Dr. Fred W. Eastman reports that owing to pressure of work he was recently unable to get more than three or four hours’ sleep out of the twenty-four during a period of many months, and that so far from being hurt by it he gained five pounds.  He says:  “If restoration during sleep is a task so relatively small, the question arises whether, in order to complete restoration, it is necessary for us to spend so much time in sleep as we do.  Perhaps on account of popular opinion and personal habit, we waste much time in this jelly-fish condition that could more profitably be spent in active pursuit of our ambitions.  The answer, of course, depends upon the nature of our occupations.  If there is muscular effort involved, with a correspondingly large amount of waste in the cells and blood, eight hours or more are probably necessary.  But if the work is of a sedentary nature, and mainly of the brain, there is naturally a smaller quantity of accumulated waste, and less time is required for removal.  Many are the instances of great men, past and present, who have lived healthily and worked unceasingly and strenuously on only four or five hours of sleep, or half the laborer’s portion.  Surely we do not suppose that these men were or are physically different from others, but rather that by inclination or necessity they have developed a habit of sleeping intensely for a short period, with resulting gain of time and efficiency.”

[Sidenote:  Determining Your Norm of Efficiency]

So far as this matter of relaxation, rest and sleep is concerned, the rule to follow is obviously this:  Determine accurately by experiment the proper relation between periods of work and periods of rest in your own case, then increase your efficiency by maintaining this relation.

In Denmark they feed cows scientifically.  Day by day they increase the allowance of milk-producing food.  Day by day the yield of milk increases.  At last there comes a day when measurement shows that there is no longer any increase in the production of milk.  They then decrease the food till the output of milk diminishes.  So they determine the normal.

So with you and your hours of work and leisure.  Give more and more time to your business each day until there comes an impairment in the quality of your work.  Stop short of this.  You have found your norm of efficiency.

CHAPTER V

THE SECRET OF MENTAL EFFICIENCY

[Sidenote:  Where Energy Is Stored]

You are called upon to master and conserve the innate energies of your mind.  This means that you must (1) find out where these energies are stored, and (2) learn the conditions that determine their activity.

All past experiences are conserved within us in the form of complexes.  These complexes consist of ideas, emotions and impulses to muscular activity.  By the primary law of association the recall to consciousness of any one of these component elements of a complex brings with it all the rest.