If you are planning a late night, you might be able to avoid the effects of too little rest, research suggests.
Scientists claim it's possible to "stockpile" sleep in advance to help you cope.
They reckon an extra two hours a night for a short period before going without could help millions cope with busy social lives or changes in shift patterns at work.
It had been thought the only way to get over sleep deprivation was to catch up afterwards.
But the study by researchers at the University of Calgary in Canada suggests that getting extra sleep before a late night is just as good at improving physical performance, brain function and memory recall.