How much sleep do we really need?
February 11, 2015
Science Daily/Loyola University Health System
An expert panel that examined data from 320 studies is recommending new guidelines on how much sleep people should get. The guidelines are based on age, ranging from newborns (who need 14 to 17 hours of sleep per day) to adults aged 65 and up (7 to 8 hours per day).
In the new guidelines, there's a wider range of what constitutes a good night's sleep. For example, the expert panel recommends that teens (ages 14 to 17) get 8 to 10 hours of sleep per night. The previous guideline had a narrower recommended range of 8.5 to 9.5 hours per night.
Dr. DonCarlos and other experts on the multidisciplinary panel examined findings from 320 studies reporting sleep duration findings for healthy individuals, effects of reduced or prolonged sleep duration and health consequences of too much or too little sleep. Results are published in Sleep Health: Journal of the National Sleep Foundation.
"The process was very rigorous," Dr. DonCarlos said. Dr. DonCarlos is a professor in the Department of Cell and Molecular Physiology of Loyola University Chicago Stritch School of Medicine.
The expert panel consists of 12 representatives, including Dr. DonCarlos, who were selected by medical organizations; and six sleep experts selected by the National Sleep Foundation. Dr. DonCarlos represents the American Association of Anatomists.
Dr. DonCarlos is a neuroendocrinologist who studies how hormones affect the structure of the brain. The section of the brain responsible for regulating hormone production is the hypothalamus. Hormones produced by the hypothalamus govern body temperature, hunger, stress responses, sex drive, circadian rhythms and sleep.
In addition to serving on the National Sleep Foundation expert panel, Dr. DonCarlos serves on the National Institutes of Health's Neuroendocrinology, Neuroimmunology, Rhythms and Sleep (NNRS) study section, which reviews applications for research grants.
"We still have a great deal to learn about the function of sleep," Dr. DonCarlos said. "We know it's restorative and important for memory consolidation. But we don't know the details of what the function of sleep is, even though it is how we spend one-third of our lives."
These are the sleep-time recommendations from the National Sleep Foundation expert panel:
Newborns (0-3 months): Sleep range narrowed to 14-17 hours each day (previously it was 12-18).
Infants (4-11 months): Sleep range widened two hours to 12-15 hours (previously it was 14-15).
Toddlers (1-2 years): Sleep range widened by one hour to 11-14 hours (previously it was 12-14).
Preschoolers (3-5): Sleep range widened by one hour to 10-13 hours (previously it was 11-13).
School age children (6-13): Sleep range widened by one hour to 9-11 hours (previously it was 10-11).
Teenagers (14-17): Sleep range widened by one hour to 8-10 hours (previously it was 8.5-9.5).
Younger adults (18-25): Sleep range is 7-9 hours (new age category).
Adults (26-64): Sleep range did not change and remains 7-9 hours.
Older adults (65+): Sleep range is 7-8 hours (new age category).
http://www.sciencedaily.com/releases/2015/02/150211132111.htm
Link between sleep loss, diabetes explained
February 19, 2015
Science Daily/University of Chicago Medical Center
http://images.sciencedaily.com/2015/02/150219084912-large.jpg
Lack of sleep can elevate levels of free fatty acids in the blood, accompanied by temporary pre-diabetic conditions in healthy young men. Getting enough sleep could help counteract the current epidemics of diabetes and obesity, scientists say.
The study, the first to examine the impact of sleep loss on 24-hour fatty acid levels in the blood, adds to emerging evidence that insufficient sleep -- a highly prevalent condition in modern society -- may disrupt fat metabolism and reduce the ability of insulin to regulate blood sugars. It suggests that something as simple as getting enough sleep could help counteract the current epidemics of diabetes and obesity.
"At the population level, multiple studies have reported connections between restricted sleep, weight gain, and type 2 diabetes," said Esra Tasali, MD, assistant professor of medicine at the University of Chicago and senior author of the study. "Experimental laboratory studies, like ours, help us unravel the mechanisms that may be responsible."
The researchers found that after three nights of getting only four hours of sleep, blood levels of fatty acids, which usually peak and then recede overnight, remained elevated from about 4 a.m. to 9 a.m. As long as fatty acid levels remained high, the ability of insulin to regulate blood sugars was reduced.
The results provide new insights into the connections, first described by University of Chicago researchers 15 years ago, between sleep loss, insulin resistance and heightened risk of type 2 diabetes.
The researchers recruited 19 healthy male subjects between the ages of 18 and 30. These volunteers were monitored through two scenarios in randomized order. In one, they got a full night's rest -- 8.5 hours in bed (averaging 7.8 hours asleep) during four consecutive nights. In the other, they spent just 4.5 hours in bed (averaging 4.3 hours asleep) for four consecutive nights. The two studies were spaced at least four weeks apart.
Each subject's sleep was carefully monitored, diet was strictly controlled and blood samples were collected at 15 or 30 minute intervals for 24 hours, starting on the evening of the third night of each study. The researchers measured blood levels of free fatty acids and growth hormone, glucose and insulin, and the stress hormones noradrenaline and cortisol. After four nights in each sleep condition, an intravenous glucose-tolerance test was performed.
They found that sleep restriction resulted in a 15 to 30 percent increase in late night and early morning fatty acid levels. The nocturnal elevation of fatty acids (from about 4 a.m. to 6 a.m.) correlated with an increase in insulin resistance -- a hallmark of pre-diabetes -- that persisted for a nearly five hours.
Cutting back on sleep prolonged nighttime growth hormone secretion and led to an increase in noradrenaline in the blood, both of which contributed to the increase in fatty acid levels.
Although glucose levels were unchanged, the ability of available insulin to regulate blood glucose levels decreased by about 23 percent after a short sleep, "suggesting," the authors note, "an insulin-resistant state."
"It definitely looks like a packaged deal," said the study's lead author, Josiane Broussard, PhD, a former graduate student at the University of Chicago who is now a post-doctoral research scientist at Cedars-Sinai Medical Center's Diabetes and Obesity Research Institute in Los Angeles.
"Curtailed sleep produced marked changes in the secretion of growth hormone and levels of noradrenaline -- which can increase circulating fatty acids," Broussard said. "The result was a significant loss of the benefits of insulin. This crucial hormone was less able to do its job. Insulin action in these healthy young men resembled what we typically see in early stages of diabetes."
Plasma free or non-esterified fatty acids are an important energy source for most body tissues. The demand for fatty acids goes up during exercise, for example, where they are used by cardiac and skeletal muscle; this preserves glucose for use by the brain. But constantly elevated fatty-acid levels in the blood are usually seen only in obese individuals as well as those with type 2 diabetes or cardiovascular disease. A 2012 study by a related research team emphasized the connections between sleep loss and the disruption of human fat cell function in energy regulation.
"This study opens the door to several intriguing questions," according to a Commentary in the journal by sleep specialists Jonathan Jun, MD, and Vsevolod Polotsky, MD, PhD, of Johns Hopkins University School of Medicine. Could variations in individual responses to short sleep explain susceptibility to metabolic consequences? Could dysregulation of fatty acid metabolism represent a common pathway linking various sleep disorders to metabolic syndrome? And why don't clinicians routinely ask their patients about sleep?
The study provides evidence for "potential mechanisms by which sleep restriction may be associated with insulin resistance and increased type 2 diabetes risk," the authors conclude. It supports the growing sense that insufficient sleep may disrupt fat metabolism. And it suggests that an intervention as simple as getting enough sleep could counteract the current epidemics of diabetes and obesity.
http://www.sciencedaily.com/releases/2015/02/150219084912.htm
Keep calm, anger can trigger a heart attack!
February 24, 2015
Science Daily/University of Sydney
http://images.sciencedaily.com/2015/02/150224083819-large.jpg
The risk of a heart attack is 8.5 times higher in the two hours following a burst of intense anger, researchers have found after investigating the link between acute emotional triggers and high risk of severe cardiac episodes. High levels of anxiety were associated with a 9.5 fold increased risk of triggering a heart attack in the two hours after an anxiety episode.
"Our findings confirm what has been suggested in prior studies and anecdotal evidence, even in films -- that episodes of intense anger can act as a trigger for a heart attack," said lead author Dr Thomas Buckley, Sydney Nursing School, University of Sydney, and researcher at Royal North Shore Hospital.
"The data shows that the higher risk of a heart attack isn't necessarily just while you're angry -- it lasts for two hours after the outburst.
In the study, 'anger' was qualified as 5 and above on a 1-7 scale, referring to 'very angry, body tense, clenching fists or teeth, ready to burst', up to 'enraged, out of control, throwing objects'. Anger below this level was not associated with increased risk.
"The triggers for these burst of intense anger were associated with arguments with family members (29 per cent), argument with others (42 per cent), work anger (14 per cent) and driving anger (14 per cent)," said Dr Buckley.
"The data also revealed that episodes of anxiety can also make you more likely to have heart attack.
"High levels of anxiety were associated with a 9.5 fold increased risk of triggering a heart attack in the two hours after the anxiety episode.
"Increased risk following intense anger or anxiety is most likely due to increased heart rate, blood pressure, tightening of blood vessels and increased clotting, all associated with triggering heart attacks," he said.
The study was an investigation of consecutive patients suspected of heart attack and confirmed by angiography reports at Royal North Shore hospital. Patients confirmed with acute coronary blockage were admitted, interviewed about their activities in the 48 hours before the onset of symptoms, and usual frequencies of activities were recorded for comparison.
"Although the incidence of anger-triggered heart attacks is around 2%, of the sample, those people were 8.5 times more likely to have a heart attack within two hours of the emotional episode. So while the absolute risk of any one episode triggering a heart attack is low, this data demonstrates that the danger is very present.
"Our findings highlight the need to consider strategies to protect individuals most at risk during times of acute anger.
Senior author Professor Geoffrey Tofler, Preventive Cardiology, University of Sydney said "Potential preventive approaches may be stress reduction training to reduce the frequency and intensity of episodes of anger, or avoiding activities that usually prompt such intense reactions, for instance, avoiding an angry confrontation or activity that provokes intense anxiety.
"Additionally, improving general health by minimising other risk factors, such as hypertension, high cholesterol or smoking would also lower risk.
"For those at high risk, it is possible that medication such as beta-blockers and aspirin taken at the time of a trigger may interrupt the link between the stressor and the heart attack. We are currently recruiting subjects for a study examining this option.
"Our research suggests that when managing a person with heart disease or in preventing heart disease in others, a person's frequency of anger and anxiety should also be assessed and be part of helping individuals to take care of themselves.
"Our message to people is they need to be aware that a burst of severe anger or anxiety could lead to a coronary event, so consider preventative strategies where possible," Dr Tofler said.
http://www.sciencedaily.com/releases/2015/02/150224083819.htm
Sleeping over 8 hours a day associated with greater risk of stroke
February 25, 2015
Science Daily/University of Cambridge
People who sleep for more than eight hours a day have an increased risk of stroke, according to a study -- and this risk doubles for older people who persistently sleep longer than average. However, the researchers say it is unclear why this association exists and call for further research to explore the link.
Previous studies have already suggested a possible association between sleep and risk of stroke, but today's study, published in the journal Neurology, is the first to provide detailed information about the British population and to examine the relationship between a change in sleep duration over time and subsequent stroke risk.
Researchers from the Department of Public Health and Primary Care at the University of Cambridge followed just under 10,000 people aged 42-81 years of age from the European Prospective Investigation into Cancer (EPIC)-Norfolk cohort over 9.5 years. During 1998-2000 and then again four years later, they asked the cohort how many hours on average they slept in a day and whether they generally slept well. Almost seven out of ten participants reported sleeping between six and eight hours a day, whilst one in ten reported sleeping for over eight hours a day. Participants who slept for less than six hours or more than eight hours were more likely to be older, women and less active.
Over the almost ten year period of the study, 346 participants suffered a stroke, either non-fatal or fatal stroke. After adjusting for various factors including age and sex, the researchers found that people who slept longer than eight hours a day were at a 46% greater risk of stroke than average. People who slept less than six hours a day were at an 18% increased risk, but the small number of people falling in this category meant the association was not statistically significant*.
Participants who reported persistently long sleep -- in other words, they reported sleeping over eight hours when asked at both points of the study -- were at double the risk of stroke compared to those with persistently average sleep duration (between six and eight hours a day). This risk was even greater for those whose reported sleep increased from short to long over the four years -- their risk was close to four times that of people who maintained an average sleep duration.
In addition to studying the EPIC-Norfolk cohort, the researchers carried out a study of combined data from 11 other studies related to identify the association between sleep duration and patterns of stroke risk. Their final analysis, including 560,000 participants from seven countries, supported the findings from the EPIC-Norfolk cohort study.
Yue Leng, a PhD candidate at the University of Cambridge, says: "It's apparent both from our own participants and the wealth of international data that there's a link between sleeping longer than average and a greater risk of stroke. What is far less clear, however, is the direction of this link, whether longer sleep is a symptom, an early marker or a cause of cardiovascular problems."
While older people have less work and fewer social demands and therefore often have the option of sleeping longer, previous research has shown that in fact, they tend to sleep on average for shorter periods.
The researchers say it is unclear yet why the link between sleep and stroke risk should exist. Lack of sleep has been linked with factors such as disrupted metabolism and raised levels of the 'stress hormone' cortisol, all of which may lead to higher blood pressure and increased stroke risk. However, the current study suggests that the association between longer sleep duration and higher risk of stroke was independent of normal risk factors for cardiovascular disease.
Professor Kay-Tee Khaw, senior author on the study, adds: "We need to understand the reasons behind the link between sleep and stroke risk. What is happening in the body that causes this link? With further research, we may find that excessive sleep proves to be an early indicator of increased stroke risk, particularly among older people."
http://www.sciencedaily.com/releases/2015/02/150225164004.htm
Sleep in America poll finds pain a significant challenge when it comes to Americans' sleep
March 2, 2015
Science Daily/National Sleep Foundation
A new poll in the United States finds that pain is a key factor in the gap between the amount of sleep Americans say they need and the amount they're getting -- an average 42 minute sleep debt for those with chronic pain and 14 minutes for those who've suffered from acute pain in the past week.
By contrast, there's no overall sleep debt for those without pain -- but significant numbers even in this group do have sleep problems. About one in three of those with no pain don't always or often get a good night's sleep or the sleep they need to feel their best, or have had trouble falling or staying asleep in the past week. Those problems rise even higher among individuals who do have chronic or acute pain.
The 2015 Sleep in America™ Poll finds that pain joins two related concerns -- stress and poor health -- as key correlates of shorter sleep durations and worse sleep quality. But there are paths to resolving the problem: The sleep gap narrows sharply among those who make sleep a priority.
"Taking control of your sleep by being motivated, setting a routine bedtime and creating a supportive sleep environment are relevant even for those with pain," said David Cloud, CEO of the National Sleep Foundation. "Sleep is a key marker of health, and good sleep habits are critical for improving the quality of life of those living with chronic or acute pain."
Pain is prevalent, and sleep suffers
The national, random-sample survey establishes the broad impacts of pain-related sleep loss on millions of Americans. The problem is a notable one given the number of Americans who suffer from pain. The study finds that 21 percent of Americans experience chronic pain and 36 percent have had acute pain in the past week. Those combine to a majority of the nation's adult population, 57 percent, leaving 43 percent who report being pain free.
Beyond sleep debt, self-reported sleep quality and stress levels underscore the effects of pain on sleep.
Sixty-five percent of those with no pain reported good or very good sleep quality, while only 45 percent of those with acute pain and 37 percent of those with chronic pain did the same. Additionally, 23 percent of those with chronic pain reported higher stress levels, compared with 7 percent of those without pain.
Those with acute or chronic pain are more likely to have sleep problems impact their daily lives. Among people who've had sleep difficulties in the past week, more than half of those with chronic pain say those difficulties interfered with their work. That drops to 23 percent of those without pain. People with pain are also far more apt than others to report that lack of sleep interferes with their mood, activities, relationships and enjoyment of life overall.
People with pain also feel less control over their sleep, worry more about lack of sleep affecting their health and exhibit greater sleep sensitivity. They're more likely than others to say environmental factors make it more difficult for them to get a good night's sleep. These factors include noise, light, temperature and their mattresses alike, suggesting that taking greater care of the bedroom environment may be particularly helpful to pain sufferers.
While both chronic and acute pain relate to lost sleep, the survey indicates that chronic pain is an especially powerful problem. Indeed, nearly one in four people with chronic pain, 23 percent, say they've been diagnosed with a sleep disorder by a doctor, compared with just 6 percent of all others.
"Clinicians and pain sufferers know that pain and sleep problems present together and aggravate each other. This poll confirms the relationship between pain and sleep. Fortunately, it also shows that simple steps to improving sleep can be beneficial," said Dr. Timothy Roehrs, PhD, Henry Ford Hospital.
Sleep is a key indicator of overall health
Americans who say they have very good or excellent health and quality of life report sleeping 18 to 23 minutes longer on average in the past week than those who rate their health and quality of life as just good, fair or poor. Indeed, reported sleep duration and quality decline linearly with each health rating, showing that perceptions of one's sleep and health are deeply related.
"Sleep quality and duration should be considered a vital sign, as they are strong indicators of overall health and quality of life," said Kristen Knutson, PhD, National Sleep Foundation Sleep in America™ Poll Scholar. "Extremely long or short sleep durations are associated with more specific conditions, but for many people who are close to getting the recommended seven to nine hours of sleep, getting just 15 to 30 minutes more sleep a night could make difference in how they feel."
Making sleep a priority is linked to better sleep, even among those with pain
Americans who said they were very or extremely motivated to get enough sleep reported sleeping 36 more minutes per night across the week compared with others (7.3 vs. 6.7 hours). Even among those with pain, a higher motivation to get sleep was associated with longer sleep durations and better sleep quality.
"Understanding the importance of sleep and taking a proactive approach to bed times can help everyone improve their sleep, even people with pain," said Knutson. "Taking control of your sleep is an important step in taking control of your health."
http://www.sciencedaily.com/releases/2015/03/150302182345.htm
Losing 30 minutes of sleep per day may promote weight gain and adversely affect blood sugar control
March 6, 2015
Science Daily/Endocrine Society
Losing as little as 30 minutes of sleep per day on weekdays can have long-term consequences for body weight and metabolism, a new study finds.
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"While previous studies have shown that short sleep duration is associated with obesity and diabetes, we found that as little as 30 minutes a day sleep debt can have significant effects on obesity and insulin resistance at follow up," said lead study author Professor Shahrad Taheri, MBBS, PhD, professor of medicine at Weill Cornell Medical College in Qatar, in Doha. "This reinforces earlier observations that sleep loss is additive and can have metabolic consequences."
Because of social and work commitments, people often accumulate sleep debt during weekdays and make up for lost sleep over the weekend. But weekday sleep debt may lead to long-term metabolic disruption, which may promote the onset of, or exacerbate the progression of, type 2 diabetes mellitus.
"Sleep loss is widespread in modern society, but only in the last decade have we realized its metabolic consequences," Taheri said. "Our findings suggest that avoiding sleep debt could have positive benefits for waistlines and metabolism and that incorporating sleep into lifestyle interventions for weight loss and diabetes might improve their success."
Professor Taheri and his colleagues recruited 522 patients with newly diagnosed type 2 diabetes mellitus in the Early Activity in Diabetes trial and randomized them into one of three groups: usual care, physical activity intervention, or diet and physical activity intervention.
Participants completed 7-day sleep diaries and calculated their weekday sleep debt. At baseline, the researchers recorded their height and weight to determine obesity status, measured their waist circumference for central adiposity, and analyzed their fasting blood samples for insulin sensitivity.
At baseline, compared with participants who had no weekday sleep debt, those who had weekday sleep debt were 72% more likely to be obese, and by the 6-month mark, weekday sleep debt was significantly associated with obesity and insulin resistance.
At 12 months, for every 30 minutes of weekday sleep debt at baseline, the risk of obesity and insulin resistance was significantly increased by 17% and 39%, respectively.
The authors advise that future interventions designed to slow progression or reverse metabolic disease should consider all factors -- including sleep -- that affect metabolic function. Looking toward future research, they recommend that consistent optimum sleep hygiene and education may be a key component of successful future trials in metabolic disease control.
http://www.sciencedaily.com/releases/2015/03/150306082541.htm
Moderate alcohol consumption increases attractiveness
March 9, 2015
Science Daily/University of Bristol
Consuming alcohol (equivalent to about a glass of wine) can make the drinker appear more attractive than when sober, according to new research. However, the effect disappears when more is consumed.
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Professor Marcus Munafò and colleagues in Bristol's School of Experimental Psychology asked a group of heterosexual social alcohol consumers (20 women and 20 men) to complete an attractiveness-rating task.
The volunteers were presented with images depicting an individual photographed while sober and after consuming either the equivalent of 250ml of wine or the equivalent of 500ml of wine. They were then asked to rate which of the two images was more attractive.
Photographs of individuals who had consumed the equivalent of a single glass were rated as more attractive than photographs of sober individuals. However, this was not the case for photographs of individuals who had consumed more than the equivalent of a glass.
This change in attractiveness is presumably driven by changes in appearance. The researchers suggest that vasodilation associated with alcohol consumption could lead to an increase in facial flushing, which is perceived as healthy and attractive. Low doses of alcohol may also result in an increase in positive mood that is apparent in subtle smiles and more muscle relaxation.
Understanding the mechanisms through which alcohol influences social behaviour, including factors that may impact on the likelihood of engaging in risky sexual behaviour, is important if we are to develop evidence-based public health messages, the researchers said.
http://www.sciencedaily.com/releases/2015/03/150309211523.htm
Brain waves predict our risk for insomnia
March 11, 2015
Science Daily/Concordia University
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There may not yet be a cure for insomnia, but researchers are a step closer to predicting who is most likely to suffer from it -- just in time for World Sleep Day on March 13. Researchers note that we should all keep abiding by the habits already acknowledged to promote a good night's sleep: "Avoid sources of stress when going to bed, preserve the bedroom environment for sleep and not for work, and avoid stimulation. Find ways to relax before going to sleep."
To determine the role of stress, the study examined the sleep cycles of 12 Concordia students as they went through the nerve-racking experience of finals. Measuring students' brain waves at the beginning of the school semester, Dang-Vu and his team found that students showing a lower amount of a particular pattern of brain waves were more at risk for developing insomnia afterwards in response to the stress of the exams.
The brain -- specifically the deep, inner parts of the brain called the thalamus and cortex -- produces electromagnetic activity during sleep. When monitored by diagnostic tools, this activity appears as patterns of squiggly lines that scientists refer to as spindles.
In a previous experiment, Dang-Vu and his team discovered that greater spindle activity helps sleepers resist waking, despite noise. The new study aimed to test whether there would be a similar relationship between spindles and stress.
The hypothesis proved true. "We found that those who had the lowest spindle activity tended to develop more disturbances in response to stress, when comparing sleep quality at the beginning of the semester and the end of the school semester," Dang-Vu says.
"We are not all equally armed when facing stress, in terms of how we can manage our sleep.
Some people are more vulnerable than others."
So how do you get these better spindles? Are there meditation practices you can adopt? Will gyms begin introducing spindle classes? Unfortunately, there's not a lot you can do at the moment, since spindles seem to be at least partially dependent on genetics.
But Dang-Vu, who is a medical doctor and neurologist at the Institut Universitaire de Gériatrie de Montréal, says that exploring ways to improve spindles is another prospective area for research. Measuring spindle activity may also help identify people at risk of insomnia before the condition materializes.
In the meantime, we should all keep abiding by the habits already acknowledged to promote a good night's sleep, Dang-Vu says. "Avoid sources of stress when going to bed, preserve the bedroom environment for sleep and not for work, and avoid stimulation. Find ways to relax before going to sleep."
http://www.sciencedaily.com/releases/2015/03/150311124435.htm
Prolonged shortened sleep increases blood pressure at night
March 13, 2015
Science Daily/Mayo Clinic
People exposed to prolonged periods of shortened sleep have significant increases in blood pressure during nighttime hours, researchers report in a small study of eight participants.
In this study, eight healthy, normal weight participants, ages 19 to 36, participated in a 16-day inpatient protocol, consisting of a four-day acclimation period followed by nine days of either sleep restriction (four hours of sleep per night) or normal sleep (nine hours of sleep per night), and three days of recovery. Twenty-four blood pressure monitoring at regular intervals was measured at each study phase.
During the nighttime, in the sleep restriction phase compared to the normal sleep phase, systolic (top number) and diastolic (bottom number) blood pressure averaged 115/64 millimeters of mercury (mm Hg) versus 105/57 mm Hg, respectively, researchers found. Furthermore, the expected fall in blood pressure during the night was suppressed when subjects had inadequate sleep. They also found that nighttime heart rate was higher with sleep restriction than in normal sleep.
"We know high blood pressure, particularly during the night, is one of the major risk factors for heart disease, and Americans typically do not get enough sleep," says lead author Naima Covassin, Ph.D., Mayo Clinic cardiovascular diseases research fellow. "For the first time, we demonstrated that insufficient sleep causes increases in nighttime blood pressure and dampens nocturnal blood pressure dipping by using a controlled study that mimics the sleep loss experienced by many people."
http://www.sciencedaily.com/releases/2015/03/150313130739.htm
Is too much artificial light at night making us sick?
March 18, 2015
Science Daily/University of Connecticut
Modern life, with its preponderance of inadequate exposure to natural light during the day and overexposure to artificial light at night, is not conducive to the body's natural sleep/wake cycle. A cancer epidemiologist and team members suggest such overexposure has possible ties to cancer, obesity, diabetes, and other health issues.
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It's an emerging topic in health, one that UConn Health (University of Connecticut, Farmington, Conn.) cancer epidemiologist Richard Stevens has been studying for three decades.
"It's become clear that typical lighting is affecting our physiology," Stevens says. "But lighting can be improved. We're learning that better lighting can reduce these physiological effects. By that we mean dimmer and longer wavelengths in the evening, and avoiding the bright blue of e-readers, tablets and smart phones."
Those devices emit enough blue light when used in the evening to suppress the sleep-inducing hormone melatonin and disrupt the body's circadian rhythm, the biological mechanism that enables restful sleep.
Stevens and co-author Yong Zhu from Yale University explain the known short-term and suspected long-term impacts of circadian disruption in an invited article published in the British journal Philosophical Transactions of the Royal Society B.
"It's a new analysis and synthesis of what we know up to now on the effect of lighting on our health," Stevens says. "We don't know for certain, but there's growing evidence that the long-term implications of this have ties to breast cancer, obesity, diabetes, and depression, and possibly other cancers."
As smartphones and tablets become more commonplace, Stevens recommends a general awareness of how the type of light emitted from these devices affects our biology. He says a recent study comparing people who used e-readers to those who read old-fashioned books in the evening showed a clear difference -- the e-readers showed delayed melatonin onset.
"It's about how much light you're getting in the evening," Stevens says. "It doesn't mean you have to turn all the lights off at 8 every night, it just means if you have a choice between an e-reader and a book, the book is less disruptive to your body clock. At night, the better, more circadian-friendly light is dimmer and, believe it or not, redder, like an incandescent bulb."
http://www.sciencedaily.com/releases/2015/03/150318153947.htm