We know pretty well what happens during sleep. Our body is inactive, we lose consciousness, and we fail to respond to things that are happening around us.

We also know a great deal of what takes place in our body during sleep. We know how the muscles relax, how certain vital functions continue, what happens to our circulation, our temperature, and so on.

But how do we go to sleep? What actually takes place that enables us to fall asleep? Strangely enough, the most we can say is that there are a great many theories about this. And so far, it has been impossible to prove whether these theories are right or wrong!

For example, it was once believed that we fell asleep when the blood in our body shifted out of or into an important organ. Well, this theory at least is no longer believed because we now know that no such shift of blood takes place.

Another theory no longer believed is that the chain of nerve cells in our body, which act as pathways in our nervous system, were actually broken, and we then fell asleep.

One possibility was that the impulses to the brain were shut off by our body, and that as a result we were no longer in a “wakeful state.” There are even theories about falling asleep which claim that it is a positive instinct. This means that it’s not just a matter of stopping wakefulness, but a positive process by which the body instinctively puts itself to sleep.

There is a whole group of chemical theories about falling asleep too. These claim that some substance that the body needs to stay awake is used up, and so we go to sleep, and during sleep this substance is replenished Or that certain toxic substances are accumulated when we are awake and these produce sleep.

So here we still have a mystery about one of the most common and important things we do. It’s as if our body knows that we need sleep to restore our tired organs and tissues and in one way or another sees to it that we get this sleep.