Trump admits he only sleeps for four hours.

Thatcher famously only got half normal sleep. She ended with Alzheimer's. It is not automatically a correlation, given the vagaries of "current medical understanding on the subject", but:

There is a blood brain barrier, and veins in the brain differ by being concentric tubes. Inner caries blood, the outer is constricted during waking hours, but during sleep it expands and carries fluid to flush out all the by-products of the burning of fat/sugars etc with oxygen. Principle of that detritus are prions. Now you may make the connection.

Not a given, but a gamble. Reagan? Wilson?

you heard it here- One more reason to get a good night's sleep TED talk.