Problems with sleep often show up much earlier than more recognizable symptoms in people who develop Alzheimer's disease, but why? A new study offers a major clue, tied to the toxic build-up of tau protein in the brain that accompanies Alzheimer's. These tau tangles are known to damage brain cells and disrupt communications between them, leading to some of the cognition and memory issues typically associated with Alzheimer's disease. The researchers behind the new study, led by a team from the