OFFICE WORKERS, STAND UP FROM YOUR DESK FOR TWO HOURS A DAY

We’ve known for some time that too much sitting increases your risk of diabetes, certain cancers, heart disease and early death. But until now it’s been unclear how much standing during the work day may counter this increased risk.

Guidelines published today in the British Journal of Sports Medicine urge employers change their workplace culture and social norms around the sedentary office. It recommends desk-based office workers spend at least two hours of their working day standing or moving, and to gradually progress to four hours.

Commissioned by Public Health England and Active Working Community Interest Company, an international group of experts from the United Kingdom, United States and Australia (including myself) spent several months reviewing the existing evidence. There was much lively “debate” and several revisions before reaching the final recommendations.

As well as two hours of standing and light activity such as light walking each day (progressing to four hours), the guidelines recommend:

Height-adjustable desks allow users to alternate between sitting and standing. | Photo Credit: Dennis Yang/Flickr, CC BY

• Regularly breaking up seated-based work with standing-based work, with the use of adjustable sit-stand desks or work stations
• Avoiding prolonged static standing, which may be as harmful as prolonged sitting
• Altering posture or light walking to alleviate possible musculoskeletal pain and fatigue while you adapt to more standing or moving
• Warning staff about the potential dangers of too much time sitting down either at work or at home.

The recommendations are based largely on observational and retrospective studies or short-term intervention studies showing breaks from sitting reduce the risk of developing heart disease and metabolic disorders such as diabetes. Clearly, longer-term intervention studies are needed and future refinements to the guidelines will be required as more evidence is published.

There are two elements of the recommendations that could be easily overlooked but are of great importance. First, the two and eventually four hours a day of standing and light activity should be accumulated across the working day to avoid introducing other harms associated with prolonged static standing. These include blood pooling in the lower legs and feet and varicose veins.

Regularly breaking up prolonged seated work with standing-based work is the key message here. This is consistent with the 2014 Australian Physical Activity and Sedentary Behaviour guidelines that recommend adults to “minimise the time spent in prolonged sitting” and “break up long periods of sitting as often as possible”.

Second, the initial guidelines provide the platform for employers to further raise awareness among employees that prolonged sitting, aggregated from work and leisure time, may significantly increase disease risk. Adults who sit for ten hours per day have an estimated 34% higher risk of early death, even if they exercise regularly.

The use of a sit-to-stand adjustable work desk is one solution to the problem of prolonged sitting in the workplace. But these desks shouldn’t be viewed as the only solution. It’s also important to note that long-term studies of the likely impact on health outcomes are not yet available.

Employers should provide alternative ways of working to those that have become so ingrained in modern workplaces.

A glaring example is long meetings where participants must sit, uninterrupted. Organisations such as the National Heart Foundation of Australia are now instituting “standing agenda items” so participants can stand up and move around the room. In the past this may have been seen as being disruptive.

Other organisations are providing headsets that allow workers to move about during long phone calls.

Many offices are removing personal waste bins and opting for a central bin to encourage movement.

If you need a prompt to get up and moving at work, give up the chair for a day on June 11 for the campaign On Your Feet Australia. It might also give employers the nudge they need to start changing sedentary workplace cultures to improve their employees’ health and reduce the nation’s burden of heart disease and diabetes.

David Dunstan, Associate Professor and Laboratory Head of Physical Activity, Baker IDI Heart & Diabetes Institute

HERE’S WHAT HAPPENS TO YOUR BRAIN WHEN YOU GIVE UP SUGAR

By Jordan Gaines Lewis, Neuroscience Doctoral Candidate Penn State College of Medicine

Anyone who knows me also knows that I have a huge sweet tooth. I always have. My friend and fellow graduate student Andrew is equally afflicted, and living in Hershey, Pennsylvania – the “Chocolate Capital of the World” – doesn’t help either of us.

But Andrew is braver than I am. Last year, he gave up sweets for Lent. I can’t say that I’m following in his footsteps this year, but if you are abstaining from sweets for Lent this year, here’s what you can expect over the next 40 days.

SUGAR: NATURAL REWARD, UNNATURAL FIX

In neuroscience, food is something we call a “natural reward.” In order for us to survive as a species, things like eating, having sex and nurturing others must be pleasurable to the brain so that these behaviours are reinforced and repeated.

Evolution has resulted in the mesolimbic pathway, a brain system that deciphers these natural rewards for us. When we do something pleasurable, a bundle of neurons called the ventral tegmental area uses the neurotransmitter dopamine to signal to a part of the brain called the nucleus accumbens. The connection between the nucleus accumbens and our prefrontal cortex dictates our motor movement, such as deciding whether or not to taking another bite of that delicious chocolate cake. The prefrontal cortex also activates hormones that tell our body: “Hey, this cake is really good. And I’m going to remember that for the future.”

evolutionarily, our mesolimbic pathway reinforces that sweet things provide a healthy source of carbohydrates for our bodies.

Not all foods are equally rewarding, of course. Most of us prefer sweets over sour and bitter foods because, evolutionarily, our mesolimbic pathway reinforces that sweet things provide a healthy source of carbohydrates for our bodies. When our ancestors went scavenging for berries, for example, sour meant “not yet ripe,” while bitter meant “alert – poison!”

Fruit is one thing, but modern diets have taken on a life of their own. A decade ago, it was estimated that the average American consumed 22 teaspoons of added sugar per day, amounting to an extra 350 calories; it may well have risen since then. A few months ago, one expert suggested that the average Briton consumes 238 teaspoons of sugar each week.

Today, with convenience more important than ever in our food selections, it’s almost impossible to come across processed and prepared foods that don’t have added sugars for flavour, preservation, or both.

These added sugars are sneaky – and unbeknown to many of us, we’ve become hooked. In ways that drugs of abuse – such as nicotine, cocaine and heroin – hijack the brain’s reward pathway and make users dependent, increasing neuro-chemical and behavioural evidence suggests that sugar is addictive in the same way, too.

SUGAR ADDICTION IS REAL

“The first few days are a little rough,” Andrew told me about his sugar-free adventure last year. “It almost feels like you’re detoxing from drugs. I found myself eating a lot of carbs to compensate for the lack of sugar.”

There are four major components of addiction: bingeing, withdrawal, craving, and cross-sensitisation (the notion that one addictive substance predisposes someone to becoming addicted to another). All of these components have been observedin animal models of addiction – for sugar, as well as drugs of abuse.

A typical experiment goes like this: rats are deprived of food for 12 hours each day, then given 12 hours of access to a sugary solution and regular chow. After a month of following this daily pattern, rats display behaviours similar to those on drugs of abuse. They’ll binge on the sugar solution in a short period of time, much more than their regular food. They also show signs of anxiety and depression during the food deprivation period. Many sugar-treated rats who are later exposed to drugs, such as cocaine and opiates, demonstrate dependent behaviours towards the drugs compared to rats who did not consume sugar beforehand.

Over the long term, regular sugar consumption actually changes the gene expression and availability of dopamine receptors in both the midbrain and frontal cortex…

Like drugs, sugar spikes dopamine release in the nucleus accumbens. Over the long term, regular sugar consumption actually changes the gene expression and availability of dopamine receptors in both the midbrain and frontal cortex. Specifically, sugar increases the concentration of a type of excitatory receptor called D1, but decreases another receptor type called D2, which is inhibitory. Regular sugar consumption also inhibits the action of the dopamine transporter, a protein which pumps dopamine out of the synapse and back into the neuron after firing.

In short, this means that repeated access to sugar over time leads to prolonged dopamine signalling, greater excitation of the brain’s reward pathways and a need for even more sugar to activate all of the midbrain dopamine receptors like before. The brain becomes tolerant to sugar – and more is needed to attain the same “sugar high.”

SUGAR WITHDRAWAL IS ALSO REAL

Although these studies were conducted in rodents, it’s not far-fetched to say that the same primitive processes are occurring in the human brain, too. “The cravings never stopped, [but that was] probably psychological,” Andrew told me. “But it got easier after the first week or so.”

In a 2002 study by Carlo Colantuoni and colleagues of Princeton University, rats who had undergone a typical sugar dependence protocol then underwent “sugar withdrawal.” This was facilitated by either food deprivation or treatment with naloxone, a drug used for treating opiate addiction which binds to receptors in the brain’s reward system. Both withdrawal methods led to physical problems, including teeth chattering, paw tremors, and head shaking. Naloxone treatment also appeared to make the rats more anxious, as they spent less time on an elevated apparatus that lacked walls on either side.

Similar withdrawal experiments by others also report behaviour similar to depression in tasks such as the forced swim test. Rats in sugar withdrawal are more likely to show passive behaviours (like floating) than active behaviours (like trying to escape) when placed in water, suggesting feelings of helplessness.

A new study published by Victor Mangabeira and colleagues in this month’s Physiology & Behavior reports that sugar withdrawal is also linked to impulsive behaviour. Initially, rats were trained to receive water by pushing a lever. After training, the animals returned to their home cages and had access to a sugar solution and water, or just water alone. After 30 days, when rats were again given the opportunity to press a lever for water, those who had become dependent on sugar pressed the lever significantly more times than control animals, suggesting impulsive behaviour.

These are extreme experiments, of course. We humans aren’t depriving ourselves of food for 12 hours and then allowing ourselves to binge on soda and doughnuts at the end of the day. But these rodent studies certainly give us insight into the neuro-chemical underpinnings of sugar dependence, withdrawal, and behaviour.

Through decades of diet programmes and best-selling books, we’ve toyed with the notion of “sugar addiction” for a long time. There are accounts of those in “sugar withdrawal” describing food cravings, which can trigger relapse and impulsive eating. There are also countless articles and books about the boundless energy and new-found happiness in those who have sworn off sugar for good. But despite the ubiquity of sugar in our diets, the notion of sugar addiction is still a rather taboo topic.

Are you still motivated to give up sugar for Lent? You might wonder how long it will take until you’re free of cravings and side-effects, but there’s no answer – everyone is different and no human studies have been done on this. But after 40 days, it’s clear that Andrew had overcome the worst, likely even reversing some of his altered dopamine signalling. “I remember eating my first sweet and thinking it was too sweet,” he said. “I had to rebuild my tolerance.”

And as regulars of a local bakery in Hershey – I can assure you, readers, that he has done just that.

Jordan Gaines Lewis, Neuroscience Doctoral Candidate, Pennsylvania State University

HEALTH CHECK: CAN I EXERCISE WHILE GETTING OVER A BUG?

As we move into winter, the cold mornings, dark evenings and rain tend to bring out the best excuses to miss a session at the gym or run around the park.

But if you’re feeling tired and run down, can exercise actually make you sick? And should you wait until you’ve completely recovered before putting those runners back on?

Like many things in life, moderation and common sense are key. If your symptoms are above the neck – a runny nose, nasal congestion and a sore throat – you’ll still be able to manage a workout, though at a lighter-than-normal level.

The human body is constantly under attack from bacteria, viruses and fungi that encourage an infection. The common cold is the most common type of infectionworldwide, with most adults succumbing to at least two to three colds a year. Thankfully, most people’s immune system helps to protect them.

But exercise can both help and hinder our immune system. People who perform moderate exercise regularly catch fewer colds than those who are either inactive or perform high-intensity or long-duration exercise. So, a little bit of exercise is good, but too much may be bad.

THE BODY’S RESPONSE TO EXERCISE

Simply speaking, the body’s response to a one-off workout is similar to being injured or fighting off an infection. Inflammation increases the blood levels of different parts of the immune system, providing us with a positive “boost” to help restore the body back to its normal state.

This boost doesn’t last much longer than a few hours before returning to pre-exercise levels. But when repeated regularly, and with sufficient rest in between, each bout of exercise improves immune function that accumulatively leads to a 20-60% reduced risk of infection.

In contrast, athletes and heavy trainers who regularly perform either very intense and/or long-duration exercise are two- to six-times more likely to get sore throats and flu-like symptoms than the rest of the population.

This is most likely caused by the exercise also triggering “stress hormones”. Using the inflammation analogy above, imagine you were constantly injured; this depresses some of the many functions of our immune system and thereby limits recovery back to normal.

WHAT ELSE I SHOULD KNOW?

It’s not all about the exercise. Many of the accompanying behaviours associated with people being moderately or highly active could also explain some of the changes.

Those training too much, including athletes, might not be taking enough care of their diet, or could be suffering from impaired sleep or encountering raised levels of mental stress.

Swap your training for some R&R if your symptoms are below the neck or you have a fever, muscle aches or widespread fatigue. | Photo Credit: highwaysagency/Flickr, CC BY 

At the other end of the scale, those beginning an exercise regime might be making positive changes to all the above.

Diet, sleep, mental stress, poor hygiene and contact with other infected people (large crowds, mass transport such as planes, trains and buses) are all known to influence immune function.

While you may have seen adverts claiming that supplement X can improve your immune function and protect against infection (think probiotics, green tea or berry extract), none appear to provide the same benefit as a healthy, well-fed and active individual.

However, something you can do is keep well-hydrated during your workout. If that comes through the use of a sports drink, it may not be a bad thing – taking in some carbohydrate doesn’t only keep your blood sugar steady, it also lowers the stress hormone response that could take the edge off any immune function depression during recovery from exercise.

WHO BENEFITS?

The good news is that no matter whether younger or older, male or female, or the type of activity you do (gym, aqua-aerobics, playing a sport, gardening, dog-walking, being intimate with your partner, and so on), at least 20 minutes of something that gets you breathing harder and your heart beating faster should provide the same benefit.

Although most of the research conducted and guidelines tend to promote cardio exercise, the limited research looking at lifting weights (resistance exercise) suggests a similar benefit to immune function and therefore reduced risk of infection.

WHEN SHOULD I NOT EXERCISE?

Well, you should probably swap your training for some R&R if your symptoms are below the neck (chest congestion, cough, stomach problems such as vomiting or diarrhoea) or you have a fever, muscle aches or widespread fatigue.

Similarly, if symptoms get worse with exercise, stop and rest, and if they continue beyond a few days, make an appointment with a doctor. Remember, you can always restart your routine gradually when you’re feeling better.

THE BOTTOM LINE

Where exercise is concerned, if you want to prevent infections it’s better to be fitter and exercise most days of the week, while making sure you rest and recuperate sufficiently.

As long as you only have mild symptoms above the neck (runny nose, nasal congestion or sore throat), there’s no need for these to be your excuse from meeting up with your friends at the gym.

But don’t think that your workout alone equals a healthy lifestyle. Don’t neglect a varied and balanced diet, good sleep and hygiene habits, and your psychological and social well-being.

Toby Mündel, Senior Lecturer, School of Sport and Exercise, Massey University

A DARK NIGHT IS GOOD FOR YOUR HEALTH

Today most people do not get enough sleep. The Centers for Disease Control and Prevention (CDC) has called insufficient sleep an epidemic. While we are finally paying attention to the importance of sleep, the need for dark is still mostly ignored.

That’s right. Dark. Your body needs it too.

Being exposed to regular patterns of light and dark regulates our circadian rhythm. Disruption of this rhythm may increase the risk of developing some health conditions including obesity, diabetes and breast cancer

LIGHT REGULATES OUR SLEEP AND WAKE PATTERNS

The physiological processes that control the daily cycle of sleep and wake, hunger, activity levels, body temperature, melatonin level in the blood, and many other physiological traits are called the endogenous circadian rhythm.

On its own, the endogenous circadian rhythm is nearly, but not exactly, 24 hours. Our bodies rely on the Sun to reset this cycle and keep it at precisely 24 hours, the length of our days. The light – and the dark – are important signals for the cycle. This circadian rhythm has developed over three billion years as life evolved on Earth in the context of the Sun’s day/night cycle. It is built deeply into our genetic makeup.

During the night, in the dark, body temperature drops, metabolism slows, and the hormone melatonin rises dramatically. When the Sun comes up in the morning, melatonin has already started falling, and you wake up. This natural physiological transition into and out of night is of ancient origin, and melatonin is crucial for the process to proceed as it should.

If you were to put someone in a dark cave with no time cues at all, the cycle will last about 24 hours, but not exactly. Without time cues like those from the Sun, eventually that person would become out of sync with people outside. In fact many profoundly blind people, who cannot perceive light, must cope with this de-synchronization in their daily lives.

WHAT DOES YOUR BODY DO IN THE DARK?

Many things happen to our bodies during the dark. Levels of the hormone leptin, which helps control hunger, go up. High levels of leptin mean we do not feel hungry while low levels make us hungry.

Why does leptin go up in the dark? Since we evolved without artificial light at night, one theory holds that leptin goes up at night because it would be good to not be hungry during the night, rather than needing to forage in the dark and possibly get into trouble.

This fasting that should happen every night, and why we call the first meal in the morning “breakfast.” Experiments in human beings have shown that sleep disruption and turning on lights lowers leptin levels which makes people hungry in the middle of the night.

In the last decade or two it has become clear that the genes which control the endogenous circadian rhythm (the “clock genes”) also control a large part of our entire genome including genes for metabolism (how we process the food we eat), DNA damage response (how we are protected from toxic chemicals and radiation), and cell cycle regulation and hormone production (how our cells and tissues grow).

Light at night disrupts these processes. The changes that result from exposure to electric light at night have biological connections to disease and conditions that are common in the modern world today including obesity, diabetes, cancer and depression.

BLUE LIGHT, RED LIGHT, NO LIGHT

Not all light is the same – some kinds of light make you more alert and more awake, and others have less of an effect.

Light from the Sun is strong in blue, short wavelength light, although it includes all other colors as well. That’s important in the morning when we need to be alert and awake. But when it comes in the evening or during the night, it fools the body into thinking it’s daytime. We now know that this bright blue light has the strongest effect on lowering melatonin during the night.

Your tablet, phone, computer or compact fluorescent lamp (CFL) all emit this kind of blue light. So using these devices in the evening can prevent that primordial physiological transition to night from occurring. This makes it harder to sleep and might also increase the longer term risk of ill-health.

Other kinds of light, like dimmer long wavelength yellow and red light, have very little effect on this transition. This is the kind of light from a campfire or a candle; even the old fashioned incandescent light bulb is dimmer and redder than the new CFL.

Only in the last 20 years have we acquired a basic biological understanding of how the eye’s retina tells the circadian system it is daytime. Now we know that blue, short wave-length light is captured by the newly discovered photopigment melanopsin in the retina, and that when blue light stops, we start our physiological transition to nighttime mode.

ELECTRICITY CHANGED THE WAY WE SLEEP

Before electricity, people experienced bright, full-spectrum days of sunlight and dark nights. We slept in a different way than we do now. The dark lasted about twelve hours and during this time people slept for eight or nine hours in two separate bouts, and were awake, but in the dark, for another three or four hours.

Everything changed when electric lighting was invented in the latter part of the 19th century. Since then there has been an ever increasing assault on dark. Outdoor environments are relentlessly lit, and more and more people use computer tablets and smart phones at all hours, bathing their faces in bright blue light at times of day when they should be transitioning to nighttime physiology.

When people get away from the city and its artificial light to go camping, they often notice a marked improvement in their sleep. A recent study has verified this effect.

Today, most of us get too little light during the day and too much at night for our circadian rhythm to function at its best. It is the rare person who sleeps in a completely dark bedroom, and many people get very little sunlight because they work inside all day long.

What can you do for your circadian health? Get bright, blue light in the morning (preferably from the Sun), and use dim, longer wavelength light (more yellow and red like incandescent) in the evening. And sleep in the dark.

This will certainly improve sleep, and may reduce risk of later disease.

Richard G ‘Bugs’ Stevens, Professor, School of Medicine, University of Connecticut

LIPS ARE THE MOST EXPOSED EROGENOUS ZONE, WHICH MAKES KISSING FEEL VERY GOOD

Scientists in the Netherlands have reported that we share about 80m bacteria during a passionate ten-second kiss; a finding that makes puckering up seem cringe-worthy – and downright unsanitary at the start of cold and flu season.

But take heart: we’re more likely to get sick by shaking hands throughout the day than through kissing. And the science behind this behaviour reveals that along with all of those germs, we share plenty of benefits with a partner as well.

Kissing is not all about bacterial exchange or romance. Our first experiences with love and security usually involve lip pressure and stimulation through behaviours that mimic kissing, like nursing or bottle feeding. These early events lay down important neural pathways in a baby’s brain that associate kissing with positive emotions that continue to be important in throughout his life.

Our lips are the body’s most exposed erogenous zone. Unlike in other animals, human lips are uniquely everted, meaning they purse outwardly. They are packed with sensitive nerve endings so even the slightest brush sends a cascade of information to our brains, which can feel very good.

Kissing activates a very large part of the brain associated with sensory information because we’re at work making sense of the experience in order to decide what to do next. Kisses work their magic by setting off a whirlwind of neurotransmitters and hormones through our bodies that influence how we think and feel.

KISSING CODES

If there’s real “chemistry” between two people, a kiss can set the stage for a new romance. A passionate kiss puts two people in very close proximity – nose to nose. We learn about each other by engaging our sense of smell, our taste buds and sense of touch. And through that information all sorts of signals are being sent to our brain informing us about the other person. In fact, the scent of man can provide subconscious clues about his DNA to his partner.

Evolutionary psychologists at the State University of New York at Albany found that 59% of men and 66% of women say they have ended a budding relationshipbecause a kiss didn’t go well. It’s nature’s ultimate litmus test, nudging us to be most attracted to the people that may be the best genetic partners.

Research by Swiss biologist Claus Wedekind found that women are most attracted to the scents of men who carry a different genetic code for their immune system in a region of DNA known as the major histocompatibility complex or MHC.

Scientists suspect that when a couple who carry distinctly different genetics for fighting disease, their children are likely to benefit by having a strong immune system. We may not exactly be thinking about parenthood when we connect with someone at the lips, but kissing provides clues to help us decide whether to take a relationship further. (However, it’s important to add that women who take the birth control pill show the opposite preference toward men with MHC geneticsmost like their own. This suggests that when we are on contraceptives, we may be fooling our bodies in more ways than we realise.)

GETTING HOT UNDER THE COLLAR

Aside from helping us find a great match, kissing has other perks as well. It sets off a cascade of neural impulses that bounce between the brain and the tongue, lips, facial muscles, and skin. Billions of little nerve connections distribute information around the body, producing chemical signals that change the way we feel.

A passionate kiss can spike the neurotransmitter dopamine, which is linked to feelings of craving and desire. Oxytocin, known as the “love hormone,” fosters a sense of closeness and attachment. Adrenaline boosts our heart rate and can make us start sweating as our bodies begin to anticipate what might occur later. Cortisol, known as the stress hormone, also dips to reduce uneasiness. Blood vessels dilate, breathing can deepen, cheeks flush and our pulse quickens.

Kissing fosters the sensations we often describe when we are falling in love. In this way, a kiss can herald in a new romantic relationship. It can also solidify the strong bonds we share with family members and friends. Kisses come in many varieties and are inherently tied to the most meaningful and significant moments of our lives by providing a means to communicate beyond what words can convey.

Science has barely begun to study kissing, despite its obvious evolutionary and personal significance, but what we already know demonstrates that there’s a lot more to going on than meets the eyes – and lips.

Sheril Kirshenbaum, Director of the Energy Poll , University of Texas at Austin