It turns out that when mice sleep, their brains go into a dishwasher mode: Their brain cells shrink and the flow of the fluid within the brain (cerebral spinal fluid) increases dramatically. How do we know this and more importantly why should we give a ho0t about fluid in mice brains?
Well, for one thing mice are mammals and similar to humans in many respects. Thus, they are often used as starting points for further human research. In this case, increased flow means that these tiny brains (future Senators) are getting rid of toxins faster during sleep than during waking hours.
Why this happens only during sleep no one knows, but it might be because getting that brain fluid flowing requires a lot of energy and guess what? During waking hours these mice are using their brains to eat and run around on those wheels.
While the flow of cerebral spinal fluid in humans has not been studied yet, it is well known that lack of sleep leads to some bad things including heart attacks, cancer and depression. Also. levels of Beta amyloid are higher during the day than at night when we sleep. Beta amyloid is associated with Alzheimers. So it could be that lack of sleep leads to less time for the brain dishwasher to cleanse us of the Beta amyloid and we end up with Alzheimers.
Another interesting twist on this research, is that maybe Alzheimers patients might benefit from more hours of sleep, which theoretically at least could reduce Beta amyloid levels.
You can be sure that studies will be done soon on humans and, if this is confirmed, new drugs targeting insomnia, especially in Alzheimer patients will be in the wings. Until then, getting at least 8 hours of restful seems like a good idea to me.