Manasseina describes also her own results in the book, including the experiments on sleep deprivation, and she concludes that sleep is necessary as “nutrition and reconstitution of the (cerebral) tissue“. She concludes this chapter enhancing the importance of sleep as a particular state of the brain activity, rather than the absence of activity, as it was commonly viewed at the time. This was a remarkable intuition, considering that the electroencephalogram did not exist yet.
“At the same time we must remember that sleep is not an absolute arrest of cerebral activity. The brain remains partially active, only sleeping in so far as it is the anatomical basis of full consciousness. Byron was certainly right when he said that our life is composed of two distinct existences, for sleep is a world apart:
“Our life is twofold; sleep has its own world,
A boundary between the things misnamed
Death and Existence: sleep has its own world.” (In italics in original)
It is necessary to study seriously and fundamentally this part of life, for on that study depends the solution of other essential questions of our existence.”