ALZHEIMER

Alzheimer's link to copper-rich food

http://www.express.co.uk/news/health/423301/Alzheimer-s-link-to-copper-rich-food

A DIET packed with copper-rich foods – from red meat to shellfish – could trigger Alzheimer’s, warn scientists.

New research reveals the metal appears to be a key factor in the onset and development of dementia.

It can prevent toxic proteins clearing in the brain and speed up their accumulation.

Lead researcher Dr Rashid Deane said: “It is clear that these effects are due to exposure over a long period of time.

“The key will be striking the right balance between too little and too much copper consumption.

“Right now, we cannot say what the right level will be, but diet may ultimately play an important role.”

Copper is also found in water, vitamin and mineral supplements, nuts, fruit and vegetables. It is vital to nerve conduction, hormone secretion and the growth of bone and connective tissue.

But the new study, using mice and human cells, shows that copper can also accumulate in the brain and cause the blood-brain barrier to break down. This results in accumulation of the protein amyloid beta, a hallmark of Alzheimer’s.

The US University of Rochester Medical Center study is published in Proceedings of the National Academy of Sciences.

Experts discover 11 new ‘risk genes’ for Alzheimer’s Disease

http://www.express.co.uk/news/health/439601/Experts-discover-11-new-risk-genes-for-Alzheimer-s-Disease

A MAJOR breakthrough in Alzheimer’s research could pave the way for early detection and new treatments.

By: Jo Willey

A landmark study, the largest of its kind, has identified 11 new risk genes linked to the deadly brain disease.

A number of these genes impact on the immune system, which researchers now know plays a crucial role in the development of Alzheimer’s.

Professor Julie Williams, head of neurodegeneration at the Cardiff ­University School of Medicine’s ­Medical Research Council Centre on Neuropsychiatric Genetics and Genomics, led one of four global research teams.

She said: “Now we know a lot more about what is causing the disease, but we need to know more about the how. How these genes are actually contributing to the disease’s process and then we get to target errors with drugs or other interventions.

“Several of us will have some risk factors for many diseases, but it is having a number of them that will push us over the edge to developing them.

“I think the more genes we find, the more we can use that information to identify people before they develop it or people who are in the early stages of the disease.”

The UK scientists joined forces in an international collaboration to gather data from 74,046 individuals to pinpoint 11 Alzheimer’s risk genes.

This builds on their previous work from 2009, which identified 10 genes known to be associated with Alzheimer’s, taking the total to 21.

Professor Williams said: “By combining the expertise and resources of geneticists across the globe, we have been able to overcome our natural competitive instincts to achieve a real breakthrough in identifying the genetic architecture that significantly contributes to our mapping of the ­disease.” One of the most significant discoveries of the research, which is published in the journal Nature Genetics, was found in a region of a brain that confirms the involvement of the immune system in the disease.

Professor Hugh Perry, chairman of neurosciences and the Mental Health Board at the Medical Research ­Council, said: “It is particularly noteworthy that this study yet further strengthens the role of the immune response in the development of ­Alzheimer’s.”

Dr Eric Karran, of Alzheimer’s Research UK, said: “Alzheimer’s is a complex disease that requires a multi-faceted research approach and this important study shows the progress that can come through collaboration.

“Alzheimer’s Research UK is pleased to be supporting scientists at the ­cutting edge of this progress.

“While this new discovery holds real potential, the true value will come from pinpointing the exact genes involved, how they contribute to Alzheimer’s, and how this could be translated.”

New hope in Alzheimer’s treatment

http://www.express.co.uk/news/health/430784/New-hope-in-Alzheimer-s-treatment

By: Jo Wiley

DRUGS for the treatment of Alzheimer’s disease before it even develops are being tested on patients for the first time.

Scientists are conducting a clinical trial into two new medications to see whether giving them to patients early can stop the disease before any symptoms show.

The treatments are both antibodies, gantenerumab and solanezumab, and work by removing the rogue toxic protein known as beta amyloid.

These form destructive plaques which destroy the brain and lead to memory loss and eventually death.

Many experts are now convinced that the way to beat Alzheimer’s is to stop this trail of destruction in its tracks before it has time to develop.

The trial is led by Prof Randall Bateman, a neurologist at the University of Washington.

Prof Bateman said: “We believe the diverse portfolio of drugs and approaches of the trial will accelerate the discovery of an effective treatment for Alzheimer’s.”

http://mag.newsweek.com/2013/10/25/sleep-science-brain.html

CLEARING YOUR BRAIN'S CACHE

Scientist may have finally figured out why we sleep, and the answer could help beat Alzheimer's

By  Chris Weller, Elijah Wolfson

Each night, most of us willingly, eagerly slide into a near-death state. Okay, call it sleep. But just because it happens all the time, doesn't mean it's not strange, even dangerous. It seems like pretty bad evolutionary design to have to be defenseless for a good chunk of your lifetime, but evolution usually doesn't get things wrong.

We know sleep is important - dolphins have developed a system in which only half their brains sleep at a given time to ensure both safety and sufficient zzz's - but we don't know why. For years, researchers and philosophers have wrestled with this question, coming up with theories ranging from the adaptive (we sleep so saber-toothed tigers don't eat us while we stumble around blindly at night) to the restorative (we sleep so our bodies can replenish all the stuff it used up during the day). Alas, these notions, while compelling, don't match what happens in the brain during sleep.

The mystery may be solved. A recent study finally reveals the science behind why we sleep, and it has experts dusting off words like "landmark" and "game-changing."

The story begins in the daytime. Your daily experiences - living, essentially - put your brain under enormous stress. It must absorb, interpret, analyze, itemize, concretize, and process all the data pummeling it. Tough job. Big job. Important job. And since all of that information must get cataloged, the brain needs a way to keep the important parts and get rid of what's unnecessary. Researchers from the University of Rochester Medical Center suggest sleep may serve that function.

Led by URMC postdoctoral fellow Dr. Lulu Xie, the research team injected dye into the cerebrospinal fluid (CSF) of lab mice to see how fast the dye moved through the fluid both when the mice were in conscious and unconscious states. The results were astounding. Brain activity in the sleeping mice was diminished (no surprise), but so was the dye's transportation through the CSF. The dye had a harder time making it through the fluid of unconscious mice than through that of the waking mice, whose CSF offered a clear pathway around the brain tissue.

Of course, we humans don't have dye coursing through our brains. We have a substance far more sinister: amyloid plaques, proteins that build up over time and that, for years, have been the prime suspect for what causes Alzheimer's. Beta-amyloid plaques must be removed from the brain, or they gradually clog healthy pathways, degrade the neural connections within the brain and collapse the neuron's transport system. Scientists now believe sleep is the only way to adequately fight beta-amyloid buildup.

"When you're awake, it's like all the streets of Manhattan being clogged with vehicles, as they are during the daytime," says Dr. Charles Czeisler, director of the Division of Sleep Medicine at Harvard University Medical School. "The garbage trucks cannot clear the garbage efficiently. And what they've shown in this study is that those 'garbage trucks' can only clear about 5 percent as efficiently as they can clear during sleep."

In other words, sleep is when your brain takes out the trash.

"The brain has limited energy at its disposal, and it appears that it must choose between two different functional states - awake and aware, or asleep and cleaning up," Dr. Maiken Nedergaard, the study's lead author, said in a statement. "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."

Unlike the rest of the body, which uses the lymphatic system to help cycle and flush various fluids and fatty acids from tissues and areas of the digestive system, the brain has its own ecosystem. Scientists call it the glymphatic system, and it relies on brain cells, called glia, shrinking in size to allow the CSF to more easily pass through it. In Czeisler's metaphor, the glymphatic system is what allows the traffic to disperse, clearing the way for garbage trucks to rumble through. But because of the blood-brain barrier, the fluid needs a way to move through to the rest of the body, so it piggybacks on surrounding blood vessels and circulates throughout the body, ultimately finding its way to the liver, where it will be removed as waste.

This outlines sleep's basic role, but it also illuminates a more pressing question, namely: Does less sleep raise a person's risk for cognitive decline?

Czeisler says it does: "We know that these by-products, like many metabolic by-products from burning energy, are toxic. The by-products produced when neurons burn energy are toxic to those neurons and they have to be cleared out, and they are cleared out 20 times more efficiently during sleep. We've known for years that patients with Alzheimer's disease have disturbed sleep. And this article, for the first time, suggests that this could be part of the causal pathway."

Many experts have already declared this finding to be groundbreaking, and it could be the start of a revolution in brain science. "When I say 'landmark,' " Czeisler says of this research, "I'm presuming that it is replicated - and not just replicable in a rat. If it turns out to be true across animal species, then it would have revealed the fundamental functions of sleep."

8 Habits Of Extremely Well-Rested People

http://www.huffingtonpost.com/2013/10/23/sleep-habits_n_4145681.html
 By Laura Schocker

Most of us have probably met (and envied) at least one of those mysterious people who never seem to be tired. We've sized them up through bleary eyes, and wondered how it is that they don't look like they spent 30 minutes battling with the snooze button this morning. The answer isn't necessarily that they have the luxury of more hours to sleep; instead, many of the most well-rested have some simple habits that help them achieve plenty of high-quality rest.

One thing they often have in common? Discipline. The body likes routine, which allows your natural circadian rhythms to kick in. And while it can be tempting to answer one more email or stay for one last round of drinks, well-rested people prioritize sleep the same way they know to do for diet and exercise. "It's maintaining a regimented sleep/wake cycle and protecting one's sleep," says Michael Decker, Ph.D., a sleep specialist and associate professor at Case Western School of Nursing.

Decker and Joe Ojile, M.D., founder and CEO of the Clayton Sleep Institute in St. Louis, Mo., shared some of the most common traits among the bright-eyed and bushy-tailed.

They don't sleep in

People often obsess about bedtimes, but one of the most important things in establishing a healthy sleep pattern is sticking to a regular wake time (and seeking bright light first thing in the morning). A steady wake up call sets your circadian rhythms, or internal clock, helping you to feel tired at the right time in the evening. "When you need to go to bed at night is, to a large degree, determined by when you get up and when you get light in the morning," Ojile says. "Even some nights if you can't get to bed on time, you should get up at your approximately same wake time."

And, sorry weekend binge sleepers, but that includes Saturdays and Sundays. Dramatically altering your sleep and wake times on your days off can throw your body clock out of whack, a phenomenon experts call "social jet lag." You might live in New York, but by Monday morning your body feels like it's traveled to California and back, disrupting your rhythms and setting you up for a week of bad sleep -- one you'll try to compensate for by oversleeping the next weekend, perpetuating a vicious cycle. (On top of that, research suggests "recovery sleep" might not be doing your brain any good.)

The good news? Getting the right amount of sleep all week means you won't need to play catch up on the weekends. "You've already, in effect, paid the sleep piper throughout the week," Ojile says. "It's almost like a bill you have to pay every day. People who don't have to pay down their sleep debt over the weekend have all that time to do other healthy behaviors."

They check electronics at the bedroom door

Almost everyone -- 95 percent of Americans, according to the National Sleep Foundation's 2011 Sleep in America Poll -- uses some sort of electronic device in the hour before bed, and, according to a recent HuffPost/YouGov poll, 63 percent of smartphone owners between the ages of 18 to 29 cop to falling asleep with their cell phone, smartphone or tablet in bed. But all that nighttime screen-time might be messing with our shuteye: Not only do 3 a.m. texts disrupt sleep, but our many gadgets -- TVs, laptops, tablets or smartphones -- emit light that can signal to the brain that it's daytime, or time to be awake.

"Artificial light exposure between dusk and the time we go to bed at night suppresses release of the sleep-promoting hormone melatonin, enhances alertness and shifts circadian rhythms to a later hour -- making it more difficult to fall asleep," Charles Czeisler, Ph.D., M.D., of Harvard Medical School, said in a statement when the National Sleep Foundation's results were released.

On top of disruptive light, reserving the bed for sleep (and sex) helps the brain to associate hitting the mattress with going to sleep, something experts call a "stimulus response relationship," Ojile explains. When your bed doubles as a home office, on the other hand, the brain thinks of it as a place to think and ruminate, neither of which are conducive to drifting off. There are ways to set up your bedroom for sleep success,but they certainly don't involve anything with a power button.

They nap strategically

Well-rested people know the value of a good nap. Done correctly, a midday snooze can optimize alertness, productivity and creativity, and reduce stress. If you weren't able to achieve your optimal number of hours the night before, or if you're just dragging, a short nap can be exactly what your body needs to reboot.

Ojile recommends capping your siesta at 30 minutes or so -- any longer than that and your body will move into the phases of deep sleep, leaving you groggier than when you started. The best time to nap is often between 2 and 3 p.m., when you have a natural biological dip. Catnapping too late in the afternoon or evening, though, can leave you tossing and turning long past bedtime, so don't fall asleep after 4 p.m. And it's important to note that insomniacs who have trouble falling sleeping at night or staying asleep should typically skip naps altogether.

They move

Good sleep isn't just about what happens when you're lying down. People who engage in physical activity typically sleep better than those who don't. In fact, according to the National Sleep Foundation's Sleep in America poll, exercisers report better quality sleep than their sedentary peers -- more than 80 percent of those who categorized themselves as vigorous exercisers reported having fairly good or very good sleep quality, compared to just 56 percent of those who said they didn't get any activity. Even a little movement helps: 76 percent of those who fit into the "light" exercise category reported fairly good or very good sleep quality. "Active just means getting up off the couch and doing something, it doesn't mean you have to be a marathon runner," Ojile says.

While typical sleep hygiene advice often includes not exercising too late at night, the poll actually found that people who exercised close to bedtime didn't report a difference in snooze quality compared to those who worked out earlier in the day. What to make of that? Ojile says if you're someone who can work out in the evening without it keeping you up, go for it. If it's problematic, move up your sweat session.

They think about sleep before sleeping

"You'd never work out without stretching first would you?" Decker says. "And sleep is the same way in that we need to go through a process to prepare ourselves."

It can be difficult for many people to go from 60 to 0 after a jam packed day. (If only we had "off" buttons!). About an hour or so before bed, it's important to prepare your body to sleep by powering down electronics and swapping them out for more soothing activities, such as reading a book or taking a bath. Eventually, a regular nighttime routine can automatically send signals to the body that it's time to sleep.

They eat and drink the right stuff, at the right time

By now, we all know to switch to decaf in the afternoon to avoid counting sheep way past midnight. But other evening diet choices could be unwittingly keeping you awake, including chocolate, a big steak or even spicy foods. On top of that, eating a big meal late at night can stimulate your metabolism to start working on overdrive, Decker explains, and as your metabolism wakes up, you do too. "Those people who are well-rested, their dietary choices prevent caffeinated drinks [and heavy dinners] at night," he says.

They pass on alcohol too. While that nightcap might help you drift off initially,researchers have linked it to disrupted sleep later in the night.

They appreciate the value of sleep

Trying to push through the wee hours of the night on next to no sleep is a recipe for burnout, not productivity. Well-rested people don't resent the need to sleep, and instead accept it as an important key to optimal health and performance. "Look at sleep as a health-giving enterprise," Ojile says. "It's giving [people] all this great stuff effectively for free. It's the most cost effective health program there is."

Still not convinced? Consider this: sleep deprivation has been linked with a whole host of serious health issues, including increased stroke risk, obesity and memory loss.

But they don't obsess about it

On the flip side, worrying about drifting off is counterproductive, as anxiety and sleep don't mix. HuffPost blogger Christopher Winter explained in a blog post last year:

The simple answer is often the individual who can't sleep is anxious about not sleeping. People fear many things: flying, heights, drowning, blood and bodily injuries, even death. Being awake is not a common fear. Most of us greatly enjoy being awake. Being awake is usually viewed as a good thing, just not when we are trying to sleep. When we are awake during a time we want to sleep, we get upset. We also get anxious about the consequences of not getting a good night's sleep and the impact it may have on the next day. So, by addressing this anxious reaction to not sleeping, we can prevent individuals from developing this circular response (can't sleep, anxious about not sleeping, even less likely to sleep, more anxious about not sleeping, repeat) and thus facilitate sleep.

Having one night of bad sleep? Instead of worrying about it, get up out of bed and do something relaxing until you feel tired.

Thousands with tuberculosis not given treatment to stay alive, warns WHO

http://www.theguardian.com/global-development/2013/oct/23/tuberculosis-treatment-global-who
Sarah Boseley
Global failure to tackle multidrug-resistant tuberculosis costing lives, say experts, as three in four cases go undiagnosed

Approximately 16,000 people were diagnosed with multidrug-resistanttuberculosis in 2012 but were not given the treatment they needed to stay alive and prevent the spread of the disease, the World Health Organisation (WHO) has said.

While there has been some progress – with a drop in cases to 8.6m in 2012, from 8.7m in 2011, and in deaths from 1.4m in 2011 to 1.3m in 2012 – a report by the WHO says there are serious concerns about the estimated 3 million people with TB who are not receiving treatment because they live in remote rural areas, and about the spread of drug-resistant strains.

The director of its TB programme, Dr Mario Raviglione, warned on Wednesday of a public health crisis, while Médecins Sans Frontières (MSF), the international medical organisation, described the figures as shocking.

As the problem of MDR-TB grows, so do the waiting lists for the expensive and lengthy courses of treatment – it can take two years to cure somebody. Many countries are not getting high cure rates as a result.

"The unmet demand for a full-scale and quality response to multidrug-resistant tuberculosis is a real public health crisis," says Raviglione. "It is unacceptable that increased access to diagnosis is not being matched by increased access to MDR-TB care. We have patients diagnosed but not enough drug supplies or trained people to treat them. The alert on antimicrobial resistance has been sounded; now is the time to act to halt drug-resistant TB."

An estimated 450,000 people contracted MDR-TB in 2012, the WHO says. The largest numbers were in China, India and Russia, but three in four estimated cases remained undiagnosed.

Dr Philipp Du Cros, infectious disease specialist at MSF, said: "These shocking figures are an indictment of the global failure to tackle drug-resistant tuberculosis head-on. People are paying for this failure with their lives … Unless we take urgent action, we will continue to see an increase in harder-to-treat drug-resistant strains of TB."

He called for more resources and better drugs to tackle the crisis. "To save lives, we urgently need governments, donors, and the Global Fund to properly resource the treatment of this deadly disease. We urgently need more research to make treatments for TB shorter, more effective and less damaging for patients. Patients with drug-resistant TB currently face an agonising two-year ordeal, taking large quantities of very harsh drugs with horrific side effects. Even then, it's only a flip of a coin chance that treatment will be successful."

The report calls for drug-resistant TB to be considered a public health crisis."In high MDR-TB burden countries, increased capacity to diagnose MDR-TB must be matched with supplies of quality drugs and scaled-up country capacity to deliver effective treatment and care," it says. "This will require high-level political will and leadership and more collaboration among partners, including drug regulatory authorities, donor and technical agencies, civil society and the pharmaceutical industry."

The 3 million missed cases must be reached, the WHO says. People who are HIV positive and have TB must be given antiretroviral drug treatment. The funding gap must be closed – an extra $2bn a year is needed on top of the $6bn made available for TB in 2013. "Progress remains fragile and could be reversed without adequate funding," the report warns.

on SLEEP

http://www.bbc.co.uk/news/health-24567412
James Gallagher

The brain uses sleep to wash away the waste toxins built up during a hard day's thinking, researchers have shown.

The US team believe the "waste removal system" is one of the fundamental reasons for sleep.

Their study, in the journal Science, showed brain cells shrink during sleep to open up the gaps between neurons and allow fluid to wash the brain clean.

They also suggest that failing to clear away some toxic proteins may play a role in brain disorders.

One big question for sleep researchers is why do animals sleep at all when it leaves them vulnerable to predators?

It has been shown to have a big role in the fixing of memories in the brain and learning, but a team at the University of Rochester Medical Centre believe that "housework" may be one of the primary reasons for sleep.

"The brain only has limited energy at its disposal and it appears that it must choose between two different functional states - awake and aware or asleep and cleaning up," said researcher Dr Maiken Nedergaard.

"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."

Plumbing

Their findings build on last year's discovery of the brain's own network of plumbing pipes - known as the glymphatic system - which carry waste material out of the brain.

Scientists, who imaged the brains of mice, showed that the glymphatic system became 10-times more active when the mice were asleep.

Cells in the brain, probably the glial cells which keep nerve cells alive, shrink during sleep. This increases the size of the interstitial space, the gaps between brain tissue, allowing more fluid to be pumped in and wash the toxins away.

Dr Nedergaard said this was a "vital" function for staying alive, but did not appear to be possible while the mind was awake.

She told the BBC: "This is purely speculation, but it looks like the brain is losing a lot of energy when pumping water across the brain and that is probably incompatible with processing information."

She added that the true significance of the findings would be known only after human studies, but doing similar experiments in an MRI machine would be relatively easy.

Commenting on the research Dr Neil Stanley, an independent sleep expert, said: "This is a very interesting study that shows sleep is essential downtime to do some housekeeping to flush out neurotoxins.

"There is good data on memory and learning, the psychological reason for sleep. But this is the actual physical and chemical reason for sleep, something is happening which is important."

Dr Raphaelle Winsky-Sommerer, a lecturer in sleep at Surrey University, said: "It's not surprising, our whole physiology is changing during sleep.

"The novelty is the role of the interstitial space, but I think it's an added piece of the puzzle not the whole mechanism.

"The significance is that, yet again, it shows sleep may contribute to the restoration of brain cell function and may have protective effects."

Many conditions which lead to the loss of brain cells such as Alzheimer's or Parkinson's disease are characterised by the build-up of damaged proteins in the brain.

The researchers suggest that problems with the brain's cleaning mechanism may contribute to such diseases, but caution more research is needed.

The charity Alzheimer's Research UK said more research would be needed to see whether damage to the brain's waste clearance system could lead to diseases like dementia, but the findings offered a "potential new avenue for investigation".

Boosting sleep 'may slow memory rot'

http://www.bbc.co.uk/news/health-21199949

 James Gallagher

It may be possible to slow the decline in memory and learning as we age by tackling poor sleep, researchers hope.

Their study, in the journal Nature Neuroscience, has revealed an intimate relationship between an ageing brain, sleep and memory.

Experiments showed that changes in the ageing brain damaged the quality of deep sleep, this in turn hampered the ability to store memories.

Scientists want to test ways of boosting sleep to halt memory decline.

Wisdom may come with age, but both the brain and the body take the strain of time. Many people will be aware that both their memory and sleep are not as good as in their earlier years.

Researchers at the University of California, Berkeley, said it was unknown whether changes in the brain, sleep and memory were all separate signs of ageing or deeply connected.

A good kip

They performed a series of experiments on 36 people - an even split of those in their twenties and their seventies.

First the team showed that they could use the state of a region of the brain, called the medial prefronal cortex, to predict how much deep, or slow-wave, sleep a person would have.

That part of the brain is essential for entering deep sleep, but with age the region degrades.

Secondly, they showed that the amount of deep sleep could be used to predict how well people would do on memory tests.

The younger patients getting loads of good quality sleep performed better on tests than their older colleagues who had worse quality sleep.

One of the researchers, Dr Matthew Walker told the BBC: "Taken all together, the deterioration of the brain leads to the deterioration of sleep to the deterioration of memory."

"Slow wave sleep is critically important for cementing new memories you've recently learned. It's like clicking the save button.

"It's especially depressing as I continue to get older, but there might be a silver lining."

Researchers are not able to restore the ageing section of the brain, but they believe they can do something about sleep.

It is possible to boost the quality of sleep by stimulating the right region of the brain with electricity during the night.

The researchers said this had been shown to boost memory performance in young people and they wanted to begin experiments on elderly patients too.

"You don't have to restore brain cells to restore sleep," said Dr Walker who described their aim as "jump-starting" the system.

Dementia

In patients with dementia, the symptoms of brain cells dying, bad sleep and memory loss are far far worse than in normal ageing.

Some studies have suggested a link between and dementia. A report,published in the journal Science Translational Medicine, suggested problems sleeping may be an early sign of Alzheimer's.

Dr Simon Ridley, from the charity Alzheimer's Research UK, said further studies were needed to confirm the link.

"Increasing evidence has linked changes in sleep to memory problems and dementia, but it's not clear whether these changes might be a cause or consequence.

"The people studied here were followed for a very short period, and one next step could be to investigate whether a lack of 'slow-wave' sleep may also be linked to a long-term decline in memory."

The myth of the eight-hour sleep

http://www.bbc.co.uk/news/magazine-16964783

Stephanie Hegarty

We often worry about lying awake in the middle of the night - but it could be good for you. A growing body of evidence from both science and history suggests that the eight-hour sleep may be unnatural.

In the early 1990s, psychiatrist Thomas Wehr conducted an experiment in which a group of people were plunged into darkness for 14 hours every day for a month.

It took some time for their sleep to regulate but by the fourth week the subjects had settled into a very distinct sleeping pattern. They slept first for four hours, then woke for one or two hours before falling into a second four-hour sleep.

Though sleep scientists were impressed by the study, among the general public the idea that we must sleep for eight consecutive hours persists.

In 2001, historian Roger Ekirch of Virginia Tech published a seminal paper, drawn from 16 years of research, revealing a wealth of historical evidence that humans used to sleep in two distinct chunks.

His book At Day's Close: Night in Times Past, published four years later, unearths more than 500 references to a segmented sleeping pattern - in diaries, court records, medical books and literature, from Homer's Odyssey to an anthropological account of modern tribes in Nigeria.

Much like the experience of Wehr's subjects, these references describe a first sleep which began about two hours after dusk, followed by waking period of one or two hours and then a second sleep.

"It's not just the number of references - it is the way they refer to it, as if it was common knowledge," Ekirch says.

During this waking period people were quite active. They often got up, went to the toilet or smoked tobacco and some even visited neighbours. Most people stayed in bed, read, wrote and often prayed. Countless prayer manuals from the late 15th Century offered special prayers for the hours in between sleeps.

And these hours weren't entirely solitary - people often chatted to bed-fellows or had sex.

A doctor's manual from 16th Century France even advised couples that the best time to conceive was not at the end of a long day's labour but "after the first sleep", when "they have more enjoyment" and "do it better".

Ekirch found that references to the first and second sleep started to disappear during the late 17th Century. This started among the urban upper classes in northern Europe and over the course of the next 200 years filtered down to the rest of Western society.

By the 1920s the idea of a first and second sleep had receded entirely from our social consciousness.

He attributes the initial shift to improvements in street lighting, domestic lighting and a surge in coffee houses - which were sometimes open all night. As the night became a place for legitimate activity and as that activity increased, the length of time people could dedicate to rest dwindled.

When segmented sleep was the norm

• "He knew this, even in the horror with which he started from his first sleep, and threw up the window to dispel it by the presence of some object, beyond the room, which had not been, as it were, the witness of his dream." Charles Dickens, Barnaby Rudge (1840)
• "Don Quixote followed nature, and being satisfied with his first sleep, did not solicit more. As for Sancho, he never wanted a second, for the first lasted him from night to morning." Miguel Cervantes, Don Quixote (1615)
• "And at the wakening of your first sleepe You shall have a hott drinke made, And at the wakening of your next sleepe Your sorrowes will have a slake." Early English ballad, Old Robin of Portingale
• The Tiv tribe in Nigeria employ the terms "first sleep" and "second sleep" to refer to specific periods of the night

In his new book, Evening's Empire, historianCraig Koslofsky puts forward an account of how this happened.

"Associations with night before the 17th Century were not good," he says. The night was a place populated by people of disrepute - criminals, prostitutes and drunks.

"Even the wealthy, who could afford candlelight, had better things to spend their money on. There was no prestige or social value associated with staying up all night."

That changed in the wake of the Reformation and the counter-Reformation. Protestants and Catholics became accustomed to holding secret services at night, during periods of persecution. If earlier the night had belonged to reprobates, now respectable people became accustomed to exploiting the hours of darkness.

This trend migrated to the social sphere too, but only for those who could afford to live by candlelight. With the advent of street lighting, however, socialising at night began to filter down through the classes.

In 1667, Paris became the first city in the world to light its streets, using wax candles in glass lamps. It was followed by Lille in the same year and Amsterdam two years later, where a much more efficient oil-powered lamp was developed.

London didn't join their ranks until 1684 but by the end of the century, more than 50 of Europe's major towns and cities were lit at night.

Night became fashionable and spending hours lying in bed was considered a waste of time.

"People were becoming increasingly time-conscious and sensitive to efficiency, certainly before the 19th Century," says Roger Ekirch. "But the industrial revolution intensified that attitude by leaps and bounds."

Strong evidence of this shifting attitude is contained in a medical journal from 1829 which urged parents to force their children out of a pattern of first and second sleep.

"If no disease or accident there intervene, they will need no further repose than that obtained in their first sleep, which custom will have caused to terminate by itself just at the usual hour.

"And then, if they turn upon their ear to take a second nap, they will be taught to look upon it as an intemperance not at all redounding to their credit."

Today, most people seem to have adapted quite well to the eight-hour sleep, but Ekirch believes many sleeping problems may have roots in the human body's natural preference for segmented sleep as well as the ubiquity of artificial light.

The condition first appears in literature at the end of the 19th Century, at the same time as accounts of segmented sleep disappear.This could be the root of a condition called sleep maintenance insomnia, where people wake during the night and have trouble getting back to sleep, he suggests.

"For most of evolution we slept a certain way," says sleep psychologist Gregg Jacobs. "Waking up during the night is part of normal human physiology."

The idea that we must sleep in a consolidated block could be damaging, he says, if it makes people who wake up at night anxious, as this anxiety can itself prohibit sleeps and is likely to seep into waking life too.

Russell Foster, a professor of circadian [body clock] neuroscience at Oxford, shares this point of view.

"Many people wake up at night and panic," he says. "I tell them that what they are experiencing is a throwback to the bi-modal sleep pattern."

A small city like Leipzig in central Germany employed 100 men to tend to 700 lamps

Stages of sleep

Every 60-100 minutes we go through a cycle of four stages of sleep

• Stage 1 is a drowsy, relaxed state between being awake and sleeping - breathing slows, muscles relax, heart rate drops
• Stage 2 is slightly deeper sleep - you may feel awake and this means that, on many nights, you may be asleep and not know it
• Stage 3 and Stage 4, or Deep Sleep - it is very hard to wake up from Deep Sleep because this is when there is the lowest amount of activity in your body
• After Deep Sleep, we go back to Stage 2 for a few minutes, and then enter Dream Sleep - also called REM (rapid eye movement) sleep - which, as its name suggests, is when you dream

In a full sleep cycle, a person goes through all the stages of sleep from one to four, then back down through stages three and two, before entering dream sleep

Source: Gregg Jacobs

But the majority of doctors still fail to acknowledge that a consolidated eight-hour sleep may be unnatural.

"Over 30% of the medical problems that doctors are faced with stem directly or indirectly from sleep. But sleep has been ignored in medical training and there are very few centres where sleep is studied," he says.

Jacobs suggests that the waking period between sleeps, when people were forced into periods of rest and relaxation, could have played an important part in the human capacity to regulate stress naturally.

In many historic accounts, Ekirch found that people used the time to meditate on their dreams.

"Today we spend less time doing those things," says Dr Jacobs. "It's not a coincidence that, in modern life, the number of people who report anxiety, stress, depression, alcoholism and drug abuse has gone up."

So the next time you wake up in the middle of the night, think of your pre-industrial ancestors and relax. Lying awake could be good for you.

Craig Koslofsky and Russell Foster appeared on The Forum from the BBC World Service. Listen to the programmehere.