Sleep, however we account for it, is “the resting time of consciousness.”[2] To be sure, there is no absolute arrest of brain activity. There is always, even in the soundest sleep, some cerebral activity.[3] We dream. We have nightmares. We sometimes work out problems in our sleep which have defied our every waking effort. There is on record one instance of a college student who got up at three o’clock to solve successfully, while sound asleep, a problem he could not work out at all before he went to bed. There is another instance well attested of a British consul in Syria who, after tearing up letter after letter which he wrote to a Lebanon emir, went to sleep in sheer despair, only to find when he awoke in the morning, that he had written an elaborate letter which in every way satisfied the multitudinous demands of Arabic diplomacy insistent to the last on all the niceties of Oriental etiquette.[4]
Byron was right. Sleep is neither life nor death. It is a world apart.
Sleep has its own world,
A boundary between the things misnamed
Death and Existence; sleep has its own world.
Consciousness may be suspended. But the cortical centres are frequently as active when we are asleep as when awake. The attention can be maintained with such unbroken steadiness as to awake some persons with the exactness of an alarm clock on the very minute, even though for purposes of deception the hands of the clock may have been set back without their knowledge. The motor centres can be counted on so confidently that they will drive the somnambulist with the accuracy of a trained chauffeur to his appointed destination. Sleep is, therefore, nothing more than a temporary suspension of a portion of the brain’s activity.
THE NECESSITY OF SLEEP
But that suspension is an absolute necessity to health of mind and body. Men have been known to go for forty days without nourishment and retain unimpaired all the mental faculties. No man goes for even three days and nights without sleep except he pay a penalty in mental equipoise, and death itself is apt to bring his misery to an end, it is claimed, in five sleepless nights and days. Professors Patrick and Gilbert of the University of Iowa found, some years ago, that in certain cases there were after two nights of complete wakefulness hallucinations, loss of attention, inability to remember, and unmistakable evidences both of mental disorganisation and physical depression.[5] In Kipling’s story, tragically true to life, Hummil died after eighty-four hours of unrelieved insomnia, and the author’s closing words would seem to indicate that madness overtook him at the last: “In the staring eyes was written terror beyond expression of any pain.”