Keep your brain sharp by finding your sleep 'sweet spot,' study says

(CNN)You know the story of Goldilocks and the three bears, right? Papa Bear's bed was too hard and Mama Bear's bed too soft, but Goldilocks found Baby Bear's bed to be "just right."

That fable could apply to sleep duration in people as they age as well. Just like Baby Bear, older people who sleep "just right" -- getting roughly six to eight hours of quality shut-eye most nights -- appear to delay cognitive decline and keep their brains sharp, according to a study published Wednesday in the journal Brain.