It may seem counterintuitive, but staying in bed may help you stay trim, say French and US researchers, based on surveys in seven countries, starting in 1992. 'Our analysis shows a clear association between sleep duration and the risk for extra weight or obesity in children,' says Youfa Wang of Johns Hopkins University. 'The risk declined with more sleep.' And Karine Spiegel, of France's Inserm health organisation, says the rise in obesity in the US from the 1950s corresponds with a decrease in sleep. Hormones produced during sleep, grehlin and leptin, help regulate appetite, AFP reports.

Mutation prevents hypertension

As many as 100 million people worldwide have genetic mutations that help keep their blood pressure naturally low, cutting their risk of developing hypertension by 60 per cent, along with that of heart and kidney disease and stroke, say Yale University researchers. The findings may lead to more effective blood-pressure medication. About 2 per cent of the world's population have a mutation in at least one of three genes - the equivalent of natural, blood-pressure medication. The mutations affect how the kidneys handle salt, which regulates blood pressure, Reuters reports.

Mud wrestling the superbugs

US researchers have found anti-microbial minerals in mud that may be able to combat dangerous, antibiotic-resistant superbugs such as methicillin-resistant staphylococcus aureus (MRSA). 'For hundreds of thousands of years, clays have been used for wound-healing and even gastrointestinal problems,' says study co-author Shelley Haydel, of Arizona State University. 'And now we're seeing effectiveness in the lab.' After analysing 20 different clay samples from around the world, the team identified three that appeared to kill or substantially reduce growth among all the tested bacteria, including MRSA, the flesh-eating Mycobacterium ulcerans, E. coli and salmonella, healthday.com reports.

Set the egg timer and go for it

Good news for men who have trouble going the distance: three minutes is quite acceptable for heterosexual intercourse, according to a survey of US and Canadian sex therapists. However, that doesn't include foreplay and is at the lower end of the 'acceptable' range of 3-7 minutes, with up to 13 minutes being 'desirable'. The researchers, from the Penn State Erie research institute, say their survey may help correct some people's 'unrealistic' expectations for sexual performance. Fifteen of the 34 therapists surveyed were men.

North Atlantic natives live longer

Icelanders have the longest life expectancy in the world for men: 79.4 years, says Oloef Gardarsdottir, a spokeswoman for the country's national statistics office, but she has no idea why. Icelandic women's life expectancy of 82.9 years is one of the highest, but less than that of Japanese women, who hold the record with almost 86 years. Iceland has a population of 313,400 and is one of the richest countries in the world per capita, AFP reports.