The Realms of Disordered Sleep
Three very general but often overlapping symptom clusters lead people to seek help for their difficulties with sleeping. Most basically, these are too little sleep, too much sleepiness, and problematic behaviors during sleep. The complaint of not feeling able to sleep—insomnia—is the focus of this book. Insomnia is the most common sleep problem but not necessarily the most likely to prompt a visit with a health care professional. A diversity of processes contributing to the insomnia complaint is elaborated in the next four chapters. These include various psychological and physiological factors. The expectation of normal sleep includes the assumption that one should be fully alert and free of excessive sleepiness during the waking hours. However, excessive sleepiness when one desires to be awake is a common difficulty and sometimes a major clinical problem. People with severe symptoms often do seek treatment, since sleepiness can interfere with daytime functioning. Excessive sleepiness most frequently is the result of sleep deprivation—acute or chronic.
People sometimes are unaware that they do not allot sufficient time for adequate sleep, and they assume that some other problem must be accounting for their sleepiness and fatigue. However, certain sleep disorders certainly can cause daytime sleepiness that can range from mild to severe and that even can be life threatening in the context of driving or other situations of responsibility. With sleep-disordered breathing, there may be a normal amount of sleep; however, the quality of the sleep may be very poor. This may be indicated by a high percentage of NREM stage 1 sleep as well as reductions in SWS and REM sleep. In severe cases, the problem can be complicated by significant recurrent decreases in oxygen saturation levels. Some individuals exhibit frequent involuntary body movement during sleep, as with periodic limb movement disorder. These brief muscle contractions may be associated with arousals that decrease the quality of sleep and, in severe cases, can contribute to daytime sleepiness. Narcolepsy, a genetically influenced disorder with malfunction in the hypocretin (orexin) system, causes persistent daytime sleepiness as well as other symptoms reflecting abnormalities in REM sleep regulation. A variety of other pathological brain processes (e.g., traumatic, neoplastic, metabolic, and infectious) also may cause excessive daytime sleepiness. Finally, some medications and other substances can cause excessive sleepiness.
The third broad category of sleep disorders are the parasomnias, which are behaviors and abnormalities that emanate from sleep but are not primary problems of too much or too little sleep. However, patients with parasomnias may offer a chief complaint of insomnia when their sleep-related events cause annoying awakenings, or they may complain of excessive sleepiness when the parasomnia undermines their ability to achieve a sufficient amount of sleep. Some people with parasomnias are unaware of their sleep-related abnormalities and know of them only through other informants. The primary parasomnias include such phenomena as sleepwalking, sleep terrors, confusional arousals, nightmares, and REM behavior disorder. Being asleep also may increase the risk in vulnerable individuals for seizure activity, asthma episodes, arrhythmias, and panic attacks. Bruxism and enuresis may occur during sleep. The current understandings of sleep architecture described above are very helpful in differentiating the parasomnias, as several are associated with particular sleep stages. For instance, the dream-related anxiety of nightmares emerges from REM sleep. Slow-wave sleep is associated with confused behaviors occurring from sleep, especially with sleep terrors and confusional arousals. The common denominator in this wide assortment of sleep-related complaints is that the experience deviates from the expectation of a normal sleep-wake cycle. People expect the ability to fall asleep quickly and remain asleep uninterrupted long enough (i.e., about eight hours) to feel fully alert during their waking hours. Wakefulness and sleep-disturbing behaviors should not intrude on sleep, and sleepiness should not intrude on wakefulness. Clearly, there are many reasons why this ideal fails to be achieved.
Source: David N. Neubauer, “Understanding Sleeplessness: Perspectives on Insomnia,” The Johns Hopkins University Press, Baltimore 2003
Republished by Health Care Programs