Chronic sleep loss, sleep debt dangerous

Humans spend about one-third of their lives asleep, so it's no wonder that we often try to cheat the system by rising early and going to bed late.

Many people think they can make up a sleep debt with one or two good nights of rest on the weekend, but new research from Brigham and Women's Hospital suggests this is impossible.

Scientists studied healthy volunteers in a sleep lab for three weeks. The participants kept a schedule that was similar to an on-call doctor - 33 hours awake, followed by 10 hours of sleep.

On average, this translates to less than six hours of sleep per night. They found that volunteers' reaction times improved after they had a chance to sleep - but this improvement steadily wore off over the course of the day.

In the late hours, people's chronic sleep loss caught up with them and caused them to make more errors.

Researchers say the resulting sleep debt creates a dangerous situation for late-night drivers or those who work overnights in a hospital.

Source: www.wkowtv.com

First gene 'linked to aggressive prostate cancer found'

Scientists have discovered the first gene linked to the aggressive form of prostate cancer, raising hope that doctors will someday be able to predict how the disease will progress.

The cancer is often either slow-growing or aggressive, which has led the two types of the disease to be dubbed the ‘tiger’ and the ‘pussycat’.

The difference can be crucial as many prostate cancer treatments carry with them the risk of serious side-effects, including incontinence and impotence.

However, at the moment there is no way to predict which type a patient will suffer.

Although carrying the newly identified gene does not in itself guarantee that a patients’ cancer will be aggressive, the breakthrough raises hopes that doctors could someday discover a number of genes that would allow them to predict the diseases’ progress accurately.

Dr Jianfeng Xu, from Wake Forest University, in North Carolina, who led the study, said: "This finding addresses one of the most important clinical questions of prostate cancer – the ability at an early stage to distinguish between aggressive and slow-growing disease.

"Although the genetic marker currently has limited clinical utility, we believe it has the potential to one day be used in combination with other genetic markers to predict which men have aggressive prostate cancer at a stage when the disease is still curable."

If identified, men who carry the genes could be encouraged to attend screening at a young age, he and his team believe.

More than 35,000 men a year in Britain develop prostate cancer and around one in three go on to die from the disease.

However, many men have such a slow growing form of the disease that they will in all likelihood die from something else before they ever suffer symptoms of their cancer, posing a treatment dilemma for doctors.

The study, published in the journal Proceedings of the National Academy of Sciences (PNAS), looked at the genetic make-up of 4,849 men with an aggressive form of prostate cancer and 12,205 with a slow-growing form of the disease.

Researchers discovered a genetic defect which makes carriers up to 25 per cent more likely to develop the aggressive form.

Dr Helen Rippon, from The Prostate Cancer Charity, said: “Distinguishing between aggressive and slow growing forms of prostate cancer is probably the most significant challenge facing research into the disease today.

“However, this marker is not informative enough on its own to form the basis of a new, more reliable test – up to 30 per cent of men with a less aggressive cancer also carry it.

“Nevertheless, this study raises hopes that a panel of several genetic markers might one day be established that together can determine a man’s risk of developing aggressive prostate cancer.”

Source: www.telegraph.co.uk

Study Links Soy to Lower Sperm Counts

Eating even small amounts of soy products may cut a man's sperm concentration, a study published online last Thursday in the journal Human Reproduction shows.

Of the 99 men enrolled in the study, those who said they ate the most soy had much lower sperm concentrations than those who reported eating no soy. Soy eaters had, on average, 41 million fewer sperm per milliliter than those who avoided soy products. That association held up after other factors potentially affecting sperm health, such as smoking, alcohol and caffeine intake, age, abstinence time and body mass index were considered.

Still, a man starting with an average sperm count (80 million to 120 million per milliliter) and experiencing such a reduction would measure well above the 20 million that is the minimum count within the normal range, says lead author Jorge Chavarro, a research fellow in the department of nutrition at the Harvard School of Public Health.

Consumption of the study's 15 soy-based foods, from miso soup and tofu to soy burgers, ice cream and energy bars, was low, an average of one serving every other day among the highest-consuming group.

Soy contains isoflavones, which have long been tied to infertility in animal studies.

The study is the largest to look at soy's effect on human male fertility; its findings conflict with those of previous studies, one of which found no relationship between the two and another that found soy consumption actually boosted sperm counts.

Given those conflicts, Chavarro says, "I think there is not enough evidence to reach any strong conclusion or advise men one way or the other on whether soy foods can affect their fertility."

Source: www.washingtonpost.com

Hour's exercise 'to lose weight'

Women who want to lose weight - and keep it off - need to be exercising for almost an hour, five days a week, according to US experts.

The University of Pittsburgh study found the 55-minute regime was the minimum needed to maintain a 10% drop in weight.

Only a quarter of the 200 women in the study managed to lose this amount.

A UK expert said it was clear that regular moderate exercise was the way to lose weight, and keep it off.

Approximately two-thirds of adults in the UK are overweight or obese, with some estimates suggesting this could rise to nine in ten by 2050.

Research points to a combination of exercise and calorie control as having the best chance of success in weight loss - although the majority of people who attempt these diets fail to keep the weight off.

The latest research, published in the Archives of Internal Medicine journal, confirms that plenty of exercise is a key ingredient of success.

The Pittsburgh researchers looked at a group of overweight and obese women over a four year period.

They were all told to eat between 1,200 and 1,500 calories a day, and split into four different exercise programmes, varying the intensity and amount of exercise carried out.

After six months, women in all four groups had lost up to 10% of their body weight - but most could not keep this going.

The women who did maintain the 10% loss were those who reported doing more exercise, on average 275 minutes per week.

Hour target

In the UK, everyone is encouraged to manage at least 30 minutes of moderate exercise five days a week, but scientists say that people wanting to maintain weight loss need much more.

Professor Paul Gately, a specialist in exercise and obesity, from Leeds Metropolitan University, said: "This study is excellent - it's the best evidence that this higher level of exercise is needed.

"Thirty minutes a day is good for general health, but if you want to lose weight, you need to be doing more, and if you want to sustain weight loss, you need to be doing even more than that.

"In this country, between an hour and 90 minutes of exercise a day is the recommended level for maintaining weight loss."

He said that "moderate" exercise covered anything that made you slightly breathless, from brisk walking to gardening.

Some US researchers have been looking at novel ways to increase the level of activity among those with "couch potato" lifestyles.

Dr James Levine is helping develop the "Walkstation", a computer terminal with a treadmill instead of a chair.

Writing in the same journal, he said: "Sitting at one's desk uses barely any more calories than staying in bed, but walking at 1mph while working increases caloric expenditure by approximately 125 calories an hour."

Source: news.bbc.co.uk