Curious paralytic phenomena, referred to as preand postdormital paralyses, may occur in the transition from the sleeping to the waking state. Sometimes in the morning and less frequently when falling asleep, otherwise healthy persons—though awake, conscious, and fully oriented—are seemingly unable to activate their muscles. Respiratory and diaphragmatic function and eye movements are usually unaffected, although a few patients have reported a sensation of being unable to breathe. They lie as though still asleep, with eyes closed, and may become quite frightened while engaged in a struggle for movement. They have the impression that if they could move one muscle, the paralysis would be dispelled instantly, and they would regain full power. It has been stated that the slightest stimulus, such as the touch of a hand or calling the patient’s name, will abolish the paralysis. Sleep deprivation is a common precipitant to the syndrome.
Such attacks are also observed in patients with narcolepsy (discussed later in this chapter) and with the hypersomnia of the pickwickian syndrome and other forms of sleep apnea. Some cases are familial.
The weakness or paralysis is thought to be a dissociated form of the atonia of REM sleep. Usually, the attacks are brief (minutes or less); if they occur in isolation and only on rare occasions, they are of no special significance. If frequent, as in narcolepsy, they can be prevented by the use of tricyclic antidepressants, particularly clomipramine, which has serotonergic activity.
The night terror (pavor nocturnus) is mainly a problem of childhood. It usually occurs soon after falling asleep, during stage 3 or 4 sleep and therefore is not aligned with nightmares. The child awakens abruptly in a state of intense fright, screaming or moaning, with marked tachycardia (150 to 170 beats/min) and deep, rapid respirations. Children with night terrors are often sleepwalkers as well, and both kinds of attack may occur simultaneously. The entire episode lasts several minutes and in the morning the child recalls nothing of it or only a vague unpleasant dream. It has been suggested that night terrors and somnambulism represent impaired or partial arousal from deep sleep, as EEGs taken during such episodes show a waking type of mixed frequency and alpha pattern. Children with night terrors and somnambulism do not show an increased incidence of psychologic abnormalities and tend to outgrow these disorders. The persistence of such problems into adult life, however, has, in a small number of cases, been associated with psychopathology (Kales et al). It has been found that diazepam, which reduces the duration of the deep stages of sleep, will prevent night terrors. Selective serotonin reuptake inhibitors have also been used successfully, especially when night terrors are associated with sleepwalking. Frequent night terrors have reportedly been eliminated by having parents awaken the child for several successive nights, just prior to the usual time of the attack or at the first sign of restlessness and autonomic arousal (Lask).