Sleep. We devote about a third of our lives to it, but how many of us truly comprehend its significance?

Galen, one of the most well-known physicians of the ancient world, proposed more than two thousand years ago that while we are awake, the brain’s juice, or motive force, flows out to all the other parts of the body, animating them but leaving the brain completely dried up. He believed that during sleep, all the moisture that filled the rest of the body would rush back, rehydrating the brain and reviving the mind. Now, this sounds absolutely ridiculous to us, but Galen was merely attempting to explain something about sleep that we all experience on a daily basis. We all understand from personal experience that sleeping helps to clear your mind. Despite the fact that we now understand a lot more about sleep than we did when Galen was alive, we still don’t fully comprehend why it is that sleep, of all of our activities, has the most amazing capacity for mental restorative.

Jeff Iliff is a neuroscientist who studies the brain’s unique functions. In this video he will share will you about some recent research that may provide new information on this topic.