Tag Archives: sleep

Circadian Misalignment and Your Smartphone

Google-search-smartphone-night

You take your portable electronics everywhere, all the time. You watch TV with or on your smartphone. You eat with a fork in one hand and your smartphone in the other. In fact, you probably wish you had two pairs of arms so you could eat, drink and use your smartphone and laptop at the same time. You use your smartphone in your car — hopefully or sensibly not while driving. You read texts on your smartphone while in the restroom. You use it at the movie theater, at the theater (much to the dismay of stage actors). It’s with you at the restaurant, on the bus or metro, in the aircraft, in the bath (despite chances of getting electrically shocked). You check your smartphone first thing in the morning and last thing before going to sleep. And, if your home or work-life demands you will check it periodically throughout the night.

Let’s leave aside for now the growing body of anecdotal and formal evidence that smartphones are damaging your physical wellbeing. This includes finger, hand and wrist problems (from texting); and neck and posture problems (from constantly bending over your small screen). Now there is evidence that constant use, especially at night, is damaging your mental wellbeing and increasing the likelihood of additional, chronic physical ailments. It appears that the light from our constant electronic companions is not healthy, particularly as it disrupts our regular rhythm of sleep.

From Wired:

For More than 3 billion years, life on Earth was governed by the cyclical light of sun, moon and stars. Then along came electric light, turning night into day at the flick of a switch. Our bodies and brains may not have been ready.

A fast-growing body of research has linked artificial light exposure to disruptions in circadian rhythms, the light-triggered releases of hormones that regulate bodily function. Circadian disruption has in turn been linked to a host of health problems, from cancer to diabetes, obesity and depression. “Everything changed with electricity. Now we can have bright light in the middle of night. And that changes our circadian physiology almost immediately,” says Richard Stevens, a cancer epidemiologist at the University of Connecticut. “What we don’t know, and what so many people are interested in, are the effects of having that light chronically.”

Stevens, one of the field’s most prominent researchers, reviews the literature on light exposure and human health the latest Philosophical Transactions of the Royal Society B. The new article comes nearly two decades after Stevens first sounded the alarm about light exposure possibly causing harm; writing in 1996, he said the evidence was “sparse but provocative.” Since then, nighttime light has become even more ubiquitous: an estimated 95 percent of Americans regularly use screens shortly before going to sleep, and incandescent bulbs have been mostly replaced by LED and compact fluorescent lights that emit light in potentially more problematic wavelengths. Meanwhile, the scientific evidence is still provocative, but no longer sparse.

As Stevens says in the new article, researchers now know that increased nighttime light exposure tracks with increased rates of breast cancer, obesity and depression. Correlation isn’t causation, of course, and it’s easy to imagine all the ways researchers might mistake those findings. The easy availability of electric lighting almost certainly tracks with various disease-causing factors: bad diets, sedentary lifestyles, exposure to they array of chemicals that come along with modernity. Oil refineries and aluminum smelters, to be hyperbolic, also blaze with light at night.

Yet biology at least supports some of the correlations. The circadian system synchronizes physiological function—from digestion to body temperature, cell repair and immune system activity—with a 24-hour cycle of light and dark. Even photosynthetic bacteria thought to resemble Earth’s earliest life forms have circadian rhythms. Despite its ubiquity, though, scientists discovered only in the last decade what triggers circadian activity in mammals: specialized cells in the retina, the light-sensing part of the eye, rather than conveying visual detail from eye to brain, simply signal the presence or absence of light. Activity in these cells sets off a reaction that calibrates clocks in every cell and tissue in a body. Now, these cells are especially sensitive to blue wavelengths—like those in a daytime sky.

But artificial lights, particularly LCDs, some LEDs, and fluorescent bulbs, also favor the blue side of the spectrum. So even a brief exposure to dim artificial light can trick a night-subdued circadian system into behaving as though day has arrived. Circadian disruption in turn produces a wealth of downstream effects, including dysregulation of key hormones. “Circadian rhythm is being tied to so many important functions,” says Joseph Takahashi, a neurobiologist at the University of Texas Southwestern. “We’re just beginning to discover all the molecular pathways that this gene network regulates. It’s not just the sleep-wake cycle. There are system-wide, drastic changes.” His lab has found that tweaking a key circadian clock gene in mice gives them diabetes. And a tour-de-force 2009 study put human volunteers on a 28-hour day-night cycle, then measured what happened to their endocrine, metabolic and cardiovascular systems.

Crucially, that experiment investigated circadian disruption induced by sleep alteration rather than light exposure, which is also the case with the many studies linking clock-scrambling shift work to health problems. Whether artificial light is as problematic as disturbed sleep patterns remains unknown, but Stevens thinks that some and perhaps much of what’s now assumed to result from sleep issues is actually a function of light. “You can wake up in the middle of the night and your melatonin levels don’t change,” he says. “But if you turn on a light, melatonin starts falling immediately. We need darkness.” According to Stevens, most people live in a sort of “circadian fog.”

Read the entire article here.

Image courtesy of Google Search.

Nightmares And Art

Sleep-Nicolas-Bruno

You probably believe that your nightmares are best left locked in a dark closet. On the other hand, artist Nicolas Bruno believes they make good art.

See more of Bruno’s nightmarish images here.

From the Guardian:

Sufferer of sleep paralysis Nicolas Bruno transforms his terrifying dreams into photographic realities. The characters depicted are often stuck within their scenes, unable to escape. The 20 year old New York native suggests ‘Sleep paralysis is an experience in which the individual becomes conscious and is left immobile in a state between being awake and asleep.’

Image courtesy of Nicolas Bruno / Hot Spot Media.

 

Why Sleep?

There are more theories on why we sleep than there are cable channels in the U.S. But that hasn’t prevented researchers from proposing yet another one — it’s all about flushing waste.

From the Guardian:

Scientists in the US claim to have a new explanation for why we sleep: in the hours spent slumbering, a rubbish disposal service swings into action that cleans up waste in the brain.

Through a series of experiments on mice, the researchers showed that during sleep, cerebral spinal fluid is pumped around the brain, and flushes out waste products like a biological dishwasher.

The process helps to remove the molecular detritus that brain cells churn out as part of their natural activity, along with toxic proteins that can lead to dementia when they build up in the brain, the researchers say.

Maiken Nedergaard, who led the study at the University of Rochester, said the discovery might explain why sleep is crucial for all living organisms. “I think we have discovered why we sleep,” Nedergaard said. “We sleep to clean our brains.”

Writing in the journal Science, Nedergaard describes how brain cells in mice shrank when they slept, making the space between them on average 60% greater. This made the cerebral spinal fluid in the animals’ brains flow ten times faster than when the mice were awake.

The scientists then checked how well mice cleared toxins from their brains by injecting traces of proteins that are implicated in Alzheimer’s disease. These amyloid beta proteins were removed faster from the brains of sleeping mice, they found.

Nedergaard believes the clean-up process is more active during sleep because it takes too much energy to pump fluid around the brain when awake. “You can think of it like having a house party. You can either entertain the guests or clean up the house, but you can’t really do both at the same time,” she said in a statement.

According to the scientist, the cerebral spinal fluid flushes the brain’s waste products into what she calls the “glymphatic system” which carries it down through the body and ultimately to the liver where it is broken down.

Other researchers were sceptical of the study, and said it was too early to know if the process goes to work in humans, and how to gauge the importance of the mechanism. “It’s very attractive, but I don’t think it’s the main function of sleep,” said Raphaelle Winsky-Sommerer, a specialist on sleep and circadian rhythms at Surrey University. “Sleep is related to everything: your metabolism, your physiology, your digestion, everything.” She said she would like to see other experiments that show a build up of waste in the brains of sleep-deprived people, and a reduction of that waste when they catch up on sleep.

Vladyslav Vyazovskiy, another sleep expert at Surrey University, was also sceptical. “I’m not fully convinced. Some of the effects are so striking they are hard to believe. I would like to see this work replicated independently before it can be taken seriously,” he said.

Jim Horne, professor emeritus and director of the sleep research centre at Loughborough University, cautioned that what happened in the fairly simple mouse brain might be very different to what happened in the more complex human brain. “Sleep in humans has evolved far more sophisticated functions for our cortex than that for the mouse, even though the present findings may well be true for us,” he said.

But Nedergaard believes she will find the same waste disposal system at work in humans. The work, she claims, could pave the way for medicines that slow the onset of dementias caused by the build-up of waste in the brain, and even help those who go without enough sleep. “It may be that we can reduce the need at least, because it’s so annoying to waste so much time sleeping,” she said.

Read the entire article here.

Image courtesy of Telegraph.

Night Owls, Beware!

A new batch of research points to a higher incidence of depression in night owls than in early risers. Further studies will be required to determine a true causal link, but initial evidence seems to suggest that those who stay up late have structural differences in the brain leading to a form of chronic jet lag.

From Washington Post:

They say the early bird catches the worm, but night owls may be missing far more than just a tasty snack. Researchers have discovered evidence of structural brain differences that distinguish early risers from people who like to stay up late. The differences might help explain why night owls seem to be at greater risk of depression.

About 10 percent of people are morning people, or larks, and 20 percent are night owls, with the rest falling in between. Your status is called your chronotype.

Previous studies have suggested that night owls experience worse sleep, feel more tiredness during the day and consume greater amounts of tobacco and alcohol. This has prompted some to suggest that they are suffering from a form of chronic jet lag.

Jessica Rosenberg at RWTH Aachen University in Germany and colleagues used a technique called diffusion tensor imaging to scan the brains of 16 larks, 23 night owls and 20 people with intermediate chronotypes. They found a reduction in the integrity of night owls’ white matter — brain tissue largely made up of fatty insulating material that speeds up the transmission of nerve signals — in areas associated with depression.

“We think this could be caused by the fact that late chronotypes suffer from this permanent jet lag,” Rosenberg says, although she cautions that further studies are needed to confirm cause and effect.

Read the entire article here.

Image courtesy of Google search.

Sleep Myths

Chronobiologist, Till Roenneberg, debunks 5 commonly held beliefs about sleep. He is author of “Internal Time: Chronotypes, Social Jet Lag, and Why You’re So Tired.

[div class=attrib]From the Washington Post:[end-div]

If shopping on Black Friday leaves you exhausted, or if your holiday guests keep you up until the wee hours, a long Thanksgiving weekend should offer an opportunity for some serious shut-eye. We spend between a quarter and a third of our lives asleep, but that doesn’t make us experts on how much is too much, how little is too little, or how many hours of rest the kids need to be sharp in school. Let’s tackle some popular myths about Mr. Sandman.

1.You need eight hours of sleep per night.

That’s the cliche. Napoleon, for one, didn’t believe it. His prescription went something like this: “Six hours for a man, seven for a woman and eight for a fool.”

But Napoleon’s formula wasn’t right, either. The ideal amount of sleep is different for everyone and depends on many factors, including age and genetic makeup.

In the past 10 years, my research team has surveyed sleep behavior in more than 150,000 people. About 11 percent slept six hours or less, while only 27 percent clocked eight hours or more. The majority fell in between. Women tended to sleep longer than men, but only by 14 minutes.

Bigger differences are seen when comparing various age groups. Ten-year-olds needed about nine hours of sleep, while adults older than 30, including senior citizens, averaged about seven hours. We recently identified the first gene associated with sleep duration — if you have one variant of this gene, you need more sleep than if you have another.

2. Early to bed and early to rise makes a man healthy, wealthy and wise.

Benjamin Franklin’s proverbial praise of early risers made sense in the second half of the 18th century, when his peers were exposed to much more daylight and to very dark nights. Their body clocks were tightly synchronized to this day-night cycle. This changed as work gradually moved indoors, performed under the far weaker intensity of artificial light during the day and, if desired, all night long.

The timing of sleep — earlier or later — is controlled by our internal clocks, which determine what researchers call our optimal “sleep window.” With the widespread use of electric light, our body clocks have shifted later while the workday has essentially remained the same. We fall asleep according to our (late) body clock, and are awakened early for work by the alarm clock. We therefore suffer from chronic sleep deprivation, and then we try to compensate by sleeping in on free days. Many of us sleep more than an hour longer on weekends than we do on workdays.

[div class=attrib]Read the entire article following the jump.[end-div]

[div class=attrib]Image courtesy of Google search.[end-div]

Teenagers and Time

Parents have long known that the sleep-wake cycles of their adolescent offspring are rather different to those of anyone else in the household.

Several new and detailed studies of teenagers tell us why teens are impossible to awaken at 7 am, suddenly awake at 10 pm, and often able to sleep anywhere for stretches of 16 hours.

[div class=attrib]From the Wall Street Journal:[end-div]

Many parents know the scene: The groggy, sleep-deprived teenager stumbles through breakfast and falls asleep over afternoon homework, only to spring to life, wide-eyed and alert, at 10 p.m.—just as Mom and Dad are nodding off.

Fortunately for parents, science has gotten more sophisticated at explaining why, starting at puberty, a teen’s internal sleep-wake clock seems to go off the rails. Researchers are also connecting the dots between the resulting sleep loss and behavior long chalked up to just “being a teenager.” This includes more risk-taking, less self-control, a drop in school performance and a rise in the incidence of depression.

One 2010 study from the University of British Columbia, for example, found that sleep loss can hamper neuron growth in the brain during adolescence, a critical period for cognitive development.

Findings linking sleep loss to adolescent turbulence are “really revelatory,” says Michael Terman, a professor of clinical psychology and psychiatry at Columbia University Medical Center and co-author of “Chronotherapy,” a forthcoming book on resetting the body clock. “These are reactions to a basic change in the way teens’ physiology and behavior is organized.”

Despite such revelations, there are still no clear solutions for the teen-zombie syndrome. Should a parent try to enforce strict wake-up and bedtimes, even though they conflict with the teen’s body clock? Or try to create a workable sleep schedule around that natural cycle? Coupled with a trend toward predawn school start times and peer pressure to socialize online into the wee hours, the result can upset kids’ health, school performance—and family peace.

Jeremy Kern, 16 years old, of San Diego, gets up at 6:30 a.m. for school and tries to fall asleep by 10 p.m. But a heavy load of homework and extracurricular activities, including playing saxophone in his school marching band and in a theater orchestra, often keep him up later.

“I need 10 hours of sleep to not feel tired, and every single day I have to deal with being exhausted,” Jeremy says. He stays awake during early-afternoon classes “by sheer force of will.” And as research shows, sleep loss makes him more emotionally volatile, Jeremy says, like when he recently broke up with his girlfriend: “You are more irrational when you’re sleep deprived. Your emotions are much harder to control.”

Only 7.6% of teens get the recommended 9 to 10 hours of sleep, 23.5% get eight hours and 38.7% are seriously sleep-deprived at six or fewer hours a night, says a 2011 study by the Centers for Disease Control and Prevention.

It’s a biological 1-2-3 punch. First, the onset of puberty brings a median 1.5-hour delay in the body’s release of the sleep-inducing hormone melatonin, says Mary Carskadon, a professor of psychiatry and human behavior at the Brown University medical school and a leading sleep researcher.

Second, “sleep pressure,” or the buildup of the need to sleep as the day wears on, slows during adolescence. That is, kids don’t become sleepy as early. This sleep delay isn’t just a passing impulse: It continues to increase through adolescence, peaking at age 19.5 in girls and age 20.9 in boys, Dr. Carskadon’s research shows.

Finally, teens lose some of their sensitivity to morning light, the kind that spurs awakening and alertness. And they become more reactive to nighttime light, sparking activity later into the evening.

[div class=attrib]Read the entire article after the jump.[end-div]

[div class=attrib]Image courtesy of the Guardian / Alamy.[end-div]

Sleep: Defragmenting the Brain

[div class=attrib]From Neuroskeptic:[end-div]

After a period of heavy use, hard disks tend to get ‘fragmented’. Data gets written all over random parts of the disk, and it gets inefficient to keep track of it all.

That’s why you need to run a defragmentation program occasionally. Ideally, you do this overnight, while you’re asleep, so it doesn’t stop you from using the computer.

A new paper from some Stanford neuroscientists argues that the function of sleep is to reorganize neural connections – a bit like a disk defrag for the brain – although it’s also a bit like compressing files to make more room, and a bit like a system reset: Synaptic plasticity in sleep: learning, homeostasis and disease

The basic idea is simple. While you’re awake, you’re having experiences, and your brain is forming memories. Memory formation involves a process called long-term potentiation (LTP) which is essentially the strengthening of synaptic connections between nerve cells.

Yet if LTP is strengthening synapses, and we’re learning all our lives, wouldn’t the synapses eventually hit a limit? Couldn’t they max out, so that they could never get any stronger?

Worse, the synapses that strengthen during memory are primarily glutamate synapses – and these are dangerous. Glutamate is a common neurotransmitter, and it’s even a flavouring, but it’s also a toxin.

Too much glutamate damages the very cells that receive the messages. Rather like how sound is useful for communication, but stand next to a pneumatic drill for an hour, and you’ll go deaf.

So, if our brains were constantly forming stronger glutamate synapses, we might eventually run into serious problems. This is why we sleep, according to the new paper. Indeed, sleep deprivation is harmful to health, and this theory would explain why.

[div class=attrib]More from theSource here.[end-div]