What Is Sleep

3. What Is Sleep?

Our foremost sleep scientists have not settled upon an answer to this question. Obviously sleep is loss of consciousness. But what more is there to it? Why should awareness cease? Does not the brain conduct millions of processes continuously even though it has lapsed into unconsciousness?

Sleep scientists have several theories about what sleep is: One is that the neurons become fatigued and simply lower their activities below the level required for consciousness. Another is that the brain inhibits the reticular activating system.

Another theory is that the brain and nervous system operate on nerve energy, a form of electricity. The body, like an electric car, needs to be recharged at night. Sleep is a partial shutdown for recharging.

3.1 Why Should We Sleep At All?

Dr. Nathaniel L. Kleitman of the University of Chicago has concluded that the body generates nerve energy during sleep and that we sleep for this purpose. All other writers and researchers observe and attest to the restorative powers of sleep but do not suggest the physiological basis for these powers.

Among the texts you have is Better Sleep for a Better Life. This book details man particulars on the whyfore and conditions of sleep. We shall not repeat them here. We sleep because the brain requires, we may presume, a state of unconsciousness for the regeneration of nervous energy.

3.2 The Purpose of Sleep

Experiments with electrosleep indicate that the body generates low-level electricity during sleep. So far, researchers have not discovered where the body stores its electricity.

The primary purpose of sleep seems to be the generation of nerve energy. That seems to be the only reasonable explanation, for most researchers agree that sleep is a restorative. The vitality of the organism is restored under the condition of sleep.

Guyton’s Textbook of Medical Physiology takes the position that sleep occurs because of neuronal fatigue. He says that, when one of the millions of parallel neurons in the feedback circuits falls out of activity, the lowered level of excitability of other neurons starts a chain of depressed activity that results in sleep. More particularly, wakefulness is attributed to the excitability of the reticular activating system, which is, a network of neurons, and sleep is attributed to lack of excitability.

Perhaps this does chronicle the mechanism of sleep, but other passages in the same physiology text appear to negate this position. Nerves or neurons perform twenty-four hours daily, just as the heart muscles. They need no rest or sleep. Only a certain part of the brain needs sleep, for the brain and nervous system continue to conduct millions of processes under the condition of sleep.

It appears that the faculty of wakefulness must cease in sleep and that neurons are only partially inactivated. Moreover, it is known that the brain is active during sleep except for those areas of the brain involved with consciousness. Some body processes are conducted more vigorously in sleep than in wakefulness.

Guyton is unable to explain what causes fatigue in neurons since, in theory, they are not subject to fatigue. He says: “We still need to explain the cause of fatigue of neurons after 16 hours of wakefulness and their recovery of excitability after 8 hours of sleep.” Perhaps the depletion of nerve energy causes fatigue in neurons.

Sleep is primarily for the purpose of generating nerve energy or low-level electricity. Many other beneficial purposes are also served during sleep. The physiological rest obtained during sleep is extraordinarily valuable. During the prolonged rest of sleep, the body restocks its cells and organs with fuel, replaces cells that have lost their vitality and rids itself of extraordinary toxins that may have been uneliminated the previous day. Thus, the value of sleep is manifold.

The benefits of sleep may be chronicled as follows:

1. The regeneration of nerve energy;
2. Refueling the liver and cells with glycogen;
3. Destruction of old cells and replacement with new cells (Multiplication of cells occurs during sleep at a rate of more than twice that during waking hours); and
4. The body expels more debris and wastes during sleep and rest than when active.

Undoubtedly there are other benefits of sleep, but these ire the salient ones. For instance, the body uses less nerve ‘energy and generates less waste when asleep.

3.3 Sleep As an Essential of Life

We can accept sleep as being absolutely necessary without question. But, as well, getting enough sleep is an essential of life. It is impossible for a healthy person to oversleep but undersleeping is an evil of our, times—a transgression most of us commit against ourselves.

When we undersleep, not enough nerve energy is generated to meet needs. We use more nerve energy when we are awake longer and generate less with less sleep, other conditions being equal. When our nerve energy is squandered to meet excessive consciously-directed activities, then nerve energy for unconscious body activities is not available. This may mean poorer digestion, impaired elimination and so on—the body must suffer generally.

With adequate sleep enough nerve energy is generated to meet our normal needs. The question of what constitutes adequate sleep and how to best obtain it is very important. The book, Better Sleep for a Better Life treats this subject in depth. In this lesson we’ll endeavor to explore other materials to reinforce the wealth of observations in that book.

3.4 Some Current Views of Sleep

To be sure, the views offered on sleep in texts and books are few and mostly noncommittal to any stance or position. What scientists really know about sleep amounts to very little, and their views or theories are rather timid.

A view of sleep that is interesting is expressed in The Complete Book of Sleep by Diane Hales, a sleep researcher who has haunted many sleep laboratories looking for revelations on the subject. Her observation about sleep is instructive: “We think of sleep as being passive and uniform, but it actually consists of cycles of complex activity. We think our bodies and brains rest during sleep, but in fact our muscles tense, our pulse, temperature and blood pressure rise and fall; we are sexually aroused; our senses evoke a world of sights and sounds. We think that in sleep we shed our fears and feelings, but our personalities set our sleep patterns, and our sleep shapes how we feel and act. We accept sleep as commonplace, yet when we cannot sleep, we yearn for it more fiercely than for the rarest treasure. We are able to go without food or water or companionship more easily than without sleep.”

On the all-important question of what sleep is or why we sleep, Ms. Hales is silent, though the book asks these very questions. One speculation ventured is that nature instituted sleep to keep animals quiescent during darkness so as not to injure themselves; so as to survive the perils of darkness. But a most compelling observation is made by Dr. Allen Rechtschaffen of the University of Chicago. He poses the question: “If sleep doesn’t serve an absolutely vital function, then it’s the biggest mistake the evolutionary process ever made. How could sleep have remained virtually unchanged as a monstrously useless, maladaptive vestige throughout the whole of mammalian evolution while selection has, during the same period of time, been able to achieve all kinds of delicate finely tuned adjustments in the shape of fingers and toes?”

What a good question! To ask the question is to acknowledge that nature does not err and has definite purposes in developing our faculties.

Other observations made by Ms. Hales are worth noting: “But if there is a timeless need for sleep, what is it?

This question remains one of the most perplexing biological riddles. Aristotle thought that we sleep because of cooling of the vapors of the head. Freud thought sleep was a symbolic journey back to the security of the womb. Pavlov thought of it as a conditioned response. Others have argued that we sleep to repair the ravages of the day, or the purge our brains of extraneous information, or to conserve our energy. Sleep may be maintenance time for our bodies or a sort of dress rehearsal for our brains.

“Perhaps none of these explanations is correct. Perhaps they all are, for it may well be that sleep—like waking—has many functions. We may be making an enormous and costly mistake by assuming that our nights are any less significant or complex than our days,” says Ms. Hales.

I have previously cited Dr. Arthur C. Guyton’s text on sleep. Two theories he presents about the mechanism of sleep are worth reviewing. These theories relate to the physiology of going to sleep.

“The first belief is that sleep is a passive process, occurring when the neuronal mechanisms that cause wakefulness become fatigued and therefore succeed to a lower level of activity. The second theory is that active centers in the brain transmit signals into the reticular activating system to inhibit it and thereby produce sleep.”

The primary difference between the two theories is that one assumes that the usual slow wave sleep (delta sleep) results from decreased excitability of the reticular activating system due to fatigue, while the other holds that sleep results from active inhibition.

While Dr. Guyton favors the first of these theories, your instructor favors the second. The brain actively seeks sleep when its nerve energy falls below a certain level.

Another theory of sleep holds that we sleep in order to have dreams, so that our “mental mix” may be sorted out. Cited in support of this theory is the gravely ill effects resulting from denial of REM (rapid eye movement) sleep, that stage of sleep during which dreams are conducted. After a few days without REM sleep, test subjects were depressed, less alert, garrulous and unable to concentrate. In short, they suffered many of the same effects as if they had suffered a big deficit in their “sleep account.”

Simply stated, the brain sleeps in order to regenerate a fund of nerve energy. Nerve energy is the “money of account” for human vitality.