Right amount of sleep may affect brain age

May 2, 2011 2:24:59 PM PDT
According to a study in the journal sleep, for middle aged adults, sleeping less than six or more than eight hours a night is associated with a decline in brain function.

The magnitude of that mental decline is said to be equal to being four to seven years older.

Scientists say most research has focused on the effects of sleep deprivation on biological systems.

So it's not*fully understood why seven hours is optimal or why sleeping more than eight hours appears to be detrimental.