Why we all need a week-end lie inRecovery sleep needed for good health
The week-end lie in may be just what the doctor orders for adults who stay up too late or wake up too early on week days, new research suggests.
But even a 10 hour night in bed may not be enough to overcome the effects of serious sleep loss.
In the study, 159 adults were allowed to sleep for 10 hours for two nights in a row. After this, 142 volunteers were restricted to four hours sleep a night for five consecutive nights. They were then randomised to one to six hours of 'recovery sleep,' ranging from zero hours to 10 hours in bed for one night.
The remaining 17 volunteers spent 10 hours in bed on all nights.
Tests showed that those who were sleep deprived over the five days suffered from reduced attention spans and delayed reaction times. However, these improved after a good 10 hours sleep.
But in those who were severely sleep deprived, even 10 hours sleep was not enough to restore mental alertness.
Dr David F. Dinges, director of the Unit for Experimental Psychiatry at the University of Pennsylvania, said: "The sleep restriction was severe enough that recovery of alertness was not complete following a single night of extended sleep.
"Lifestyles that involve chronic sleep restriction during the workweek and during days off work may result in continuing buildup of sleep pressure and in an increased likelihood of loss of alertness and increased errors."
Some words of caution for those who think the best start to the week-end is a night on the town. The study found that performance and mental alertness fell sharply when five nights of restricted sleep were followed by a night of either no sleep or only two hours of time in bed.
"This highlights the importance of avoiding all-night sleep deprivation following a period of restricted sleep," Dr Dinges said.
"The bottom line is that adequate recovery sleep duration is important for coping with the effects of chronic sleep restriction on the brain," he added.
The findings are published in the journal Sleep.
This article was published on Mon 2 August 2010
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