As anyone who has unwittingly drifted off at their desk will know — tiredness can really creep up on you when you least need it.

But a new study is offering some good news: It claims to prove that we can bank sleep — and store it up in advance of a tiring event.

Researchers in the U.S. invited a group of volunteers to adjust their sleep patterns so the effect could be monitored.

For a week, one half of the group were allowed extra sleep, while the others were told to keep their sleeping patterns the same.

Then, the following week, they were all sleep-deprived.



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