Mental health articles

Sleep is normal, psychological, not an evidence of the pathological, the diseased. Sleeping and waking are merely different manifestations of normal life-processes. When the organism becomes fatigued as the result of continued stimulation, those stimuli which have exhausted themselves or ceased to act on the organism by reason of their monotony, drop out and are replaced by new ones, until the whole round of stimuli has been gone through. Then the organism ceases to respond to the stimuli and falls asleep.

Organisms, therefore, fall asleep when the threshold for stimulation rises, and waken when the threshold falls. Neither monotony of sensory impressions nor limitation of voluntary movements is necessary for sleep. Sleep likewise does not result from a fatigue of the organism by continued stimulation, but only if the actual stimulus be decreased, either to zero or to the threshold of conscious perception. The motionless states produced in animals by sudden peripheral excitations are not sleep, but a form of hypnosis. If a stimulus is present, but just falls short of producing a sensation, then for the organism it is just as if no stimulus existed at all. It has been shown beyond a doubt, however, that sleep takes place when the peripheral sensations are cut off or greatly diminished. Now it is well known, that the activity of consciousness is maintained by these sensations, which pour in from the eyes, ears, muscles, and the afferent nerves of the skin. When these are cut off or reduced to a minimum, sleep results. The nervous system receives the active energies supplied to it by stimuli of all kinds and is merely a conduction path connecting peripheral organs with the center,—a receptive surface with an afferent organ in combination. The greatest mass of stimuli pouring into the brain comes from the muscles and it is for this reason that a diminution of muscle tonus (or tension) either accompanies or precedes the onset of sleep. Thus the problem of sleep becomes essentially a psycho-biological problem and seemed so promising that I investigated the function of sleep from this standpoint.1 My experiments were performed on animals and also on a series of human subjects, in whom I could check my procedures and thus have the advantage of introspective evidence, a thing manifestly impossible in animals.

The animal experiments on crayfish, frogs, and guinea pigs were undertaken merely to establish the nature  of motionless states in animals, in order to determine whether these were genuine sleep, hypnosis, or states of cerebral inhibition. Thus I was able to trace the mechanism of sleep from animals with a primitive nervous system, up to man. When a crayfish, frog, or guinea pig was thrown suddenly on its back and held in a firm position for a few minutes, it would remain motionless  even  in  a  strained  and uncomfortable attitude for a prolonged period of time after the experimenter’s hold had been released. The entire body would be immobile, the limbs rigid, eyes widely opened, and the reflexes exaggerated. The animal would not move on external stimulation, such as jarring of the table or the flashing of an electric light in the widely opened eyes. In other words the animals were cataleptic, resembling deeply hypnotized human beings.

Tags: psychology, sleep