Sleep - Page 16 of 17

Why Some People Only Need Five Hours’ Sleep a Night

Study of twins explains how some people can function normally on 5 hours sleep.

Study of twins explains how some people can function normally on 5 hours sleep.

A gene mutation which means a person can function normally with only five hours’ sleep a night has been identified by a study of 100 pairs of twins.

While most people can get by with less than six hours, the majority will suffer physically and psychologically, especially if sleep deprived over the long-term.

But this group of people with a variant of the ‘BHLHE41’ gene only need an average of five hours and likely suffer no ill-effects.

This type of twin study takes advantage of similarities and differences in the genetic code of identical and non-identical twins.

The 100 pairs of twins had their normal sleeping patterns measured, and then they were deprived of sleep for 38 hours (Pellegrino et al., 2014).

The results, published in the journal Sleep, showed that those carrying the target gene variant slept, on average, for five hours, which was one hour shorter than their twins without the gene.

When the twins were given cognitive tests after the sleep deprivation, those with the gene variant did better, making 40% fewer errors.

Not only that, but the carriers recovered more quickly from sleep deprivation, only requiring 8 hours recovery sleep, compared with their twins who needed 9.5 hours.

Dr. Renata Pellegrino, who is the study’s lead author, said:

“This work provides an important second gene variant associated with sleep deprivation and for the first time shows the role of BHLHE41 in resistance to sleep deprivation in humans.
The mutation was associated with resistance to the neurobehavioral effects of sleep deprivation.”

How much is enough?

The American Academy of Sleep Medicine recommends between 7 and 9 hours sleep for most people.

The Academy’s President, Dr. Timothy Morgenthaler, said:

“This study emphasizes that our need for sleep is a biological requirement, not a personal preference.
Most adults appear to need at least seven hours of quality sleep each night for optimal health, productivity and daytime alertness.”

For the vast majority of people, regularly getting less than about 7 hours of sleep leads to concentration problems, lower energy levels, accidents and, in the long-term, raises the risk of depression.

The lucky few with this genetic mutation, though, can break this basic rule of sleeping.

Image credit: surlygirl

When You Sleep and Wake Up is Controlled by a Single Gene

This research could lead to a cure for jet-lag and other sleep problems.

Researchers at the Salk Institute for Biological Studies have found that a single gene regulates daily sleeping and waking cycles (Hatori et al., 2014).

Understanding the function of the gene, called Lhx1, may help to create therapies for jet-lagged travellers, night-shift workers and those with problems sleeping.

Satchidananda Panda, who led the research, says that even dementias may be helped by potential therapies:

“It’s possible that the severity of many dementias comes from sleep disturbances.
If we can restore normal sleep, we can address half of the problem.”

The study examined the sleep and wake cycles of mice, concentrating on an area of the brain called the suprachiasmatic nucleus, or the SCN.

The SCN is a densely packed region of around 20,000 neurons in the hypothalamus, which establish our daily biological rhythms.

Sometimes known as the ‘master clock’, the SCN effectively tells every cell in the body what time it is.

Our internal clock is reset by light, which is why we tend to suffer from jet lag: our daily biological cycles get scrambled.

The researchers in this study effectively gave jet lag to the mice by shifting their usual day-night cycle by 8 hours.

They then looked at the expression of 213 genes and were surprised to find that just one was suppressed in response to light, T

The finding was a particular surprise because previously the gene had never been intricately linked with SCN function.

They found that mice that had little or no Lhx1 were able to adjust to the jet-lag much faster than other mice.

The scientists hope that this brings them one step closer to new cell regenerative therapies for sleep problems.

Image credit: Mark Sebastian

Poor Sleep Can Lead to False Memories

Short of sleep? Your memory could be playing serious tricks on you.

We all know that lack of sleep affects our memory, along with other cognitive abilities.

Sitting in the office, sleep deprived, it’s difficult to remember your own name, let along the ever-lengthening to-do list.

But now new research shows that not getting enough sleep increases the chances your mind will actually create false memories.

The study, published in Psychological Science, allowed one group of participants to get a full nights’ sleep, while another had to stay up all night (Frenda et al., 2014).

In the morning they were given a series of photos that were supposed to show a crime being committed.

Next, both groups were given some eyewitness statements about the crime.

Like many witness statements in real-life crimes, the details were different to those shown in the photographs.

For example, in one instance the photo showed a thief putting a wallet in his jacket, but in the witness statement it said he put it in his pants (that’s ‘trousers’ for British people, not his underwear!).

Afterwards, they were asked what they had seen in the original photographs.

The results showed that those who’d missed out on their sleep were the most likely to regurgitate the false eyewitness statements they’d just read, rather than remembering the ‘true’ crime-scene photos they’d been shown moments beforehand.

The lack of sleep had messed with their heads to the extent that all the evidence — right and wrong — had got mixed up.

One of the study’s authors, Kimberly Fenn, said:

“People who repeatedly get low amounts of sleep every night could be more prone in the long run to develop these forms of memory distortion.
It’s not just a full night of sleep deprivation that puts them at risk.”

Indeed, a preliminary study they carried out found that getting just five hours sleep was enough to cause people to start manufacturing false memories.

→ Related: 10 Sleep Deprivation Effects.

Image credit: Dan Foy

Poor Sleep: 8 Hours With Interruptions As Bad As Only 4 Hours

Four 10 to 15 minute sleep interruptions in the night enough to leave people groggy and grumpy.

A full night’s sleep which is interrupted can be as bad as getting only half a night, finds a new study taking a novel approach to sleep problems.

Despite how common it is for parents of young children to be awakened many times during the night, the effects have never been systematically investigated.

Parents are not the only ones who suffer, explains Prof. Avi Sadeh, who led the new research:

“Doctors on call, who may receive several phone calls a night, also experience disruptions.
These night wakings could be relatively short — only five to ten minutes — but they disrupt the natural sleep rhythm.
The impact of such night wakings on an individual’s daytime alertness, mood, and cognitive abilities had never been studied.
Our study is the first to demonstrate seriously deleterious cognitive and emotional effects.”

In their study participants were awakened four times during a normal 8-hour night (Kahn et al., 2014).

Each time they had to complete a computer task that took 10-15 minutes before they went back to bed.

In the morning they took tests of alertness, attention and mood. These were compared with results from two other nights when they’d had either:

An uninterrupted 8 hours.
An artificially restricted 4 hours.

The effects on mood, attention and alertness for the interrupted 8 hours were as drastic as only getting 4 hours sleep.

In comparison to the uninterrupted 8 hours, people felt more depressed, fatigued, confused and lower in vigour.

And this was the effect of just one interrupted night.

These deleterious effects can snowball, as Sadeh explained:

“Our study shows the impact of only one disrupted night.
But we know that these effects accumulate and therefore the functional price new parents — who awaken three to ten times a night for months on end — pay for common infant sleep disturbance is enormous.
Besides the physical effects of interrupted sleep, parents often develop feelings of anger toward their infants and then feel guilty about these negative feelings.”

Image credit: Simon Pais-Thomas

How Sleep After Learning Enhances Memory

The physical changes in the motor cortex that result from learning and sleep.

Sleep after learning encourages brain cells to make connections with other brain cells, research shows for the first time.

The connections, called dendritic spines, enable the flow of information across the synapses.

The findings, published in the prestigious journal Science, are the first to show physical changes in the motor cortex resulting from learning and sleep (Yang et al., 2014).

One of the study’s authors, Wen-Biao Gan, PhD, said:

“We’ve known for a long time that sleep plays an important role in learning and memory. If you don’t sleep well you won’t learn well.
But what’s the underlying physical mechanism responsible for this phenomenon?
Here we’ve shown how sleep helps neurons form very specific connections on dendritic branches that may facilitate long-term memory.
We also show how different types of learning form synapses on different branches of the same neurons, suggesting that learning causes very specific structural changes in the brain.”

The results come from studies in mice, which were genetically engineered with a fluorescent protein in their neurons.

With the use of a laser-scanning microscope, the fluorescent protein allowed the scientists to track and image the dendritic spines before and after they learnt a new skill; in this case balancing on a spinning rod.

Some of the mice were allowed to sleep after they had learned to balance on the rod, others were not.

In the brains of those that had slept, there was more growth of dendritic spines.

In addition, the type of task the mice learnt –whether they ran forward or backward across the rod — affected where the dendritic spines grew.

Gan continued:

“Now we know that when we learn something new, a neuron will grow new connections on a specific branch.
Imagine a tree that grows leaves (spines) on one branch but not another branch. When we learn something new, it’s like we’re sprouting leaves on a specific branch.”

More on the science of sleep: Unwind: The Science of Rest, Relaxation and Sleep

Image credit: Ryan Ritchie

Children Suffer Mentally and Physically From Astounding Levels of Homework

“…students described the amount of homework each night as “overwhelming,” “unmanageable,” or “more than [they] could handle,””

According to new research, too much homework is associated with academic stress, a lack of balance in children’s lives and even physical health problems.

The new study into 4,317 students at 10 high-performing US high schools questions whether the average of 3 hours homework per night is really justified (Galloway et al., 2013).

The researchers asked students about the work they were doing and discovered that:

“Some of the students described the amount of homework each night as “overwhelming,” “unmanageable,” or “more than [they] could handle,” with one describing the load as “an endless barrage of work.””

One student wrote:

“There’s never a time to rest. There’s always something more you should be doing. If I go to bed before 1:30 I feel like I’m slacking off, or just screwing myself over for an even later night later in the week… There’s never a break. Never.”

The knock-on effects of all this homework were felt in both their sleep quality and their health:

“Many complained that the workload led to sleep deprivation and other health problems. Students described homework as the “main reason” preventing them from getting the recommended 9.25 hr of sleep each night.”

This feedback was supported by measures of the amount of homework students did and their well-being and engagement:

“Students who spent more hours on homework tended to be more behaviorally engaged in school, but were simultaneously more stressed about their school work and tended to reportmore physical symptoms due to stress, fewer hours of sleep on school nights, less ability to get enough sleep, and less ability to make time for friends and family.”

But surely all this homework is necessary and important?

Apparently not:

“…students will often do work they see as “pointless,” “useless,” and “mindless” because their grades will be affected if they do not. This kind of busy work, by its very nature, discourages learning and instead promotes doing homework simply to get points.”

All of this doesn’t mean homework should be banned, but 3 hours a night on average? Seriously?

The authors conclude by saying:

“Given the negative outcomes we find associated with more time spent on homework, our study calls into question the desirability of such diligence and the utility of assigning large quantities of homework in high-performing schools.
[…] any homework assigned should have a purpose and benefit, and it should be designed to cultivate learning and development.”

It seems the horrible, wasteful, idiotic culture of pointless ‘busywork’ is alive in well in some high schools.

→ Related: 10 Sleep Deprivation Effects.

Image credit: Vic Xia

Blue Light Can Improve Alertness and Attention Day or Night

Exposure to blue light can improve reaction times, attention and boost brain waves, according to a new study.

With so many people working indoors–and with natural light lacking in the winter months–a new study could have important implications for the design of artificial lighting (Rahman et al., 2014).

The research, conducted at Brigham and Women’s Hospital in Boston, exposed some participants to short-wavelength or blue light and others to green light. They carried on with their normal day-to-day activities under the light for 6.5 hours.

Afterwards those who’d been exposed to blue light had faster auditory reaction times, better attention and their brain wave patterns suggested they were more alert–although they didn’t consciously feel any more alert.

Shadab Rahman, the lead author, explained:

“Our previous research has shown that blue light is able to improve alertness during the night, but our new data demonstrates that these effects also extend to daytime light exposure. These findings demonstrate that prolonged blue light exposure during the day has an alerting effect.”

These findings come on top of findings from the same researchers that exposing people to blue light at night also increases alertness.

When people are illuminated with a blue light at night it brings their alertness up close to daytime levels.

Neuroscientist Steven Lockley, one of the study’s authors, said:

“These results contribute to our understanding of how light impacts the brain and open up a new range of possibilities for using light to improve human alertness, productivity and safety. While helping to improve alertness in night workers has obvious safety benefits, day shift workers may also benefit from better quality lighting that would not only help them see better but also make them more alert.”

It is hoped that smart lighting system which deliver the right wavelengths of light will be more widely available in the future.

Image credit: Joe St. Pierre

Patients in Vegetative State Can Respond Emotionally to Loved Ones

First study to demonstrate emotional awareness in patients in a persistent vegetative state.

It has long been thought that patients who are in a vegetative state–frequently due to a traumatic brain injury–have no awareness of their environment or themselves.

A new study using fMRI brain imaging, though, shows that some patients can display emotional reactions to pictures of loved ones (Sharon et al., 2013).

The study is surprising because patients in this condition show no signs of being aware of their surroundings. They breathe on their own, sleep and wake up, but otherwise appear utterly unresponsive to what’s going on around them.

Their families naturally wonder if they even realise they are there.

Responding to loved ones

The new study, though, put four patients who were in a persistent vegetative state (PVS) in a brain scanner and showed them pictures, some of people they knew and some of strangers.

These results were compared with those from a healthy control group.

For two PVS patients, the brain scans suggested emotional awareness.

One patient in particular–a 60-year-old woman who had been hit by a car–showed brain activity in the emotional and face-processing areas of the brain when looking at pictures of loved ones.

Similar activity was also seen when she was asked to imagine her parents’ faces.

The study’s first author, Dr. Haggai Sharon explained:

“This experiment, a first of its kind, demonstrates that some vegetative patients may not only possess emotional awareness of the environment but also experience emotional awareness driven by internal processes, such as images.”

The two patients who showed emotional awareness actually regained consciousness within two months of being tested. Neither remembered anything from when they were unconscious.

It’s possible the test may provide a clue about the patient’s prognosis and even point the way towards useful therapies for those in a persistent vegetative state.

Image credit: Anna Fischer

Why the Sleep-Deprived Crave Junk Food and Buy Higher Calorie Foods

A recent study has revealed exactly how a lack of sleep may lead to junk food cravings.

Recent studies reveal exactly how a lack of sleep may lead to junk food cravings.

Recent research from UC Berkeley scanned the brains of 24 participants after both a good, and a bad, night’s sleep (Greer et al., 2013).

After disturbed sleep, there was increased activity in the depths of the brain, which is generally associated with rewards and automatic behaviour.

The frontal lobes, just behind and above the eyes, which help provide self-control, were less active.

The finding may help explain why the sleep-deprived are more likely to give in to calorific temptations.

One of the study’s authors, Matthew Walker, explained:

“”What we have discovered is that high-level brain regions required for complex judgments and decisions become blunted by a lack of sleep, while more primal brain structures that control motivation and desire are amplified.”

In other words: lack of sleep robs people of their self-control and so their good intentions are quickly forgotten.

On top of this, the researchers found that after being deprived of sleep, participants displayed greater craving for high-calorie junk food. The more sleep-deprived they were, the greater the cravings.

By contrast, when they were well rested, the same people were better able to resist temptation.

Bring me burgers!

This study is the latest in a wave of recent research examining the link between lack of sleep and poor dietary choices.

A study of 13,284 teenagers found that those who slept poorly also made poor decisions about food.
Similarly, a Swedish study found that at a buffet, tired people were more likely to load up their plates (Hogenkamp et al., 2013).

The link has even been made from poor sleep through to food shopping.

A Swedish study found that men who were sleep-deprived bought, on average, 9% more calories than those who’d had a good night’s sleep (Chapman et al., 2013). These results were likely the result of the poor decision-making identified by the UC Berkeley study.

It had been thought that the tendency to eat more after poor sleep was related to the so-called ‘hunger hormone’ ghrelin. But the latest studies suggest that it’s simple self-control that is most important in causing the sleep-deprived to over-indulge.

Dr Lauren Hale, author of the study of teenagers, said:

“If we determine that there is a causal link between chronic sleep and poor dietary choices, then we need to start thinking about how to more actively incorporate sleep hygiene education into obesity prevention and health promotion interventions.”

To find out more about sleep hygiene, check out: How To Fall Asleep Fast.

Also here are 10 sleep deprivation effects.

Image credit: Josh Janssen

Offline Learning: How The Mind Learns During Sleep

A nap as short as 6 minutes after learning can help to consolidate learning and improve performance.

It’s been more than a century since the first scientific evidence was produced that sleep benefits memory.

But the man who stumbled on it, German psychologist Hermann Ebbinghaus, couldn’t believe that learning during sleep could explain anomalies in his results, and he rejected the possibility.

It wasn’t until forty years later that the power of ‘the sleep effect’ was demonstrated directly (Jenkins & Dallenbach, 1924).

Since then, studies have been carried out to find out what types of memory are affected by sleep, how much sleep is required and how the effect occurs.

For example, people have asked: is it just memory for facts, or does it also work for physical movements?

The interest in the effect is hardly surprising: the idea that you can learn while unconscious is one more beautiful thing about sleep.

Learn while you sleep

Here’s a recent example of a typical study investigating the effect.

Payne et al (2012) had people learn a series of word-pairs, like RIDER and SWITCH, either at 9am in the morning or 9pm at night.

There were then tested at 30 minutes after learning, 12 hours later and 24 hours later.

The results showed that whether they learned in the morning or evening, it made little difference to their recall just 30 minutes later.

But, over a longer delay, differences did emerge.

The people who had learned the word-pairs before bed performed better than those that had learned them in the morning.

These are not isolated results. Fenn and Hambrick (2012) carried out a similar study and got the same result: people who learned before they slept did better than those who followed the learning with a period of wakefulness.

These researchers also found that some people, those with a better ‘working memory’, were particularly good at learning while they slept.

Six-minute benefit

There is now all sorts of research showing that different types of learning are improved by a subsequent period of sleep.

For example, procedural learning–like that involved in playing tennis or learning fingering on the piano–is improved by subsequent periods of sleep.

Similarly, perceptual learning–like being able to distinguish two notes from each other–has also shown improvements from subsequent periods of sleep.

Researchers then wondered how short the sleep can be to see the benefits.

It turns out that you’re better off to learn new information before your full eight hours. But benefits to learning have been shown in one study for a nap as short as six minutes (Lahl, 2008).

Learning offline

Scientists aren’t exactly sure why learning benefits from sleep. The old theory used to be that everyday events interfered with newly learned memories causing them to fade away or get muddled. In other words, sleep was better after learning because no new memories could interfere.

Now, though, many psychologists believe that there is an active process at work while we sleep.

During the unconscious period, our minds may be working on the memories and more strongly encoding them for later retrieval.

This may be part of the reason why, like many others, John Steinbeck pointed out:

“It is a common experience that a problem difficult at night is resolved in the morning after the committee of sleep has worked on it.”

Image credit: Toni Blay