Along with all the other changes that come with age, healthy older people also lose some capacity for sleep, according to a new report published online on July 24th in Current Biology, a Cell Press publication. When asked to stay in bed for 16 hours in the dark each day for several days, younger people get an average of 9 hours of shuteye compared to 7.5 for older people, the researchers report.

The study also found that most healthy people, and young people in particular, don't get as much sleep as they need.

The idea that sleep changes markedly across the life span isn't new. In fact, insomnia is a common complaint among older people. But whether age-related changes in sleep were due to changes in social factors, circadian rhythms, or shifts in an internal "set point" for sleep need or the ability to sleep had remained unresolved.

UC Irvine researchers have found a molecular link between circadian rhythms, our body clock, and metabolism. The discovery reveals new possibilities for the treatment of diabetes, obesity and other related diseases.

Circadian rhythms of 24 hours govern fundamental physiological functions in almost all organisms. The circadian clocks are intrinsic time-tracking systems in our bodies that anticipate environmental changes and adapt themselves to the appropriate time of day.

Disruption of these rhythms can profoundly influence human health and has been linked to metabolic disorders, insomnia, depression, coronary heart diseases and cancer.

One of the reasons people on low-carbohydrate diets may lose weight is that they reduce their intake of fructose, a type of sugar that can be made into body fat quickly, according to a researcher at UT Southwestern Medical Center.

Dr. Elizabeth Parks, associate professor of clinical nutrition and lead author of a study appearing in a current issue of the Journal of Nutrition, said her team's findings suggest that the right type of carbohydrates a person eats may be just as important in weight control as the number of calories a person eats.

Current health guidelines suggest that limiting processed carbohydrates, many of which contain high-fructose corn syrup, may help prevent weight gain, and the new data on fructose clearly support this recommendation.

Livestock manure, left to decompose naturally, emits two particularly potent greenhouse gas emissions (GHGs) – nitrous oxide and methane. According to the Intergovernmental Panel on Climate Change, nitrous oxide warms the atmosphere 310 times more than carbon dioxide, methane does so 21 times more.

Converting livestock manure into a domestic renewable fuel source could lead to a significant reduction in GHGs and generate enough electricity to meet up to three per cent of North America's entire consumption needs, according to research published in the Institute of Physics' Environmental Research Letters.

The paper, 'Cow Power: The Energy and Emissions Benefits of Converting Manure to Biogas', has implications for all countries with livestock as it is the first attempt to outline a procedure for quantifying the national amount of renewable energy that herds of cattle and other livestock can generate and the concomitant GHG emission reductions.

Isoflavones (daidzein, genistein and glycitein), found mainly in soy beans and soy-derived products, are plant-derived compounds with estrogenic effects. While animal studies have linked the high consumption of isoflavones with infertility, there had been little evidence of this effect in humans.

Now research published in the journal Human Reproduction states that men who eat an average of half a serving of soy foods a day have lower concentrations of sperm than men who do not eat soy foods. The association was particularly marked in men who were overweight or obese, the study found.

In the largest study in humans to examine the relationship between semen quality and phytoestrogens (plant compounds that can behave like the hormone, oestrogen), Dr Jorge Chavarro, a research fellow in the department of nutrition at Harvard School of Public Health, Boston, USA, and his colleagues found that men who ate the most soy food had 41 million sperm per millilitre less than men who did not consume soy products. (The "normal" sperm concentration for men ranges between 80-120 million/ml).

According to a study conducted at Washington University School of Medicine in St. Louis, older people who did endurance exercise training for about a year ended up with metabolically much younger hearts. The researchers also showed that by one metabolic measure, women benefited more than men from the training.

The researchers measured heart metabolism in sedentary older people both at rest and during administration of dobutamine, a drug that makes the heart race as if a person were exercising vigorously. At the start of the study, they found that in response to the increased energy demands produced by dobutamine, the hearts of the study subjects didn't increase their uptake of energy in the form of glucose (blood sugar).