http://www.newsweek.com/poor-sleep-memory-thinking-problems-dementia-1857479

Disrupted sleep in your 30s and 40s can lead to cognitive problems in later life, scientists say.

As of 2014, an estimated 5 million American adults over 65 were living with dementia, according to the U.S. Centers for Disease Control and Prevention. The most common form of dementia, Alzheimer's disease, represents roughly 60 to 80 percent of dementia cases, but the term also describes a range of other conditions characterized by an impaired ability to remember, think and make decisions.