JOIN USA weekend lie-in doesn't make up for week's lost sleep: Study
Researchers at the Penn State College of Medicine in Pennsylvania found that performance deteriorates when sleep is regularly restricted to six hours per night -- and does not improve after two nights of "recovery" sleep.
While having a lie-in helps people feel a bit more clear-headed, they are still slow and clumsy, the Daily Mail reported.
For the study, the researchers monitored young men and women who spent 13 consecutive nights in a sleep lab.
They slept eight hours per night for the first four nights. After that, their sleep was restricted to six hours per night for six nights, followed by three "recovery nights" of ten hours' sleep.
Lead researcher Dr Alexandros Vgontzas said: "After one work week of mild sleep deprivation, two recovery nights were adequate in improving sleepiness but not performance.
"The usual practice of extending sleep during the weekend after a busy work week associated with mild sleep loss is not adequate in reversing the cumulative effects on cognitive function resulting from this mild sleep deprivation."
But there is some good news -- at least for men who find it hard to get out of bed at the weekend.
The research shows that they are less able to cope with lack of sleep than the fairer sex -- meaning that if anyone deserves a late start in the morning, they do.
This could be because slow-wave, or "deep sleep", benefits women more than men, the researchers told the annual conference of the Associated Professional Sleep Societies.
Dr Vgontzas added: "In women, but not in men, deep sleep appeared to have a protective effect. Women with a higher amount of deep sleep can handle better the effects of one work week of mild sleep deprivation, and their recovery is more complete after two nights of extended sleep."
But women should not give up their lie-ins without a fight. A previous study, conducted by Warwick University and University College London, concluded that lack of sleep could be linked to heart problems in women.