The age at which sleep has the greatest influence on cognitive function.
The time of life when sleep has the greatest influence on cognitive function.
Good sleep in young and middle-aged people helps boost memory up to 28 years later, a new review of the evidence finds.
However, people in their 70s, 80s and 90s do not typically sleep so well and the link to a good memory is less strong.
Dr Michael K. Scullin, who co-authored the review of around 2,000 separate studies, said:
“If sleep benefits memory and thinking in young adults but is changed in quantity and quality with age, then the question is whether improving sleep might delay — or reverse — age-related changes in memory and thinking.
It’s the difference between investing up front rather than trying to compensate later.
We came across studies that showed that sleeping well in middle age predicted better mental functioning 28 years later.”
Deep sleep in particular has a whole host of mental benefits, found the 50-year review of research which is published in the journal Perspectives on Psychological Science (Scullin & Bliwise, 2015).
Just one of those is that during this time memory is sorted and consolidated for better recall later on.
Even sleep during the day, in the form of an afternoon nap, can be beneficial for memory, as long as sleep at night is still sufficient.
Later in life, though, people tend to sleep worse, with less deep sleep and more wakefulness during the night.
Dr Scullin says:
“…even if the link between sleep and memory lessens with age, sleeping well is still linked to better mental health, improved cardiovascular health and fewer, less severe disorders and diseases of many kinds.”
Poor sleep’s negative effect on memory is well-known, but what about the effect of memory on sleep?
Poor sleep’s negative effect on memory is well-known, but what about the effect of memory on sleep?
It’s long been known that animals — from flies to humans — have trouble with their memory when they don’t get enough sleep.
Getting enough sleep is critical in converting short-term memories into long-term memories.
That’s the reason that all-nighters don’t work; but little is known about how memory affects sleep.
One theory has it that memory neurons are actively trying to put us to sleep so our brains can transfer information into long-term memory.
In a new study, researchers at Brandeis University have put this to the test in fruit flies.
The fly has a structure in its brain called ‘the mushroom body’, which is similar to the hippocampus, the area of the human brain that’s vital for memory consolidation.
The results, published in the journal eLife, show for the first time that when critical memory neurons were active, the flies slept more (Haynes et al., 2015).
This suggests that memory plays an active role in the sleep cycle.
Not only did parts of the mushroom body in the fly’s brain help send it to sleep, at other times it was helping to keep it awake.
Bethany L Christmann, one of the study’s authors explains:
“It’s almost as if that section of the mushroom body were saying ‘hey, stay awake and learn this.’
Then, after a while, the DPM neurons start signaling to suppress that section, as if to say ‘you’re going to need sleep if you want to remember this later.'”
Christmann continued:
“Knowing that sleep and memory overlap in the fly brain can allow researchers to narrow their search in humans.
Eventually, it could help us figure out how sleep or memory is affected when things go wrong, as in the case of insomnia or memory disorders.”
Study finds that these devices damage people’s sleep and may worsen their health.
Study finds that these devices damage people’s sleep and may worsen their health.
Using e-readers, like an iPad, that emit blue light can disrupt both sleep and general health if read before bedtime, a new study concludes.
Researchers at Brigham and Women’s Hospital compared the effects of reading an iPad in the hours before sleep with reading a traditional paper book.
Dr. Anne-Marie Chang, the study’s first author, explained the results:
“We found the body’s natural circadian rhythms were interrupted by the short-wavelength enriched light, otherwise known as blue light, from these electronic devices.
Participants reading an LE-eBook took longer to fall asleep and had reduced evening sleepiness, reduced melatonin secretion, later timing of their circadian clock and reduced next-morning alertness than when reading a printed book.”
In the two-week long study, published in the Proceedings of the National Academy of Sciences, 12 people read an iPad or a printed book for four hours before bedtime over five consecutive nights (Chang et al., 2014).
When people read the iPad they felt less sleepy in the evening, spent less time in rejuvenating REM sleep and their bodies produced less of the sleep-inducing hormone melatonin.
After eight hours sleep, the iPad readers were less alert and felt sleepier.
The results are likely not specific to the iPad, but apply to any devices which emit blue light, like LED monitors, cell phones and laptops.
E-readers such as the original Kindle, which does not emit light, are probably fine.
Professor Charles Czeisler, a distinguished sleep researcher and one of the study’s authors, said:
“In the past 50 years, there has been a decline in average sleep duration and quality.
Since more people are choosing electronic devices for reading, communication and entertainment, particularly children and adolescents who already experience significant sleep loss, epidemiological research evaluating the long-term consequences of these devices on health and safety is urgently needed.”
2. Why some people only need five hours’ sleep a night
While most people can get by with less than six hours sleep, the majority will suffer physically and psychologically, especially if sleep deprived over the long-term.
However, a gene mutation which means a person can function normally with only five hours’ sleep a night has been identified by a new study of 100 pairs of twins.
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 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.
Just believing that you’ve slept better than you really have is enough to boost cognitive performance the next day.
The findings comes from a study of 164 people who were given a lecture on how important sleep quality is and told they would be given a new test of how well they had slept the previous night.
After the test, some were told they’d slept well the previous night, others that they’d slept badly.
This had no relationship to how they had actually slept and were just made up to try and convince one group they’d slept better than the other.
Those told they’d slept better scored higher on tests of attention and memory than those told they’d slept poorly.
How you slept last night isn’t just about how you actually slept, it’s also about how you think you slept.
This study suggests that tweaking your mindset a little could be enough to boost your performance.
Failing to get enough sleep causes low mood in teenagers, along with worse health and poor learning.
But it’s not all down to late night video gaming or TV: the part of the brain which regulates the sleep-wake cycle — the Suprachiasmatic Nucleus — changes in puberty.
Teenage brains also secrete less melatonin so their ‘sleep drive’ reduces.
As a result, being forced to rise the next day at 6am for school or college means teens find it hard to get the 8 to 10 hours sleep that they need.
Although hormonal changes are partly to blame for teenage angst, being short of sleep significantly contributes to lack of motivation and poor mood.
We all know that lack of sleep affects our memory, along with other cognitive abilities.
But now new research shows that not getting enough sleep increases the chances your mind will actually create false memories.
In the study, one group of participants were allowed to get a full nights’ sleep, while another had to stay up all night.
In the morning they were given a load of information about a crime — some true, some false — that had been committed.
The results showed that those who’d missed out on their sleep were the most likely to regurgitate the false information, 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.
A new study has found evidence for a long-suspected danger of sleeping pills: an increased risk of death.
The large study looked at data from over 100,000 patients who had been to their family doctors across seven years.
It found that taking sleeping pills, like zolpidem/Ambien, doubled the risk of death.
Professor Scott Weich, who led the study, said:
“That’s not to say that they cannot be effective.
But particularly due to their addictive potential we need to make sure that we help patients to spend as little time on them as possible and that we consider other options, such as cognitive behavioural therapy, to help them to overcome anxiety or sleep problems.”
9. Sleep drunkenness disorder affects one in seven
As many as one in seven people may be affected by ‘sleep drunkenness disorder’ soon after they’ve woken up or during the morning.
Sleep drunkenness disorder involves severe confusion upon wakening — way more than just the usual morning grogginess — and/or inappropriate behaviour: things like answering the phone instead of turning off the alarm.
Confused awakenings can happen to people when very short of sleep or jet-lagged, but are regular occurrences for those with the disorder.
Researchers have found that 15% of people had experienced at least one episode of sleep drunkenness in the last year.
People who realise they are in a dream while they are dreaming — a lucid dream — have better problem-solving abilities, new research finds.
This may be because the ability to step outside a dream after noticing it doesn’t make sense reflects a higher level of insight.
Around 82% of people are thought to have experienced a lucid dream in their life, while the number experiencing a lucid dream at least once a month may be as high as 37%.
Dr Patrick Bourke, who led the study, said:
“It is believed that for dreamers to become lucid while asleep, they must see past the overwhelming reality of their dream state, and recognise that they are dreaming.
The same cognitive ability was found to be demonstrated while awake by a person’s ability to think in a different way when it comes to solving problems.”
New sleep centre discovered and neuroscientists succeed in turning it on and off using a virus.
New sleep centre discovered and neuroscientists succeed in turning it on and off using a virus.
A circuit in the brain that promotes deep sleep, which reinvigorates the brain from its daily activities, has been identified for the first time by neuroscientists using an innovative new method.
The ‘sleep-node’ — the second to be discovered — lies deep in the ancient part of the brain and is vital in sending us off into a ‘slow-wave’ or deep sleep, which is one of the stages of sleep we cycle through during the night.
The area is in the parafacial zone (PZ) in the brain stem, and it produces half of all the brain’s sleep-promoting activity.
The brain stem controls our most basic functions like breathing, heart rate, blood pressure, temperature — and sleep.
Neuroscientists used a sophisticated new approach to turn this region of the brain on and off in mice (Anaclet et al., 2014).
Patrick Fuller, one of the study’s authors, explains:
“To get the precision required for these experiments, we introduced a virus into the PZ [parafacial zone] that expressed a ‘designer’ receptor on GABA neurons only but didn’t otherwise alter brain function.
When we turned on the GABA neurons in the PZ, the animals quickly fell into a deep sleep without the use of sedatives or sleep aids.”
How the parafacial zone in the brain stem interacts with other areas of the brain is not yet known, but this is an important new tool in investigating the function of different areas of the brain.
Christelle Ancelet, another of the study’s authors, said:
“These new molecular approaches allow unprecedented control over brain function at the cellular level.
Before these tools were developed, we often used ‘electrical stimulation’ to activate a region, but the problem is that doing so stimulates everything the electrode touches and even surrounding areas it didn’t.
It was a sledgehammer approach, when what we needed was a scalpel.”
Caroline E. Bass, another of the study’s authors, commented:
“We are at a truly transformative point in neuroscience, where the use of designer genes gives us unprecedented ability to control the brain.
We can now answer fundamental questions of brain function, which have traditionally been beyond our reach, including the ‘why’ of sleep, one of the more enduring mysteries in the neurosciences.”
The scientists hope the findings will eventually lead to new treatments for sleep disorders like insomnia.
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.
This research could lead to a cure for jet-lag and other sleep problems.
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.
Short of sleep? Your memory could be playing serious tricks on you.
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.
Four 10 to 15 minute sleep interruptions in the night enough to leave people groggy and grumpy.
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.”
The physical changes in the motor cortex that result from learning and sleep.
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.”
