Why Deep Breathing May Keep Us Calm

For generations, mothers have encouraged children to take long, slow breaths to fight anxiety. A long tradition of meditation likewise uses controlled breathing to induce tranquillity.

Now scientists at Stanford University may have uncovered for the first time why taking deep breaths can be so calming. The research, on a tiny group of neurons deep within the brains of mice, also underscores just how intricate and pervasive the links are within our body between breathing, thinking, behaving and feeling.

Breathing is one of the body’s most essential and elastic processes. Our breaths occur constantly and rhythmically, much like our hearts’ steady beating. But while we generally cannot change our hearts’ rhythm by choice, we can alter how we breathe, in some cases consciously, as in holding our breath, or with little volition, such as sighing, gasping or yawning.

But how the mind and body regulate breathing and vice versa at the cellular level has remained largely mysterious. More than 25 years ago, researchers at the University of California at Los Angeles first discovered a small bundle of about 3,000 interlinked neurons inside the brainstems of animals, including people, that seem to control most aspects of breathing. They dubbed these neurons the breathing pacemaker.

In the years since, though, little progress had been made in understanding precisely how those cells work.

But recently, a group of scientists at Stanford and other universities, including some of the U.C.L.A. researchers, began using sophisticated new genetics techniques to study individual neurons in the pacemaker. By microscopically tracking different proteins produced by the genes in each cell, the scientists could group the neurons into “types.”

They eventually identified about 65 different types of neurons in the pacemaker, each presumably with a unique responsibility for regulating some aspect of breathing.

The scientists confirmed that idea in a remarkable study published last year in Nature, in which they bred mice with a single type of pacemaker cell that could be disabled. When they injected the animals with a virus that killed only those cells, the mice stopped sighing, the researchers discovered. Mice, like people, normally sigh every few minutes, even if we and they are unaware of doing so. Without instructions from these cells, the sighing stopped.

But that study, while literally breathtaking, raised new questions about the capabilities of other neurons in the pacemaker.

So for the newest study, which was published recently in Science, the researchers carefully disabled yet another type of breathing-related neuron in mice. Afterward, the animals at first seemed unchanged. They sighed, yawned and otherwise breathed just as before.

But when the mice were placed in unfamiliar cages, which normally would incite jittery exploring and lots of nervous sniffing — a form of rapid breathing — the animals instead sat serenely grooming themselves.

“They were, for mice, remarkably chill,” says Dr. Mark Krasnow, a professor of biochemistry at Stanford who oversaw the research.

To better understand why, the researchers next looked at brain tissue from the mice to determine whether and how the disabled neurons might connect to other parts of the brain.

It turned out that the particular neurons in question showed direct biological links to a portion of the brain that is known to be involved in arousal. This area sends signals to multiple other parts of the brain that, together, direct us to wake up, be alert and, sometimes, become anxious or frantic.

In the mellow mice, this area of the brain remained quiet.

“What we think was going on” was that the disabled neurons normally would detect activity in other neurons within the pacemaker that regulate rapid breathing and sniffing, says Dr. Kevin Yackle, now a faculty fellow at the University of California, San Francisco, who, as a graduate researcher at Stanford, led the study.

The disabled neurons would then alert the brain that something potentially worrisome was going on with the mouse since it was sniffing, and the brain should start ramping up the machinery of worry and panic. So a few tentative sniffs could result in a state of anxiety that, in a rapid feedback loop, would make the animal sniff more and become increasingly anxious.

Or, without that mechanism, it would remain tranquil, a mouse of Zen.

The implication of this work, both Dr. Krasnow and Dr. Yackle say, is that taking deep breaths is calming because it does not activate the neurons that communicate with the brain’s arousal center.

Whether deep breathing has its own, separate set of regulatory neurons and whether those neurons talk to parts of the brain involved in soothing and pacifying the body is still unknown, although the scientists plan to continue studying the activity of each of the subtypes of neurons within the pacemaker. This area of research is in its infancy, Dr. Yackle says.

It also so far involves mice rather than people, although we are known to have breathing pacemakers that closely resemble those in rodents.

But even if preliminary, this research bolsters an ancient axiom, Dr. Krasnow says. “Mothers were probably right all along,” he says, “when they told us to stop and take a deep breath when we got upset.”

Thoughts on Vegas, and Why Men Keep Doing This

While we acknowledge that this post may stray a bit from our usual content, in the wake of the Las Vegas tragedy we believe this provocative content is worth reading by our followers. Excerpts from the article by Charlie Hoehn on beyourself.

“There’s probably no way to ever know why a human being could do something like this to other human beings.”

Sadly, researchers know a lot about why human beings — particularly men — do things like this.

Why mass shootings keep happening

It’s tempting to say the mass shooter’s motive was simply “pure evil,” or to blame the media or guns, but that absolves us of looking deeply at what each of us — as individuals, family members, friends, and community members — might be missing.

1- Men in the United States are chronically lonely.

Boys in the United States — just like all human beings — need touch, caring, warmth, empathy, and close relationships. But as we grow up, most of us lose those essential components of our humanity. What’s worse: we have no idea how to ask for those things, or admit we need them, because we’re afraid it will make us look weak. As a man, you might be thinking, “Not me, I’ve got drinking buddies. I play poker with the guys. I’ve got friends.”

From an early age, we have an unhealthy ideal of masculinity that we try to live up to. Part of that ideal tells us that Real men do everything on their ownReal men don’t cry. Real men express anger through violence. The byproduct is isolation. Most men spend the majority of their adult lives without deeper friendships, or any real sense of community. Not to mention a complete inability to release anger or sadness in a healthy way.

There is a fantastic documentary called The Mask You Live In, which explains how boys in our society are ultimately shaped into mentally unstable adults. My friend Ryan recommended this film to me, after confiding that he cried throughout the entire thing. I cried, as well.


“We’re seeing a rise of loneliness and isolation. No one kills themselves when they’re hungry; we kill ourselves when we’re lonely. And we act out, as well.

  • In the 1960’s, there was one school shooting.
  • In the 1980’s, there were 27.
  • In the 1990’s, there were 58.
  • In the past decade, there have been over 120.

How do we combat the loneliness that kids are feeling? All of them attacked people in their own community, and all of them attack people they blamed for their own loneliness.”


This loneliness compounds as men grow older. Without deeper friendships or a strong sense of community, the isolation is soul-deadening and maddening. You are alone. Any slight from someone you care about can feel emotionally traumatizing. After enough rejections and feeling like an outcast, you begin to believe that people are just cruel and not worth the effort. You perceive people as threats.


2- Men in the United States are deprived of play opportunities.

Homo sapiens play more than any other species. It’s impossible to prevent a human from playing. We play shortly after we are born, and the healthiest (and least stressed) humans tend to play for their entire lives.

Play may be God’s greatest gift to mankind. It’s how we form friendships, and learn skills, and master difficult things that help us survive. Play is a release valve for stress, and an outlet for creativity. Play brings us music, comedy, dance, and everything we value.

Above all, play is how we bond with each other — it’s how we communicate “I am safe to be around, I am not a threat.” Play is how we form connections with other humans. The irony is that loneliness would not be a problem if we all got ample time to play. Not only would we have deeper friendships, we’d also have better relationships with ourselves. Play allows us to enjoy our own company.

There is a strong correlation with play deprivation and mental illness.

When you deprive mammals of play, it leads to chronic depression. When you deprive a human child of play, their mental and emotional health deteriorate. Play suppression has enormous health consequences.

This is in alignment with Dr. Peter Gray’s research, who studied the epidemic of mental illness and the decline in play:

“Over the past half century, in the United States and other developed nations, children’s free play with other children has declined sharply. Over the same period, anxiety, depression, suicide, feelings of helplessness, and narcissism have increased sharply in children, adolescents, and young adults… The decline in play has contributed to the rise in the psychopathology of young people.


This is why I believe mental illness may be the biggest health crisis of our lifetimes. Because those kids will grow up into isolated adults who don’t know how to play, or seek out their friends when they are lonely. They have no emotional support.

They are alone.


Universal among violent criminals was the fact that they were keeping a secret. A central secret. And that secret was that they felt ashamed— deeply ashamed, chronically ashamed, acutely ashamed.

ALL OF US will face difficult times in our lives where we will experience shame, humiliation, disrespect, and ridicule. Do you know what gets us through those hard times?

Friendship: The love and support you get, from the people you play with.

“I never had any friends later on like the ones I had when I was twelve. Jesus, does anyone?” — Stand by Me, final line

Whatever the case, these factors about mass shooters are often true:

  1. They are deeply lonely. They have no significant friendships to rely on, and very few quality people to confide in.
  2. They experienced ongoing play deprivation. Their innate ability was crippled, and they struggle to maintain a healthy emotional connection with themselves and others.
  3. They are deeply ashamed. They experienced extreme ridicule, rejection, or humiliation.

Are there other factors at play here?  Read the entire article here >>

Be Yourself

10 Side Effects of Prolonged Sitting

By Lori Diamos for Athletico Physical Therapy

Serious Side Effects of Prolonged Sitting

Our children do it at school, many of us do it at work, most of us do it while commuting, and too many of us also do it recreationally. What is that magic “it?”  If you guessed sitting then you hit the nail on the head.


2008 study by Vanderbilt University revealed that on average, most people sit 7.7 hours per day. Unfortunately, all of this time sitting comes at a price. Below are 10 side effects prolonged sitting has on your health and well-being.

  1. Altered posture and alignment: Gravity and fatigue tend to take over when you sit for too long, leading to a forward head, rounded shoulder and even slumped back posture. The stress and strain that come with altered positioning can lead to a myriad of different issues, like neck/low back pain, shoulder spurs or impingement syndrome, trigger points, and even disc degeneration.
  1. Tight muscles: The altered posture mentioned above leads to the neck, hip and shoulder flexors contracting. Over time, this can cause stress, strain and muscle tension.
  1. Weakness:  When areas are overstretched or go dormant for long periods of time, weakness ensues. Sitting can cause a lack of strength in the back (erector spinae), scapular stabilizers (middle trapezius, rhomboids, latissimus dorsi and lower trapezius), buttocks (gluteus medius, minimus and maximus), and core (rectus abdominis, obliques and transversus abdominis).
  1. Decreased cardiovascular health: When you are sedentary, the heart – just like any other muscle – is not being challenged or pumping blood as vigorously. This can affect endurance, metabolism, blood pressure, cholesterol levels and other cardiovascular health factors.
  1. Obesity risk increases: Inactivity from sitting lowers the metabolism and the body’s ability to metabolize fat. I-Min Lee, a professor of medicine at Harvard Medical School, notes that we burn 30 percent more calories standing than sitting. Cumulatively this can make a difference in your health in terms of weight control.
  1. Diabetes (type 2) risk increases: Researchers from the University of Missouri found that when one goes from high activity (10000 steps/day) to low activity (fewer than 5000 steps/day), insulin levels can be raised and enzyme activity decreased. This can contribute to a greater likelihood of developing type 2 diabetes.
  1. Psychological stressors: According to an article from Psychology Today, sitting can increase depression, anxiety and lower mental well-being.
  1. Altered digestion: Prolonged sitting after eating can compress the abdominal cavity thus slowing down digestion, which can lead to various issues like heartburn and constipation.
  1. Cancer risk increases: Though the direct cause is not fully understood, an article series from the British Medical Journal (BMJ) showed sitting increases the risk of lung cancer by 54 percent, uterine cancer by 66 percent and colon cancer by 30 percent.
  1. Overall mortality: prolonged sitting increases the risk of all-cause mortality by 49 percent per research findings in a 2012 Diabetologia.

The long and short of it is that there can be consequences when we don’t live a healthy lifestyle that includes activity. Research even shows that people who vigorously exercise either before or after excessive sitting cannot undo many of the negative health factors.7 So where does that leave us? Some experts say you should start standing up at work for at least two hours a day, and work your way toward four. If excessive sitting is leaving you sore, you can also schedule an appointment for a free injury screen at your nearest Athletico location.

Share some of your favorite ways to minimize sitting in the comments below and stay tuned for our follow up article addressing just that.

Schedule a Complimentary Injury Screen

The shorter your sleep, the shorter your life

Image result for peaceful sleep

Matthew Walker has learned to dread the question “What do you do?” At parties, it signals the end of his evening; thereafter, his new acquaintance will inevitably cling to him like ivy. On an aeroplane, it usually means that while everyone else watches movies or reads a thriller, he will find himself running an hours-long salon for the benefit of passengers and crew alike. “I’ve begun to lie,” he says. “Seriously. I just tell people I’m a dolphin trainer. It’s better for everyone.”

Leading neuroscientist Matthew Walker on why sleep deprivation is increasing our risk of cancer, heart attack and Alzheimer’s – and what you can do about it.

Walker is a sleep scientist. To be specific, he is the director of the Center for Human Sleep Science at the University of California, Berkeley, a research institute whose goal – possibly unachievable – is to understand everything about sleep’s impact on us, from birth to death, in sickness and health. No wonder, then, that people long for his counsel. As the line between work and leisure grows ever more blurred, rare is the person who doesn’t worry about their sleep. But even as we contemplate the shadows beneath our eyes, most of us don’t know the half of it – and perhaps this is the real reason he has stopped telling strangers how he makes his living. When Walker talks about sleep he can’t, in all conscience, limit himself to whispering comforting nothings about camomile tea and warm baths. It’s his conviction that we are in the midst of a “catastrophic sleep-loss epidemic”, the consequences of which are far graver than any of us could imagine. This situation, he believes, is only likely to change if government gets involved.

Walker has spent the last four and a half years writing Why We Sleep, a complex but urgent book that examines the effects of this epidemic close up, the idea being that once people know of the powerful links between sleep loss and, among other things, Alzheimer’s disease, cancer, diabetes, obesity and poor mental health, they will try harder to get the recommended eight hours a night (sleep deprivation, amazing as this may sound to Donald Trump types, constitutes anything less than seven hours). But, in the end, the individual can achieve only so much. Walker wants major institutions and law-makers to take up his ideas, too. “No aspect of our biology is left unscathed by sleep deprivation,” he says. “It sinks down into every possible nook and cranny. And yet no one is doing anything about it. Things have to change: in the workplace and our communities, our homes and families. But when did you ever see an NHS poster urging sleep on people? When did a doctor prescribe, not sleeping pills, but sleep itself? It needs to be prioritised, even incentivised. Sleep loss costs the UK economy over £30bn a year in lost revenue, or 2% of GDP. I could double the NHS budget if only they would institute policies to mandate or powerfully encourage sleep.”

Why, exactly, are we so sleep-deprived? What has happened over the course of the last 75 years? In 1942, less than 8% of the population was trying to survive on six hours or less sleep a night; in 2017, almost one in two people is. The reasons are seemingly obvious. “First, we electrified the night,” Walker says. “Light is a profound degrader of our sleep. Second, there is the issue of work: not only the porous borders between when you start and finish, but longer commuter times, too. No one wants to give up time with their family or entertainment, so they give up sleep instead. And anxiety plays a part. We’re a lonelier, more depressed society. Alcohol and caffeine are more widely available. All these are the enemies of sleep.”

But Walker believes, too, that in the developed world sleep is strongly associated with weakness, even shame. “We have stigmatised sleep with the label of laziness. We want to seem busy, and one way we express that is by proclaiming how little sleep we’re getting. It’s a badge of honour. When I give lectures, people will wait behind until there is no one around and then tell me quietly: ‘I seem to be one of those people who need eight or nine hours’ sleep.’ It’s embarrassing to say it in public. They would rather wait 45 minutes for the confessional. They’re convinced that they’re abnormal, and why wouldn’t they be? We chastise people for sleeping what are, after all, only sufficient amounts. We think of them as slothful. No one would look at an infant baby asleep, and say ‘What a lazy baby!’ We know sleeping is non-negotiable for a baby. But that notion is quickly abandoned [as we grow up]. Humans are the only species that deliberately deprive themselves of sleep for no apparent reason.” In case you’re wondering, the number of people who can survive on five hours of sleep or less without any impairment, expressed as a percent of the population and rounded to a whole number, is zero.

The world of sleep science is still relatively small. But it is growing exponentially, thanks both to demand (the multifarious and growing pressures caused by the epidemic) and to new technology (such as electrical and magnetic brain stimulators), which enables researchers to have what Walker describes as “VIP access” to the sleeping brain. Walker, who is 44 and was born in Liverpool, has been in the field for more than 20 years, having published his first research paper at the age of just 21. “I would love to tell you that I was fascinated by conscious states from childhood,” he says. “But in truth, it was accidental.” He started out studying for a medical degree in Nottingham. But having discovered that doctoring wasn’t for him – he was more enthralled by questions than by answers – he switched to neuroscience, and after graduation, began a PhD in neurophysiology supported by the Medical Research Council. It was while working on this that he stumbled into the realm of sleep.

“I was looking at the brainwave patterns of people with different forms of dementia, but I was failing miserably at finding any difference between them,” he recalls now. One night, however, he read a scientific paper that changed everything. It described which parts of the brain were being attacked by these different types of dementia: “Some were attacking parts of the brain that had to do with controlled sleep, while other types left those sleep centres unaffected. I realised my mistake. I had been measuring the brainwave activity of my patients while they were awake, when I should have been doing so while they were asleep.” Over the next six months, Walker taught himself how to set up a sleep laboratory and, sure enough, the recordings he made in it subsequently spoke loudly of a clear difference between patients. Sleep, it seemed, could be a new early diagnostic litmus test for different subtypes of dementia.

After this, sleep became his obsession. “Only then did I ask: what is this thing called sleep, and what does it do? I was always curious, annoyingly so, but when I started to read about sleep, I would look up and hours would have gone by. No one could answer the simple question: why do we sleep? That seemed to me to be the greatest scientific mystery. I was going to attack it, and I was going to do that in two years. But I was naive. I didn’t realise that some of the greatest scientific minds had been trying to do the same thing for their entire careers. That was two decades ago, and I’m still cracking away.” After gaining his doctorate, he moved to the US. Formerly a professor of psychiatry at Harvard Medical School, he is now professor of neuroscience and psychology at the University of California.

Does his obsession extend to the bedroom? Does he take his own advice when it comes to sleep? “Yes. I give myself a non-negotiable eight-hour sleep opportunity every night, and I keep very regular hours: if there is one thing I tell people, it’s to go to bed and to wake up at the same time every day, no matter what. I take my sleep incredibly seriously because I have seen the evidence. Once you know that after just one night of only four or five hours’ sleep, your natural killer cells – the ones that attack the cancer cells that appear in your body every day – drop by 70%, or that a lack of sleep is linked to cancer of the bowel, prostate and breast, or even just that the World Health Organisation has classed any form of night-time shift work as a probable carcinogen, how could you do anything else?”

There is, however, a sting in the tale. Should his eyelids fail to close, Walker admits that he can be a touch “Woody Allen-neurotic”. When, for instance, he came to London over the summer, he found himself jet-lagged and wide awake in his hotel room at two o’clock in the morning. His problem then, as always in these situations, was that he knew too much. His brain began to race. “I thought: my orexin isn’t being turned off, the sensory gate of my thalamus is wedged open, my dorsolateral prefrontal cortex won’t shut down, and my melatonin surge won’t happen for another seven hours.” What did he do? In the end, it seems, even world experts in sleep act just like the rest of us when struck by the curse of insomnia. He turned on a light and read for a while.

Will Why We Sleep have the impact its author hopes? I’m not sure: the science bits, it must be said, require some concentration. But what I can tell you is that it had a powerful effect on me. After reading it, I was absolutely determined to go to bed earlier – a regime to which I am sticking determinedly. In a way, I was prepared for this. I first encountered Walker some months ago, when he spoke at an event at Somerset House in London, and he struck me then as both passionate and convincing (our later interview takes place via Skype from the basement of his “sleep centre”, a spot which, with its bedrooms off a long corridor, apparently resembles the ward of a private hospital). But in another way, it was unexpected. I am mostly immune to health advice. Inside my head, there is always a voice that says “just enjoy life while it lasts”.

The evidence Walker presents, however, is enough to send anyone early to bed. It’s no kind of choice at all. Without sleep, there is low energy and disease. With sleep, there is vitality and health. More than 20 large scale epidemiological studies all report the same clear relationship: the shorter your sleep, the shorter your life. To take just one example, adults aged 45 years or older who sleep less than six hours a night are 200% more likely to have a heart attack or stroke in their lifetime, as compared with those sleeping seven or eight hours a night (part of the reason for this has to do with blood pressure: even just one night of modest sleep reduction will speed the rate of a person’s heart, hour upon hour, and significantly increase their blood pressure).

A lack of sleep also appears to hijack the body’s effective control of blood sugar, the cells of the sleep-deprived appearing, in experiments, to become less responsive to insulin, and thus to cause a prediabetic state of hyperglycaemia. When your sleep becomes short, moreover, you are susceptible to weight gain. Among the reasons for this are the fact that inadequate sleep decreases levels of the satiety-signalling hormone, leptin, and increases levels of the hunger-signalling hormone, ghrelin. “I’m not going to say that the obesity crisis is caused by the sleep-loss epidemic alone,” says Walker. “It’s not. However, processed food and sedentary lifestyles do not adequately explain its rise. Something is missing. It’s now clear that sleep is that third ingredient.” Tiredness, of course, also affects motivation.

Sleep has a powerful effect on the immune system, which is why, when we have flu, our first instinct is to go to bed: our body is trying to sleep itself well. Reduce sleep even for a single night, and your resilience is drastically reduced. If you are tired, you are more likely to catch a cold. The well-rested also respond better to the flu vaccine. As Walker has already said, more gravely, studies show that short sleep can affect our cancer-fighting immune cells. A number of epidemiological studies have reported that night-time shift work and the disruption to circadian sleep and rhythms that it causes increase the odds of developing cancers including breast, prostate, endometrium and colon.

Getting too little sleep across the adult lifespan will significantly raise your risk of developing Alzheimer’s disease. The reasons for this are difficult to summarise, but in essence it has to do with the amyloid deposits (a toxin protein) that accumulate in the brains of those suffering from the disease, killing the surrounding cells. During deep sleep, such deposits are effectively cleaned from the brain. What occurs in an Alzheimer’s patient is a kind of vicious circle. Without sufficient sleep, these plaques build up, especially in the brain’s deep-sleep-generating regions, attacking and degrading them. The loss of deep sleep caused by this assault therefore lessens our ability to remove them from the brain at night. More amyloid, less deep sleep; less deep sleep, more amyloid, and so on. (In his book, Walker notes “unscientifically” that he has always found it curious that Margaret Thatcher and Ronald Reagan, both of whom were vocal about how little sleep they needed, both went on to develop the disease; it is, moreover, a myth that older adults need less sleep.) Away from dementia, sleep aids our ability to make new memories, and restores our capacity for learning.

And then there is sleep’s effect on mental health. When your mother told you that everything would look better in the morning, she was wise. Walker’s book includes a long section on dreams (which, says Walker, contrary to Dr Freud, cannot be analysed). Here he details the various ways in which the dream state connects to creativity. He also suggests that dreaming is a soothing balm. If we sleep to remember (see above), then we also sleep to forget. Deep sleep – the part when we begin to dream – is a therapeutic state during which we cast off the emotional charge of our experiences, making them easier to bear. Sleep, or a lack of it, also affects our mood more generally. Brain scans carried out by Walker revealed a 60% amplification in the reactivity of the amygdala – a key spot for triggering anger and rage – in those who were sleep-deprived. In children, sleeplessness has been linked to aggression and bullying; in adolescents, to suicidal thoughts. Insufficient sleep is also associated with relapse in addiction disorders. A prevailing view in psychiatry is that mental disorders cause sleep disruption. But Walker believes it is, in fact, a two-way street. Regulated sleep can improve the health of, for instance, those with bipolar disorder.

I’ve mentioned deep sleep in this (too brief) summary several times. What is it, exactly? We sleep in 90-minute cycles, and it’s only towards the end of each one of these that we go into deep sleep. Each cycle comprises two kinds of sleep. First, there is NREM sleep (non-rapid eye movement sleep); this is then followed by REM (rapid eye movement) sleep. When Walker talks about these cycles, which still have their mysteries, his voice changes. He sounds bewitched, almost dazed.

“During NREM sleep, your brain goes into this incredible synchronised pattern of rhythmic chanting,” he says. “There’s a remarkable unity across the surface of the brain, like a deep, slow mantra. Researchers were once fooled that this state was similar to a coma. But nothing could be further from the truth. Vast amounts of memory processing is going on. To produce these brainwaves, hundreds of thousands of cells all sing together, and then go silent, and on and on. Meanwhile, your body settles into this lovely low state of energy, the best blood-pressure medicine you could ever hope for. REM sleep, on the other hand, is sometimes known as paradoxical sleep, because the brain patterns are identical to when you’re awake. It’s an incredibly active brain state. Your heart and nervous system go through spurts of activity: we’re still not exactly sure why.”

Does the 90-minute cycle mean that so-called power naps are worthless? “They can take the edge off basic sleepiness. But you need 90 minutes to get to deep sleep, and one cycle isn’t enough to do all the work. You need four or five cycles to get all the benefit.” Is it possible to have too much sleep? This is unclear. “There is no good evidence at the moment. But I do think 14 hours is too much. Too much water can kill you, and too much food, and I think ultimately the same will prove to be true for sleep.” How is it possible to tell if a person is sleep-deprived? Walker thinks we should trust our instincts. Those who would sleep on if their alarm clock was turned off are simply not getting enough. Ditto those who need caffeine in the afternoon to stay awake. “I see it all the time,” he says. “I get on a flight at 10am when people should be at peak alert, and I look around, and half of the plane has immediately fallen asleep.”

So what can the individual do? First, they should avoid pulling “all-nighters”, at their desks or on the dancefloor. After being awake for 19 hours, you’re as cognitively impaired as someone who is drunk. Second, they should start thinking about sleep as a kind of work, like going to the gym (with the key difference that it is both free and, if you’re me, enjoyable). “People use alarms to wake up,” Walker says. “So why don’t we have a bedtime alarm to tell us we’ve got half an hour, that we should start cycling down?” We should start thinking of midnight more in terms of its original meaning: as the middle of the night. Schools should consider later starts for students; such delays correlate with improved IQs. Companies should think about rewarding sleep. Productivity will rise, and motivation, creativity and even levels of honesty will be improved. Sleep can be measured using tracking devices, and some far-sighted companies in the US already give employees time off if they clock enough of it. Sleeping pills, by the way, are to be avoided. Among other things, they can have a deleterious effect on memory.

Those who are focused on so-called “clean” sleep are determined to outlaw mobiles and computers from the bedroom – and quite right, too, given the effect of LED-emitting devices on melatonin, the sleep-inducing hormone. Ultimately, though, Walker believes that technology will be sleep’s saviour. “There is going to be a revolution in the quantified self in industrial nations,” he says. “We will know everything about our bodies from one day to the next in high fidelity. That will be a seismic shift, and we will then start to develop methods by which we can amplify different components of human sleep, and do that from the bedside. Sleep will come to be seen as a preventive medicine.”

What questions does Walker still most want to answer? For a while, he is quiet. “It’s so difficult,” he says, with a sigh. “There are so many. I would still like to know where we go, psychologically and physiologically, when we dream. Dreaming is the second state of human consciousness, and we have only scratched the surface so far. But I would also like to find out when sleep emerged. I like to posit a ridiculous theory, which is: perhaps sleep did not evolve. Perhaps it was the thing from which wakefulness emerged.” He laughs. “If I could have some kind of medical Tardis and go back in time to look at that, well, I would sleep better at night.”

Sleep in numbers

■ Two-thirds of adults in developed nations fail to obtain the nightly eight hours of sleep recommended by the World Health Organisation.

■ An adult sleeping only 6.75 hours a night would be predicted to live only to their early 60s without medical intervention.

■ A 2013 study reported that men who slept too little had a sperm count 29% lower than those who regularly get a full and restful night’s sleep.

■ If you drive a car when you have had less than five hours’ sleep, you are 4.3 times more likely to be involved in a crash. If you drive having had four hours, you are 11.5 times more likely to be involved in an accident.

■ A hot bath aids sleep not because it makes you warm, but because your dilated blood vessels radiate inner heat, and your core body temperature drops. To successfully initiate sleep, your core temperature needs to drop about 1C.

■ The time taken to reach physical exhaustion by athletes who obtain anything less than eight hours of sleep, and especially less than six hours, drops by 10-30%.

■ There are now more than 100 diagnosed sleep disorders, of which insomnia is the most common.

■ Morning types, who prefer to awake at or around dawn, make up about 40% of the population. Evening types, who prefer to go to bed late and wake up late, account for about 30%. The remaining 30% lie somewhere in between.