Why Shift Work and Sleeplessness Lead to Weight Gain and Diabetes

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April 13th, 2012

Studies show that shift work and other sleep disturbances like jet lag can disrupt your body clock and increase the risks of obesity and diabetes. But, until now, researchers haven’t really been sure exactly how these changes affect the body’s metabolism.

To find out, Dr. Orfeu Buxton, an assistant professor in the division of sleep medicine at Harvard Medical School, and his colleagues invited 21 men and women to participate in a study in a controlled laboratory setting, where they would have their sleep-wake cycles purposefully disrupted. Over the course of five weeks, the researchers determined when and how much the participants slept, ate and exercised. Although lab-based studies have previously examined the health effects of interferences with the body’s natural circadian rhythm, most of those trials have lasted only about a week or two.

Buxton, who is also an associate neuroscientist at Brigham and Women’s Hospital, was interested in analyzing the effects on metabolism and diabetes risk of longer-term, or chronic, changes to the circadian clock — such as those experienced by shift workers and frequent travelers.

After an initial period of adequate sleep, in which the men and women spent 10 hours in bed each night, Buxton and his team gradually started to dial back the amount of the participants’ slumber. In addition to getting less sleep, the study volunteers were also asked to go to bed and wake up four hours later each day while in the lab, a technique devised to mimic traveling one east-west time zone per day. Eventually, the participants found themselves sleeping during the day and waking at night, just as shift workers do. “We imposed a disrupted cycle and schedule of activities, from sleeping, waking, eating and fasting that was in misalignment with their endogenous 24-hour circadian clock,” says Buxton. “Nobody would do a night shift as punishing as this.”

What Buxton and his colleagues found, however, was worth the trouble. The resting metabolic rate of the volunteers by the end of the five weeks was 8% lower than where they had started. Over a year, says Buxton, such a slowdown of metabolism could translate into a 10-lb. weight gain if people’s diet and exercise habits remained the same. That could explain why night shift workers tend to gain more weight and have a higher likelihood of obesity than day workers; such weight gain is linked to an increased risk of diabetes and heart disease.

The scientists learned something else interesting about another mechanism that put the disrupted sleepers at higher risk of diabetes: the combination of having their circadian clocks reversed (sleeping during the day and waking at night) and the poorer sleep they got as a result had an effect on their insulin levels. After three weeks in the lab, the participants produced about a third less insulin from the pancreas in response to meals; with less insulin available to break down glucose, blood glucose levels started to rise and three of the 21 volunteers showed high enough levels to qualify them as pre-diabetic. (Fortunately, during the nine day washout period at the end of the study, during which participants were allowed to resume their natural day-night cycles, their glucose levels went back down to normal.)

The findings suggest that circadian disruptions combined with inadequate sleep affect the body differently than does sleep deprivation alone. In previous studies in which volunteers slept less, but maintained their natural sleep-wake cycles, they showed less sensitivity to insulin, but there was no change in the amount of insulin released by the pancreas. In the current study, adding changes to the circadian clock seemed to have a more profound effect on the pancreas. Both pathways can contribute to an increased risk of diabetes, but in different ways, says Buxton. “The body responds to sleep restriction in one way, and circadian disruption combined with sleep restriction in a very different way,” he says.

The findings highlight how important the sleep-wake cycle can be for metabolism and health. “It’s harder to dismiss the [observational] studies and workplace studies that show night work is a health risk,” he says. “We’ve shown unhealthy mechanisms can occur even in healthy subjects, so the time for dismissing night work as a health risk is well past.”

The same is true for jet lag, especially if it’s persistent, such as for pilots and other flight personnel. Buxton is hoping to study pilots in training before they start regularly crossing time zones, to see if the same effects he found in the lab also appear in the real world. In the meantime, it’s worth noting that while much of the attention for preventive health has focused on diet and exercise, sleep is an important part of that equation. “If you’re not getting enough sleep, then it’s hard to find the energy to exercise,” says Buxton. “And if you’re not getting enough sleep, you not only eat more than you need but you tend to make poorer food choices. So in terms of obtaining optimum health, all three pillars — diet, exercise and sleep — are important.”

Alice Park is a writer at TIME. Find her on Twitter at @aliceparkny. You can also continue the discussion on TIME’s Facebook page and on Twitter at @TIME.

Read more: http://healthland.time.com/2012/04/12/why-shift-work-and-sleeplessness-lead-to-weight-gain-and-diabetes/?iid=hl-main-lede#ixzz1rtW8Uj77

Learning how to relax!

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April 10th, 2012

Planned relaxation calms anxiety and helps your body and mind recover from everyday rush and stress. Music, a long soak in the bath, or a walk in the park do the trick for some people, but for others it’s not so easy. If you feel you need help with learning to relax, try a relaxation or meditation class. Your GP and local library will have information about these.

Choose a quiet place where you won’t be interrupted.
Before you start, do a few gentle stretching exercises to relieve muscular tension.
Make yourself comfortable, either sitting or lying down.
Start to breathe slowly and deeply, in a calm and effortless way.
Gently tense, then relax, each part of your body, starting with your feet and working your way up to your face and head.
As you focus on each area, think of warmth, heaviness and relaxation.
Push any distracting thoughts to the back of your mind; imagine them floating away.
Don’t try to relax; simply let go of the tension in your muscles and allow them to become relaxed.
Let your mind go empty. Some people find it helpful to visualise a calm, beautiful place such as a garden or meadow.
Stay like this for about 20 minutes, then take some deep breaths and open your eyes, but stay sitting or lying for a few moments before you get up.

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Practising a regular relaxation routine

It’s important that you make time to practise a thorough routine on a regular basis. There are plenty of resources out there to help you do this – the anxiety section lists just a few.

Relaxation is one of the most effective self-help activities for mental health. It can be a useful addition to any other form of treatment as well as being an effective measure to prevent the development of stress and anxiety, and at the end of the day to help you sleep.

Relaxation exercises can be divided into two broad categories: those for the body and those for the mind. Body-centred exercises also have an effect on the mind. Having a relaxed body may not prevent a constant flow of anxiety-inducing thoughts but it’s a good basis for getting some control of them. So for best results try to combine the two techniques.
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Meet the Active Couch Potato

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April 6th, 2012

Can someone exercise and still be a couch potato? That peculiarly modern question motivated a new study from Finland in which a group of healthy, physically active volunteers donned special shorts that measure muscular activity in the legs. The volunteers then went about their daily lives.

All were diligent exercisers. Some ran. Others lifted weights or played soccer. A few Nordic-walked. On one day during the study, they worked out as usual. On another, they did not exercise.

Throughout, the shorts measured how much they actually moved.

A growing body of science suggests that prolonged inactivity, a practice known more familiarly as sitting a lot, is both widespread and unhealthy. In a representative study published last month in The Archives of Internal Medicine, Australian researchers compared medical records and lifestyle questionnaires for more than 220,0000 Australian adults 45 and older.

They found that the more hours the men and women sat every day, the greater their chance of dying prematurely. Those people who sat more than eight hours a day — which other studies have found is about the amount that a typical American sits — had a 15 percent greater risk of dying during the study’s three-year follow-up period than people who sat for fewer than four hours a day.

That increased risk held true in the Australian study even if the people sitting eight hours a day spent at least part of that day exercising.

But that study and many others examining sitting and health have relied on self-reported measures of physical activity, like questionnaires. A few have used accelerometers to determine how many steps people were taking during the day.

No one, though, had directly studied people’s muscular activity during sitting and exercising, outside the artificial environment of an exercise physiology lab, until the Finnish researchers came up with the idea of embedding flexible electrodes into shorts fabric.

And measurement of muscle activity matters. In earlier studies with animals whose legs were immobilized with casts or traction devices, physiologists noticed swift, dramatic and deleterious changes in the levels of certain enzymes in cells throughout the animals’ bodies that affect fat metabolism and blood sugar regulation. The researchers concluded that the lack of muscular contractions in the animals’ legs had caused a chain of biological reactions that led to the alterations in enzyme production.

In the current Finnish study, after volunteers donned the shorts, the electrodes began constantly tracking contractile activity in the quadriceps and hamstring muscles, two of the largest sets of muscles in the body. The volunteers also completed detailed logs about their activities during the days of the study.

The researchers had hypothesized that they would see considerably less muscular inactivity over all on the days the volunteers exercised, says Taija Juutinen Finni, a professor of kinesiology at the University of Jyvaskyla in Finland, who led the study.

But the results did not turn out that way. There was, in fact, virtually no difference in how much time people spent being couch potatoes on the days when they exercised compared with days when they did not. On nonexercise days, about 72 percent of volunteers’ waking time, or about nine hours, was spent sitting.

When they formally exercised, volunteers used about 13 percent more energy over all than on days they didn’t exercise. But they still sat 68 percent of the time.

Surprisingly, how much people exercised or what kind of exercise they chose did not change sitting time. Whether volunteers worked out for less than an hour or for more than 90 minutes, they spent an equivalent amount of time the rest of the day being mostly torpid physically.

It seems that after exercising, the study authors concluded, people “substitute either lighter and/or sedentary activities.”

David W. Dunstan, a professor at the Baker IDI Heart and Diabetes Institute in Australia, who has studied inactivity and wrote an editorial to accompany the new Australian paper, says he found the study fascinating. By measuring muscular inactivity using electromyography, he says, “the measurement is getting closer to the heart of the sitting problem, that being a problem of muscular disuse.”

Dr. Finni agrees. Although she and her colleagues did not look directly at the downstream biochemical effects of the inactivity, she says, their results suggest that normal exercise, which fills so few hours of even active people’s days, “may not be enough in terms of health.”

Of course, exercise remains valuable, she and Dr. Dunstan are both quick to add. It reduces risks for cardiovascular disease and other conditions and burns calories.

But exercise paired with otherwise unalloyed sitting should be avoided, Dr. Dunstan says. “It is important the general public become more conscious about what they do in their nonexercise time,” he says. Almost everybody, he says, “should look for opportunities to reduce their daily sitting time and move more, more often, throughout the day.”

Can Bicycling Affect a Woman’s Sexual Health?

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April 5th, 2012

Spending time on a bicycle seat, which has been linked to erectile dysfunction in men, may also be a hazard to a woman’s sexual health, a new study shows.

Many women who cycle or take spin classes are familiar with the numbness that sometimes can occur from sitting on a traditional bike seat. Bike seats are designed in such a way that body weight typically rests on the nose of the seat, which can compress nerves and blood vessels in the genital area. In men, this raises the risk of erectile dysfunction, something that has been documented in studies of male police officers on bicycle patrol.

But female cyclists have not been studied as closely. A study by Yale researchers in 2006 found that female cyclists had less genital sensation compared with a control group of female runners. As a result, some scientists believe that female cyclists probably are at similar risk for sexual problems as male riders.

In the latest study, the Yale researchers tried to determine whether there are specific factors that influence soreness and numbness among female riders. Forty-eight women took part in the study, each a consistent rider who cycled a minimum of 10 miles a week, but typically much more.

The women took their personal bikes and saddles into the lab. The researchers mounted the bikes on a stationary machine, and had the riders position their seats and handlebars according to their preference. As the women pedaled, they reported whether they felt soreness, numbness or tingling as a result of sitting on the bike seat, and a device was used to measure sensation in the pelvic floor.

Notably, it was the position of the handlebars that seemed to have the most effect. Women on bikes with handlebars positioned lower than their seats experienced more pressure in an area of soft tissue called the perineum, and had decreased sensation in the pelvic floor.

The researchers found that the lower the handlebars in relation to the saddle, the more a woman has to lean forward, forcing her to put a greater percentage of her body weight on the perineum. This problem is particularly likely to occur when a rider leans forward, flattens her back and puts her hands on the “drop bars” of a road or track bicycle for a more aerodynamic position.

“We’re basically showing that there may be modifiable risk factors associated with female riders,” said Dr. Marsha K. Guess, an author of the study and an assistant professor of obstetrics, gynecology and reproductive sciences at the Yale School of Medicine. “This better positions us to educate riders on safe riding practices that may actually be beneficial to reduction of pressure and lost sensation in the pelvic floor.”

The findings, published online in The Journal of Sexual Medicine, help shed further light on the problems faced by female riders, something that needs more long-term study, said Steven M. Schrader, a scientist at the National Institute for Occupational Safety and Health whose early research helped identify bike seat risks for male police officers on bicycle patrol.

Dr. Schrader said that over the years he has given speeches about his findings to groups of police officers who do bicycle patrol. Afterward, he said, women from the audience sometimes approach him and say, “It’s not just a men’s thing.”

“Women are having issues as well,” Dr. Schrader said.

Dr. Schrader’s research on officers showed that one of the best ways to eliminate or reduce pressure on the perineum is to use a bicycle saddle without a nose. The findings led the institute to recommend that police officers and other workers on bicycles use “no-nose” saddles, which put pressure on the sit bones, rather than the soft tissue of the perineum. Although he hasn’t studied use of the noseless saddles in women, he said he believes women would benefit as well.

“If you don’t put weight there,” he said, “there’s no pressure.”

http://well.blogs.nytimes.com/2012/04/02/can-bicycling-affect-a-womans-sexual-health/?src=me&ref=health#

Can you predict a baby’s sex from the size of the bump?

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April 4th, 2012

The shape of the bump, a difficult labour, or dangling a wedding ring over the belly. All are supposed to predict the sex of a baby. But only one works.

If a pregnant woman has a neat bump that sticks out in front like a netball, then it is a boy. If the weight is more spread out around her middle then it is a girl. Or so they say.

As any mother will tell you, there is no shortage of family members and friends offering folk stories about how to tell the sex of your baby during pregnancy. Even strangers stop pregnant women in the street to pronounce on the sex of their baby based on such “conclusive” signs as the shape of their bump.

Sadly, it is not as simple as that.

Two variables determine the nature of a pregnant woman’s bump. The first is the size of the baby. It is true that on average baby boys weigh more at birth than baby girls, and so this could make the bump for a boy slightly bigger. But this small difference in weight does not change the shape of the bump.

The second is the position of the foetus in the womb. If it has its back alongside the mother’s front this makes her belly stick right out. If the baby’s back is parallel with the mother’s back the result is that the abdomen looks flatter. And as the position the developing baby adopts is not dependent on its sex, it is a myth that the shape indicates whether it is a boy or a girl.

Tall tales

So, if you cannot predict the baby’s sex from the shape of the bump, then how about the other folklore tales? Dangling a wedding ring on a string over the bump and looking to see which way it spins will not reveal the answer, because the foetus can have no impact on how something external moves. Nor is there any evidence that the types of food craved by the mother-to-be are related to the sex of the foetus.

But how about the idea that morning sickness is worse if the woman is expecting a girl? The theory is that if you are carrying a girl you get a double dose of female hormones, and this makes you feel sick. Again this is a myth. Most morning sickness occurs during the first 12 weeks when the developing embryo is very small and the levels of sex-related hormones are low.

The only reliable way of knowing the sex of a baby is medical screening – through ultrasound scanning, amniocentesis or through chorionic villus sampling where a sample of cells is taken from the placenta. The latter two tests are only used to determine the sex if there is a risk of a gender-related problem with the foetus. Ultrasound scans are far more common, but some hospitals have a policy of not telling parents the sex of the baby.

But there is one indication, admittedly rather late on pregnancy, which could give you a clue. For years, midwives have joked during long labours that “If it is difficult it must be a boy”. But it seems there could be some truth in this. An Irish study published in the British Medical Journal examined 8,000 births at a Dublin hospital between 1997 and 2000. The authors found that on average labour lasted longer when delivering a baby boy, and that there were more complications requiring interventions such as caesarian sections.

So if you find yourself in the midst of a difficult labour this could hint that you are having a boy. But remember that these are only average figures and there are plenty of difficult labours with female babies too. And that once labour is finally over, you will find out the sex soon enough.

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Disclaimer
All content within this column is provided for general information only, and should not be treated as a substitute for the medical advice of your own doctor or any other health care professional.