Weekend lie-in 'vital antidote to working stress'

Tests on volunteers appear to show that those extra hours in bed may be necessary to help busy folk recover from lost sleep Monday to Friday.

But one or two hours might not be enough. Even 10 hours in bed may be insufficient to cancel out the negative effects.

Study leader Dr David Dinges, who heads the Division of Sleep and Chronobiology at the University of Pennsylvania School of Medicine in Philadelphia, said: "The additional hour or two of sleep in the morning after a period of chronic partial sleep loss has genuine benefits for continued recovery of behavioural alertness.

"The bottom line is that adequate recovery-sleep duration is important for coping with the effects of chronic sleep restriction on the brain."

Inadequate sleep is known to impair the ability to think, handle stress, maintain a healthy immune system, and keep emotions in check.

When people lose sleep, their concentration drops and they suffer memory lapses. The brain falls into "rigid" thought patterns, making decision making and problem solving difficult.

It can have a big impact on work performance, yet stress and long working hours frequently mean people in busy jobs get too little sleep.

Experts say most people need between 7.5 and nine hours of sleep a night, although some get by on less and others need more.

In the study – the largest sleep deprivation experiment ever conducted – 142 adults with an average age of 30 were restricted to four hours in bed from 4am to 8am for five consecutive nights.

They were then randomly assigned to one of six doses of a single night's "recovery" sleep ranging from zero to 10 hours.

Another 17 "control" participants spent 10 hours in bed every night.

Over the course of the five days, the test performance of the sleep deprived volunteers was consistently worse than that of the well-rested control group.

One night of recovery sleep led to improvements as the sleep doses increased. But even after 10 hours in bed, sleep-restricted participants still had worse scores than the control group.

Previous research by Dr Dinges found that even moderate sleep restriction can seriously impair neurobehavioral functions. Sleeping for six hours or less a night for two weeks led to performance deficits equivalent to staying awake for 48 hours.

GENE SWITCH MAY HELP TREAT CANCER

A discovery that makes it possible to speed up or slow down the growth of blood vessels could yield new treatments for cancer and heart disease.

Scientists in the US found a "switch" made from a short strand of genetic material that plays a crucial role in blood vessel renewal.

They also produced a molecule that can turn it

off, allowing them to press either the accelerator or brake.

Tumours use the same trick, called angiogenesis to give themselves blood vessels that fuel their growth.