What Makes Me Wake Up in the Morning?
In order to understand this we must realize that we do not sleep in just the same way all through the night. At first we sleep deeply. Now, it is good to sleep deeply. It makes us look well and beautiful, and people seem to have noticed this, for they call the first hours of sleep the “beauty sleep.”
But for some hours after this we sleep less and less deeply. We can easily find this out by noticing exactly how loud a noise is required to wake one up at various times in his sleep. And we find that when a person has had nearly enough sleep he will be wakened by a noise which, a few hours before he would not have noticed.
That is the sort of thing that happens when we wake. We have been sleeping less and less deeply for some time, and our brain has almost awakened of itself. Then there comes a sound or a light, or perhaps we move in bed and feel ourselves moving, and since we are already very nearly awake, the sound or the light or the feeling wakes us up. Of course if we lived out-of-doors, as men did long ago, and as birds do still, light would wake us up. That is what wakes the birds now.
