Parasomnias are undesirable motor, verbal, or experiential phenomena that occur during the sleep period. They may be conveniently categorized as primary parasomnias (disorders of the sleep states per se), or secondary parasomnias (disorders of other organ systems that manifest themselves during sleep). The primary sleep parasomnias can be classified according to the sleep state of origin (rapid eye movement [REM]), non-rapid eye movement [NREM], or miscellaneous (those not respecting sleep state). Secondary sleep parasomnias can be further classified by the organ system involved.<sup>110 Mahowald M.W., Ettinger M.G. Things that go bump in the night—the parasomnias revisited J Clin Neurophysiol 1990 ;  7 : 119-143

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Integral to the understanding of parasomnias is the concept of state-dependent reorganization of the central nervous system (CNS). Until relatively recently, it was believed that sleep was a unitary phenomenon and simply represented the passive absence of wakefulness (W); a time of relative brain inactivity. In the 1930s, it was discovered that the brain is active during sleep. In 1953, it was discovered that sleep is actually a bimodal process—REM and NREM—indicating that, humans, as most mammals, spend their lives in three completely different states of being: W, REM sleep, and NREM sleep. Each of those states has its unique neuroanatomic, neurophysiologic, neurochemical, and neuropharmacologic correlates.<sup>10 Aserinski A., Kleitman N. Regularly occurring periods of eye motility, and concomitant phenomena during sleep Science 1953 ;  118 : 273-274

Cliquez ici pour aller à la section Références, 78 Jones B.E. Basic mechanisms of sleep-wake states Principles and Practice of Sleep Medicine Philadelphia: WB Saunders (1994).  145-162

Cliquez ici pour aller à la section Références, 193 Steriade M., Hobson J.A. Neuronal activity during the sleep-waking cycle Prog Neurobiol 1976 ;  6 : 155-376

Cliquez ici pour aller à la section Références, 206 Vertes R.P. Brainstem control of the events of REM sleep Prog Neurobiol 1984 ;  22 : 241-288  [cross-ref]

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There is compelling evidence that there is extensive reorganization of CNS activity during sleep. Almost all portions of the nervous system are active across all three states of being—but active in a different mode. Multiple state-determining variables are recruited to occur in concert, resulting in the declaration of a given state. Parasomnias are clinical phenomena, which, by-and-large, are related to the changes in brain organization across states, and are particularly apt to occur during the transition periods from one state to another.<sup>191 Spillane J.D., Nathan P.W., Kelly R.E. , et al. Painful legs and moving toes Brain 1971 ;  94 : 541-556

Cliquez ici pour aller à la section Références</sup> Given the large number of neural networks, neurotransmitters, and other state-determining substances that must be recruited synchronously, and given the frequent transitions among the three states of being, it is surprising that parasomnias do not occur more frequently than they do. The concept of state dissociation in animals and humans has been reviewed extensively.<sup>112 Mahowald M.W., Schenck C.H. Status dissociatus—a perspective on states of being Sleep 1991 ;  14 : 69-79

Cliquez ici pour aller à la section Références, 113 Mahowald M.W., Schenck C.H. Dissociated states of wakefulness and sleep Neurology 1992 ;  42 : 44-52

Cliquez ici pour aller à la section Références</sup> Figure 1 portrays a simplified conceptualization of the overlapping nature of the various parasomnias. Table 1 lists the various primary and secondary parasomnias.