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WHY SLEEP?

© Kerrin Leon White

An article just published in the latest issue of the scientific journal, Sleep, (2000; 23:7:959-966), caught my interest and left me wanting to share it with lay readers, who might find the original hard to follow. The article, written by Joel H. Bennington, PhD, of the Department of Biology, Saint Bonaventure University, is entitled: "Sleep Homeostasis and the Function of Sleep."

The issue might be paraphrased in one clipped question: "Why sleep?" The less than satisfying answer still boils down to "Nobody knows!" No one of several competing theories stands out as clear front-runner for the truth--though some do seem to be lagging behind!

Since there has yet to occur any breakthrough or even significant new addition to our knowledge about the matter, is there anything in this discussion to interest the casual reader?

Its relevance to all of us lies in the central assumption--supported by considerable evidence--that sleep does have a function, and in fact represents a need, a process necessary for the normal functioning of the individual.

"Isn't this obvious?" some readers might ask--but maybe without knowing how to defend that claim. Yet many people talk and act as if they don't believe that "obvious"--and important--point.

As a physician active on the Internet, with some pretense of expertise in sleep (at least, sleep apnea, with which I have a long and personal acquaintance!), I get a good deal of e-mail asking questions about a wide range of issues around sleep.

What sometimes emerges from these interchanges is the notion that sleep is a waste of time, that the less you sleep the more time you have to accomplish useful things, and that you can make do with less than the "normal" amount of sleep if you just exert your will to do so.

This is, I feel, wishful thinking, especially among students, who like to think that they can attend school full-time, work part-time, engage in a strenuous social and recreational life, and still find ample time to study late into the night, without giving up anything in the way of full functioning. This is typical of adolescent grandiosity, but the fallacy gains importance when, as often happens, it persists into the purportedly greater "wisdom" of adults.

How does this point relate to Dr. Benington's review article? It relates in the way his article refers to sleep homeostasis as a key fact to consider in speculating about the function of sleep.

However, homeostasis is a term which may lose the average reader--though it means nothing more complicated than the body's tendency to compensate for disturbances--such as lack of food, water or sleep--with changes designed to restore the balance--that is with eating, drinking, or sleeping. These compensating changes are associated with the sense of motivational "drives" such as hunger, thirst, and sleepiness.