the body assert themselves, while the psychological needs become "involuntary." This does not mean that sleep is solely a physical function. To the contrary, dreaming stages of sleep, which may be experienced in psychological terms, are actually "used" by the physical organism to reconstitute itself. It is as if the psychological experience of the dream serves highly patterned physiological purposes, and vice versa.
Whatever the dream theorists may come up with regarding the psychophysiological function of sleep, the importance of sleep to the organism is generally agreed upon. Further, the negative effects of sleep deprivation, from whatever source, have been found in the research (just as in the experience of individuals) to be manifest on both psychological and physiological levels of human functioning.
If it follows from the benefits of sleeping and dreaming that the absence of them may be detrimental to the organism, it might seem that the definition of insomnia as the inability to fall asleep (Oldham, 1995) would be quite straightforward and unambiguous. It would seem merely a logical fact that an absence of the restorative properties of rest would be unhealthful. But that is about all the experts can agree upon. Controversy or at least difference of opinion surrounds virtually every aspect of insomnia research, beginning with the scope and precision of the definition of the condition and continuing through a range of medical opinion about its causes, effects, and treatment.
Definition is the first order of business. One comprehensive view of the sleep disorder defines it in terms of both psychology and physiology, as:
an experience of inadequate or poor-quality sleep characterized by one or more of the following problems: difficulty falling asleep, difficulty maintaining sleep, waking up too early in the morning and sleep that is not refreshing. Insomnia also involves daytime consequences such as fatigue, lack of ener...