Because of statements like:
> people who sleep between 6.5 hr. and 7.5 hr. a night, live the longest, are happier and most productive
O RLY? Time for another basic primer on causation vs. correlation.
> people who sleep between 6.5 hr. and 7.5 hr. a night, live the longest, are happier and most productive
O RLY? Time for another basic primer on causation vs. correlation.
Note that I am not saying that the result is fact, just that there is science to indicate that things are not as simple as they may appear to people that dismiss the whole thing as "pseudo science".
I'm afraid "science" is quite a bit more complicated than you seem to believe.
One of its most basic tenets is that extraordinary claims require extraordinary evidence. One study is not enough to prove the assertion that people who sleep for 6.5 to 7.5 hours a night are the happiest.