the lateral habenula, linking serotonin and REM sleep, which suggests that an hyperactive habenula in patients with depression may cause altered REM sleep,” add the authors.
http://www.sciencedaily.com/releases/2013/05/130514184514.htm
Light Therapy Improves Sleep and Promote Recovery in Patients With Mild TBI
May 31, 2013 —
Science Daily/American Academy of Sleep Medicine
A new study suggests that bright light therapy may improve sleep, cognition, emotion and brain function following mild traumatic brain injury (TBI).
Results show that six weeks of morning bright light therapy resulted in a marked decrease in subjective daytime sleepiness. This improvement was further associated with improvements in the propensity to fall asleep and nighttime sleep quality. Bright light therapy also affected depressive symptoms.
"Our preliminary data suggests that morning bright light therapy might be helpful to reduce subjective daytime sleepiness and to improve nighttime sleep," said investigator Mareen Weber, PhD, instructor in psychiatry at McLean Hospital/Harvard Medical School in Belmont, Mass. "Importantly, the research also shows changes in brain activation during a demanding cognitive task, suggesting that bright light treatment might yield changes in brain functioning."
The research abstract was published recently in an online supplement of the journal SLEEP, and Weber will present the findings Monday, June 3, in Baltimore, Md., at SLEEP 2013, the 27th annual meeting of the Associated Professional Sleep Societies LLC.
The study group comprised 18 individuals with a documented history of at least one mild TBI and sleep disturbance that either emerged or was aggravated with the most recent injury. Data were gathered using Multiple Sleep Latency Tests (MSLT), actigraphy and sleep diaries, and all participants underwent magnetic resonance imaging (MRI) and comprehensive psychiatric and neuropsychological assessments before and after the intervention.
According to the authors, it has been estimated that at least 50 percent of individuals with TBI experience some kind of sleep disturbance at some point following their injury, and sleep has been demonstrated to be essential for brain plasticity and may be important for recovery.
"Improving sleep following mild traumatic brain injury could prove critical to maximizing recovery from the injury," said Weber. "Furthermore, bright light therapy is easy and minimally invasive, requiring no medication, and has no known serious side effects."
http://www.sciencedaily.com/releases/2013/05/130531105518.htm
Blood Vessels in the Eye Linked With IQ, Cognitive Function
June 3, 2013 —
Science Daily/Association for Psychological Science
https://www.sciencedaily.com/images/2013/06/130603135533_1_540x360.jpg
Eye exam. The width of blood vessels in the retina, located at the back of the eye, may indicate brain health years before the onset of dementia and other deficits.
Credit: © lightpoet / Fotolia
The width of blood vessels in the retina, located at the back of the eye, may indicate brain health years before the onset of dementia and other deficits, according to a new study published in Psychological Science, a journal of the Association for Psychological Science.
Research shows that younger people who score low on intelligence tests, such as IQ, tend to be at higher risk for poorer health and shorter lifespan, but factors like socioeconomic status and health behaviors don't fully account for the relationship.
The findings suggest that the processes linking vascular health and cognitive functioning begin much earlier than previously assumed, years before the onset of dementia and other age-related declines in brain functioning.
"Digital retinal imaging is a tool that is being used today mainly by eye doctors to study diseases of the eye," Shalev notes. "But our initial findings indicate that it may be a useful investigative tool for psychological scientists who want to study the link between intelligence and health across the lifespan."
http://www.sciencedaily.com/releases/2013/06/130603135533.htm
Are Smartphones Disrupting Your Sleep?
June 3, 2013 —
Science Daily/Mayo Clinic
Smartphones and tablets can make for sleep-disrupting bedfellows. One cause is believed to be the bright light-emitting diodes that allow the use of mobile devices in dimly lit rooms; the light exposure can interfere with melatonin, a hormone that helps control the natural sleep-wake cycle. But there may be a way to check your mobile device in bed and still get a good night's sleep. A Mayo Clinic study suggests dimming the smartphone or tablet brightness settings and holding the device at least 14 inches from your face while using it will reduce its potential to interfere with melatonin and impede sleep.
"There's a lot of concern about using mobile devices and that prompted me to wonder, are they always a negative factor for sleep?" Dr. Krahn says. "We found that only at the highest setting was the light over a conservative threshold that might affect melatonin levels. If it's at the mid setting or at a low setting it's bright enough to use."
http://www.sciencedaily.com/releases/2013/06/130603163610.htm
Getting Enough Sleep Could Help Prevent Type 2 Diabetes
June 18, 2013 —
Science Daily/Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center (LA BioMed)
Men who lose sleep during the work week may be able to lower their risk of developing Type 2 diabetes by getting more hours of sleep, according to Los Angeles Biomedical Research Institute (LA BioMed) research findings presented today at The Endocrine Society's 95th Annual Meeting in San Francisco.
"We all know we need to get adequate sleep, but that is often impossible because of work demands and busy lifestyles," said Dr. Liu. "Our study found extending the hours of sleep can improve the body's use of insulin, thereby reducing the risk of Type 2 diabetes in adult men. Reducing the incidence of this chronic illness is critical for a nation where diabetes affects nearly 26 million people and costs an estimated $174 billion annually."
"The good news is that by extending the hours they sleep, adult men -- who over a long period of time do not get enough sleep during the working week -- can still improve their insulin sensitivity," Liu said
http://www.sciencedaily.com/releases/2013/06/130618131848.htm
Stress Hormone Could Trigger Mechanism for the Onset of Alzheimer's
June 19, 2013 —
Science Daily/Temple University
A chemical hormone released in the body as a reaction to stress could be a key trigger of the mechanism for the late onset of Alzheimer's disease, according to a study by researchers at Temple University.
"Stress is an environmental factor that looks like it may play a very important role in the onset of Alzheimer's disease," said Domenico Praticò, professor of pharmacology and microbiology and immunology in Temple's School of Medicine, who led the study. "When the levels of corticosteroid are too high for too long, they can damage or cause the death of neuronal cells, which are very important for learning and memory."
http://www.sciencedaily.com/releases/2013/06/130619102605.htm
Helping SAD Sufferers Sleep Soundly
June 27, 2013 —
Science Daily/University of Pittsburgh
Lying awake in bed plagues everyone occasionally, but for those with seasonal affective disorder, sleeplessness is routine. University of Pittsburgh researchers report in the Journal of Affective Disorders that individuals with seasonal affective disorder (SAD) -- a winter depression that leads to loss of motivation and interest in daily activities -- have misconceptions about their sleep habits similar to those of insomniacs. These findings open the door for treating seasonal affective disorder similar to the way doctors treat insomnia.
http://www.sciencedaily.com/releases/2013/06/130627142547.htm
Early Brain Stimulation May Help Stroke Survivors Recover Language Function
June 27, 2013 —
Science Daily/American Heart Association
Non-invasive brain stimulation may help stroke survivors recover speech and language function, according to new research in the American Heart Association journal Stroke.
"For decades, skilled speech and language therapy has been the only therapeutic option for stroke survivors with aphasia," said Alexander Thiel, M.D., study lead author and associate professor of neurology and neurosurgery at McGill University in Montreal, Quebec, Canada. "We are entering exciting times where we might be able in the near future to combine speech and language therapy with non-invasive brain stimulation earlier in the recovery. This could result in earlier and more efficient aphasia recovery and also have an economic impact."
In the small study, researchers treated 24 stroke survivors with several types of aphasia at the rehabilitation hospital Rehanova and the Max-Planck-Institute for neurological research in Cologne, Germany. Thirteen received transcranial magnetic stimulation (TMS) and 11 got sham stimulation. The TMS groups' improvements were on average three times greater than the non-TMS group, researchers said. They used German language aphasia tests, which are similar to those in the United States, to measure language performance of the patients.
"TMS had the biggest impact on improvement in anomia, the inability to name objects, which is one of the most debilitating aphasia symptoms," Thiel said.
http://www.sciencedaily.com/releases/2013/06/130627161434.htm
A Good Night's Sleep Increases the Cardiovascular Benefits of a Healthy Lifestyle
July 3, 2013
Science Daily/European Society of Cardiology (ESC)
A good night's sleep can increase the benefit of exercise, healthy diet, moderate alcohol consumption and non-smoking in their protection against cardiovascular disease (CVD), according to results of a large population follow-up study.(1) Results showed that the combination of the four traditional healthy lifestyle habits was associated with a 57% lower risk of cardiovascular disease (fatal and non-fatal) and a 67% lower risk of fatal events.(2) But, when "sufficient sleep" (defined as seven or more hours a night) was added to the other four lifestyle factors, the overall protective benefit was even further increased -- and resulted in a 65% lower risk of composite CVD and a 83% lower risk of fatal events.
As an explanation for the results, the investigators note that short sleep duration has been associated with a higher incidence of overweight, obesity and hypertension and with higher levels of blood pressure, total cholesterol, haemoglobin A, and triglycerides, effects which are "consistent with the hypothesis that short sleep duration is directly associated with CVD risk."
http://www.sciencedaily.com/releases/2013/07/130702202825.htm
Bad Night's Sleep? The Moon Could Be to Blame
July 25, 2013 —
Science Daily/Cell Press
https://www.sciencedaily.com/images/2013/07/130725125303_1_540x360.jpg
Many people complain about poor sleep around the full moon, and now a report appearing in Current Biology, a Cell Press publication, on July 25 offers some of the first convincing scientific evidence to suggest that this really is true. The findings add to evidence that humans -- despite the comforts of our civilized world -- still respond to the geophysical rhythms of the moon, driven by a circalunar clock.
Credit: Current Biology, Cajochen et al.
Many people complain about poor sleep around the full moon, and now a report appearing in Current Biology, a Cell Press publication, on July 25 offers some of the first convincing scientific evidence to suggest that this really is true. The findings add to evidence that humans -- despite the comforts of our civilized world -- still respond to the geophysical rhythms of the moon, driven by a circalunar clock.
The data show that around the full moon, brain activity related to deep sleep dropped by 30 percent. People also took five minutes longer to fall asleep, and they slept for twenty minutes less time overall. Study participants felt as though their sleep was poorer when the moon was full, and they showed diminished levels of melatonin, a hormone known to regulate sleep and wake cycles.
"This is the first reliable evidence that a lunar rhythm can modulate sleep structure in humans when measured under the highly controlled conditions of a circadian laboratory study protocol without time cues," the researchers say.
"In nearly every measure we had, hamsters exposed to blue light were the worst off, followed by those exposed to white light," he said. "While total darkness was best, red light was not nearly as bad as the other wavelengths we studied."
http://www.sciencedaily.com/releases/2013/07/130725125303.htm
What color is your night light? It may affect your mood
August 6, 2013
Science Daily/Ohio State University
When it comes to some of the health hazards of light at night, a new study in hamsters suggests that the color of the light can make a big difference.
In a study involving hamsters, researchers found that blue light had the worst effects on mood-related measures, followed closely by white light.
But hamsters exposed to red light at night had significantly less evidence of depressive-like symptoms and changes in the brain linked to depression, compared to those that experienced blue or white light. The only hamsters that fared better than those exposed to red light were those that had total darkness at night.
The findings may have important implications for humans, particularly those whose work on night shifts makes them susceptible to mood disorders, said Randy Nelson, co-author of the study and professor of neuroscience and psychology at The Ohio State University.
"Our findings suggest that if we could use red light when appropriate for night-shift workers, it may not have some of the negative effects on their health that white light does," Nelson said.
http://www.sciencedaily.com/releases/2013/08/130806203150.htm
Light drinking linked to lower risk of depression
August 29, 2013
Science Daily/BioMed Central Limited
Drinking wine in moderation may be associated with a lower risk of developing depression, according to new research. The reported findings suggest that the moderate amounts of alcohol consumed may have similar protective effects on depression to those that have been observed for coronary heart disease. The lowest rates of depression were seen in the group of individuals who drank two to seven small glasses of wine per week.
The main alcoholic beverage drunk by the study participants was wine. When analysed, it was shown that those who drank moderate amounts of wine each week were less likely to suffer from depression. The lowest rates of depression were seen in the group of individuals who drank two to seven small glasses of wine per week. These results remained significant even when the group adjusted them for lifestyle and social factors, such as smoking, diet and marital status.
http://www.sciencedaily.com/releases/2013/08/130829214354.htm
Even mild stress can make it difficult to control your emotions
August 26, 2013
Science Daily/New York University
Even mild stress can thwart therapeutic measures to control emotions, a team of neuroscientists has found. Their findings point to the limits of clinical techniques while also shedding new light on the barriers that must be overcome in addressing afflictions such as fear or anxiety.
"The use of cognitive techniques to control fear has previously been shown to rely on regions of the prefrontal cortex that are known to be functionally impaired by mild stress," Phelps observed. "These findings are consistent with the suggestion that the effect of mild stress on the prefrontal cortex may result in a diminished ability to use previously learned techniques to control fear."
"Our results suggest that even mild stress, such as that encountered in daily life, may impair the ability to use cognitive techniques known to control fear and anxiety," added Candace Raio, a doctoral student in NYU's Department of Psychology and the study's lead author. "However, with practice or after longer intervals of cognitive training, these strategies may become more habitual and less sensitive to the effects of stress."
http://www.sciencedaily.com/releases/2013/08/130826180520.htm
Winter depression not as common as many think
August 27, 2013
Science Daily/Oregon State University
New research suggests that getting depressed when it's cold and dreary outside may not be as common as is often believed.
"We found a very small effect during the winter months, but it was much more modest than would be expected if seasonal depression were as common as many people think it is," said Columbia University researcher Jeff Shaman, a study co-author and a former OSU faculty member. "We were surprised. With a sample of nearly 800 people and very precise measures of the weather, we expected to see a larger effect."
Kerr believes the public may have overestimated the power of the winter blues for a few reasons. These may include awareness of SAD, the high prevalence of depression in general, and a legitimate dislike of winter weather.
"We may not have as much fun, we can feel cooped up and we may be less active in the winter," Kerr said. "But that's not the same as long-lasting sadness, hopelessness, and problems with appetite and sleep -- real signs of a clinical depression."
http://www.sciencedaily.com/releases/2013/08/130827135034.htm
Sleeping in on weekends doesn’t fix all deficits caused by workweek sleep loss
October 9, 2013
Science Daily/American Physiological Society (APS)
A new study assesses the effects of extended “weekend” recovery sleep following “one workweek” of mild sleep restriction on sleepiness/alertness, inflammation and stress hormones.
Not surprisingly, the researchers found that after 5 days of restricted sleep, the subjects were significantly sleepier on both objective and subjective tests compared to baseline levels. Their interleukin-6 levels increased sharply during restricted sleep, though their cortisol levels remained the same. Their performance on the attention test deteriorated. After 2 days of recovery sleep, both objective and subjective tests showed that the volunteers were less sleepy. Their interleukin-6 levels reduced, and their cortisol levels decreased significantly compared to baseline, possibly suggesting that the volunteers were sleep deprived before the study started. Notably, their performance on the attention test didn't improve after recovery sleep.
Though many indicators of health and well being improved after recovery sleep, these findings suggest that extra sleep may not fix all the deficits caused by lost sleep during the workweek.
"Two nights of extended recovery sleep may not be sufficient to overcome behavioral alertness deficits resulting from mild sleep restriction," the authors write. "This may have important implications for people with safety-critical professions, such as health-care workers, as well as transportation system employees (drivers, pilots, etc.)."
http://www.sciencedaily.com/releases/2013/10/131009125740.htm