The Guardian: Brendan Lucey, MD, associate professor of neurology and director of the Washington University Sleep Medicine Center, speaks about his new study.

There’s an association between less than five and a half hours’ sleep and, more surprisingly, more than seven and a half hours’ sleep and reduced cognitive performance for older adults.

So how much is right for the over-75s? The “sweet spot” is somewhere in the middle range, between five and a half and seven and a half hours’ kip.

What else is associated with cognitive decline in older people? Alzheimer’s is the main cause, contributing to around 70% of dementia cases. “It’s been challenging to determine how sleep and different stages of Alzheimer’s disease are related,” said Lucey. “But that’s what you need to know to start designing interventions.”

Get the full story at theguardian.com.