Weekend Lie-in could be vital for good health says research

Those extra hours in bed may be necessary to help busy folk recover from lost sleep Monday to Friday.

Tests on a group of volunteers showed that lying in provides an antidote to the effects of days of sleep deprivation.

But one or two hours might not be enough, researchers found. For serious sleep loss, even 10 hours in bed may be insufficient to cancel out the negative effects.

Study leader Dr David Dinges 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.

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

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

In the study by the Division of Sleep and Chronobiology at the University of Pennsylvania School of Medicine in Philadelphia - 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 made up a comparison group who spent 10 hours in bed every night.

Every two hours from 8am each morning, volunteers were given a 30 minute series of neuro-behavioral tests of mental alertness and wakefulness.

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 for attention lapses, poor reaction times, and fatigue.

"Recovery of alertness dimensions was remarkably dependent on the duration of the recovery time in bed," said Dr Dinges, whose findings are published in the journal Sleep.