Jeff Iliff at TEDMED 2014 One more reason to get a good night's sleep

summary

     In average, people spend a third of their life doing nothing but sleeping. It is an instinct that everyone knows how to do and it is sort of daily routine to all of us. We need a good night's sleep; however, do any of us really understand what it is all about?

     Two thousand years ago, Galen stated that our brain's motive force, which is called juice, would flow out to the other parts of the body, leaving the brain all dried up while we are awake, and he thought that when we sleep, all this moisture that filled the rest of the body would come rushing back, refresh the brain and the mind.

     Thanks to the modern technology, we have a chance to unveil the mystery of how human bodies work.

     The first problem that every organ must solve is a continuous supply of nutrients to fuel all those cells of the body. Now, just as every cell requires nutrients to fuel it, every cell also produces waste as a byproduct, and the clearance of that waste is the second basic problem that each organ has to solve.

      Not like lymphatic system, our brain have a different way.

     The brain has this large pool of clean, clear fluid called cerebrospinal fluid. We call it the CSF. The CSF fills the space that surrounds the brain, and wastes from inside the brain make their way out to the CSF, which gets dumped, along with the waste, into the blood.

     Furthermore, when the brain is awake and is at its most busy, it puts off clearing away the waste from the spaces between its cells until later, and then, when it goes to sleep and doesn't have to be as busy, it shifts into a kind of cleaning mode to clear away the waste from the spaces between its cells, the waste that's accumulated throughout the day.