If you only got six hours' shut eye last night, there is no need (lose) sleep over it.
Scientists say that though it is (wide) believed that we need eight hours of sleep a night, six to seven hours is the natural amount.
Advising short-sleepers to rest easy, the US researchers say, (have) important implications (暗示，含义) for the idea that we need to take sleeping pills because sleep has been reduced from (it) natural level by the widespread use of electricity, TV, the Internet and so on.
The lead author of a study, Ghandi, said: "There's the (expect) that we should all be sleeping for eight or nine hours a night, and if we took away modern technology, we would be sleeping more. But now, for the first time, we are showing that's not truth."
Most of those were studied slept for less than seven hours a night, with the average amount just six hours and 25 minutes. This is much less than the eight hours often (recommend) in western societies.
Despite this, the people studied were in good health, lower rates of obesity (肥胖症), better blood pressure and (healthy) hearts than people in industrialised societies. They were also fitter.
