Articles

WHAT IS SLEEP: DEVIATIONS FROM THE SLEEP NORM

Various phases of this normal sleep pattern can be affected by sleep disturbances. For example, the time that elapses before the beginning of the first deep sleep phase can be lengthened, and the first REM phase can be incomplete (unsuccessful REM sleep). And instead of the normal cyclic leveling-off into deep sleep, an interval of complete wakefulness can occur, thereby shortening the total sleep time and having a subjective effect on the feeling of restoration in the morning. In addition, the quantitative relation between synchronic and asynchronic REM sleep seems to be important. And, finally, the entire cyclic succession of the separate phases can be jumbled up, which occurs in severe mental illness.

Brain wave tracings documenting experiments conducted in the sleep laboratory have revealed still other findings of importance to persons with sleep problems. One is the evident difficulty in judging one's own sleep. Many test subjects who indicated that they had only thought about something but had not slept had in reality dreamed. They did not perceive the duration of light sleep periods and gave false estimates of the duration of intervals of wakefulness. This shows that disturbances of this periodic event are subjectively overrated and are experienced far more strongly than indicated by objective findings. Hence the impression of not having slept the whole night is often demonstrably false. But since the morning feeling of restoration is largely based on an awareness of the amount of sleep, it is understandable why the feeling of difficulty in sleeping can be so strong despite an objectively sufficient amount of sleep. The

reason is that it is almost impossible to judge one's own sleep without special equipment. The idea that one has usually slept more than one thought should therefore provide some comfort, because the body in any case gets the minimal quantity of sleep needed.

The sleep periods—i.e., the two-hour rhythmic course of the various sleep phases—account for why it is so difficult to fall asleep again if the first deep sleep is interrupted. A new high point of fatigue simply does not occur until two hours later, and there is really not much sense in trying to force sleep against this biological rhythm, because the body just will not cooperate. In such an instance, it is better to wait for a new period of fatigue, perhaps to fill the interval by reading, and to give in and wait for the organism's next demand for sleep, which will occur with the next drop in the synchronic sleep curve.

The fact that other bodily functions also change in response to the particular stage of sleep has already been mentioned. These include in particular the heart rate, blood pressure, frequency and depth of breathing, and therefore the supply of oxygen to the blood, dilation of the pupils, perspiration, and excitation of the sex organs. We will later see that this linkage of sleep periods to the autonomic nervous system also often gives us the opportunity of positively influencing sleep in the regulation of these mechanisms. These events also support the contemporary definition of sleep as an active accomplishment of the organism resulting in extensive changes in bodily processes.

*6\340\2*