A study in the May 1 issue of the journal Sleep describes how changes in sleep that occur over a five-year period in late middle age affect cognitive function in later life. The findings suggest that women and men who begin sleeping more or less than 6 to 8 hours per night are subject to an accelerated cognitive decline that is equivalent to four to seven years of aging.

Read more http://www.eurekalert.org/pub_releases/2011-05/aaos-aci042711.php