I up-voted your comment but to add a little more. Not only is the title very misleading, even the first paragraph is somewhat misleading. It isn't until well in

I up-voted your comment but to add a little more. Not only is the title very misleading, even the first paragraph is somewhat misleading. It isn't until well into the article that you actually get the details of the study result that the title is referencing. So for up to 10 days those who only got 6 hours of sleep per night were "holding their own" and not reporting particularly high levels of sleepiness. It was after 10 days of 6 hours a night that their cognitive performance fell off to resemble that of someone missing 2 nights in a row.