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.” The occasional genius like Napoleon may perhaps get on habitually with four hours of sleep each night, and the mother watching by the sick-bed of her child may go for weeks in an emergency with but an hour or two of sleep at intervals, infrequent and irregular. But the sensible division made by Alfred the Great into eight hours for sleep, eight hours for work, eight hours for play, will be as far as possible observed by the right-minded and far-seeing everywhere. FOOTNOTES [5] _Psychological Review_, September, 1896. INSOMNIA AND ITS CAUSES Insomnia reduced to simplest terms is nothing but the inability to sleep. While the causes of insomnia may sometimes be exceedingly complex, ordinarily they are evident both to us and those we love the best. Anything, as we all learn by experience, which accelerates the activity of the mind and increases the congestion of the brain is likely to induce insomnia. Worry, fear, grief, prolonged mental effort, any sort of emotional excitement, social dissipation, the intemperate use of coffee, tea, or alcohol are among the most familiar causes of insomnia. Disturbances of digestion, neuralgic pains, arterial disease, eye-strain, and dental lesions are the hidden causes, oftener than we imagine, of protracted wakefulness. Many of the more obstinate cases of insomnia are due, we know at last through Dr. Upson’s remarkable book,[6] to some dental lesion unsuspected because, as is not uncommon, it is unaccompanied by the ache habitually associated with all the ills to which the teeth are heirs. In my Emmanuel clinic I have had one case of insomnia which, in spite of all an efficient doctor could do for the body and the Emmanuel worker for the mind, persisted until I at last discovered that the sufferer was in immediate need of a dentist, whose threshold, through a morbid fear, he had not crossed in many years. FOOTNOTES [6] _Insomnia and Nerve Strain_, 12. THE VALUE OF DRUGS