Some sources of disturbance that clearly belong to exogenous disturbance factors can subsequently lead to psychically conditioned disturbances in falling asleep. One of these is noise.

A disturbance from without can have the effect of an arousal stimulus even to sound sleepers accustomed to noise. The result is an exogenous disturbance to falling asleep. If the person has become accustomed to the noise and if the disturbance stimulus has become anonymous, v no longer seems to be very loud, and hence has lost its disturbing effect, the person falls asleep despite the noise. Sleep, as an active accomplishment by the organism, takes place because it has been practiced (conditioned) for a long time, i.e., it has been learned.

An additional factor in noise as a disturbance factor is the subjective evaluation and the importance ascribed to the source of the noise. The individual reaction prompted by noise varies and can in time change. The disturbing effect of noise is by no means in response to a measurable magnitude or volume of sound. The disturbing effect depends far more on the individual evaluating it. It also depends upon constitutional peculiarities and upon the particular vegetative state of the organism. It especially depends upon the mental attitude toward it

through which it gets the full measure of its disturbance value.

For example, a dog's barking may be registered as such a strong source of disturbance that it triggers a veritable chain of reactions ranging from fury to nervousness. It may be accompanied by heart palpitation and outbreaks of perspiration, physical pain, and ultimately violent aggression against the dog and its owner, but it can quite unsuspectedly vanish if one has come to know the dog owner as an appealing person and to be familiar with the dog's amusing, prankish characteristics. The barking then loses its disturbing quality, and one now knows or rather interprets when the dog is barking from pleasure or because children are playing and bothering him. Imperceptibly the concentration on the noise abates, separate phases of the noise are even ignored because of being freed from obsessively perceiving the noise as a disturbance.

Apart from the responsiveness of the autonomic nervous system, which varies according to its condition, the vegetative reactions to noise are the only reactions that are dependent upon volume. While a healthy sleeper's consciousness can simply shut out a disturbance, the autonomic nervous system is by no means able to disregard "noise as a disturbance factor." It continues to register the irritation subliminally. Its reaction is expressed by a state similar to that of an awake, agitated person in whom the sympathetic nervous system, which functions as the trigger of the autonomic nervous system, dominates (ergotropic state of functioning). Sleep should be synonymous with calm and relaxation for the organism, though, and should be a trophotropic state of functioning.

A sound sleeper sleeps despite noise. However, the autonomic nervous system by no means gets the same recuperation from such sleep as it does from sleep in quiet surroundings. City planners and architects should know and keep this in mind.

Noise as a disturbance factor depends upon the affective content that the disturbance has for the sleeper. In other words, the affective content is the connection conditioned by feeling (emotion) between the stimulus and the recipient of the stimulus. It also depends upon the informational content of the noise.

Young mothers, for example, manifest a selective sensitivity to noise in what is called "the wet nurse's sleep." For a long period of time after delivery, they remain highly sensitive to even the smallest noises produced by the infant, while failing to register other loud noises as an arousal stimulus. The same experience is confirmed by wartime experiences of soldiers who were , able to sleep in the trenches through the thunderous roar of cannons but would become wide awake from the quietest ticking of the telegraph.

If the disturbances to falling asleep result from such external factors, there are several possibilities of help. The most immediate remedy, of course, is to reduce the noise, either through the use of double windows, heavily lined curtains, thick carpets, or by soundproofing the walls. Ear stoppers may also be helpful. Many people find them a problem, however, because they make one's own pulsebeat strongly audible. In addition, since they shut off acoustic contact with the world, they at the same time shut off sounds that one may wish to hear such as children crying or strange sounds in the house, and they make a conversation with one's spouse impossible.

Still another measure should be to try to diminish the emotionally negative content of a noise disturbance. This can be accomplished through the use of reason— i.e., by attempting to place the disturbance in its proper context. Relaxation can also help, and it can be learned. Autogenic training, for example, or some other auto-hypnotic technique can aid in learning to relax and in reducing emotional stress. These techniques will be discussed in greater detail further on. An advantage of such methods is that they can be used at

any time. They enable one to let sounds simply pass through one without responding with tension and resistance, and they teach one how to diminish the affective response to the disturbance.

Under some circumstances, this method can provide the only possibility of coexistence between snorer, who is otherwise an easy and even sleeper, and a non-snorer.

The reason for snoring is known. It evidently takes place mainly during the deep sleep phase—also possibly during REM sleep—through loss of basic muscle tension (muscle tone) in the musculature of the tongue and jaw. Snoring is most likely to occur if the sleeper is lying on his back, which causes the jaw to drop down and back and the tongue to slide back.

Sometimes the snorer even wakes himself up with his own snoring. In addition to the sound, which acts as an arousal stimulus, the snorer is awakened due to a lack of oxygen or shortness of breath. Snoring dependably wakes up the lightly sleeping partner and can even trigger a genuine wakefulness mechanism, since both persons become tense from the process of self-observation and expectation both of their own sleep and the sleep of the partner (mutually induced sleep disturbance). As a result, they are both impeded from falling asleep.

Still more grotesque (according to Finke and Schulte) is the process of "alternation"—i.e., partners alternate in disturbing each other's sleep. This occurs after the problem sleeper whose main obstacle to sleep was a snoring partner, has undergone successful therapy. Now cured of his difficulty in sleeping, he himself has started to snore and now keeps his partner awake.

Here, too, a problem that is mainly psychological creeps in. The snoring of another person is only felt to be disturbing if, apart from an allegedly abnormal sensitivity to noise and a low threshold of waking, the partner is in other respects felt to be "disburbing"—i.e., if tensions exist in other areas. The affect is the decisive factor in what is perceived as disturbing, so in many instances

separate bedrooms are necessary.

But even the snoring sleeper can do something to help the situation. He should in any case lie on his side before falling asleep and should constantly drum into his consciousness, "I am lying on my side, I am going to continue lying on my side." With steady practice and in the course of time, this works like a well-learned resolution. It is effective and carries over into sleep. We will deal with these principles later in the section on autogenic training.

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