“We have a specific sleep signature right now that seems to help us better understand where you may sit on the Alzheimer’s disease risk trajectory in the future,” sleep scientist Matthew Walker tells NPR.

MATTHEW WALKER: We are now learning that there is a significant relationship between sleep and dementia, particularly Alzheimer’s disease.

HAMILTON: Walker says the strongest evidence involves deep sleep. That’s a time when dreams are rare, body temperature drops and the brain produces slow, rhythmic electrical waves.

WALKER: There is something about this deep sleep that is helping protect you against amyloid buildup in the brain.