There is a “bi-directional” link between sleep disruptions and the dementia process. Dementia often causes sleep problems; poor sleep, in turn, may speed declines in memory and other mental skills. According to Winer, animal research suggests that deep sleep helps “clear” the brain of the amyloid-beta proteins that build up in people with dementia. Older people are famously prone to being “early to bed, early to rise.” They may also sleep a little less than they used to in their younger days. And that may be fine. Similar vicious cycles may be at work with other diseases, too.