Idiopathic Nightmares and Dream Disturbances Associated with Sleep–Wake Transitions 1107
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Idiopathic Nightmares and Dream Chapter Disturbances Associated with Sleep–Wake Transitions Tore Nielsen and Antonio Zadra 97 Abstract described, with much support for the effectiveness of short- term cognitive and behavior interventions such as systematic Nightmares and other common disturbances of dreaming desensitization and imagery rehearsal. Several related dream involve a perturbation of emotional expression during sleep. disturbances occur at the transitions into or out of sleep and Nightmares, the most prevalent dream disturbance, are now involve dysphoric emotions ranging from malaise to fear to recognized as comprising several dysphoric emotions, includ- frank terror. These disturbances include sleep starts, terrify- ing especially fear, although some argue that existential (or ing hypnagogic hallucinations, sleep paralysis, somniloquy grief) dreams should be considered a separate entity. A with dream content, false awakenings, and disturbed lucid genetic basis for nightmares has been demonstrated and their dreaming. The distinctive nature of these disturbances may pathophysiology involves a surprising underactivation of the be mediated by immediately preceding waking state processes sympathetic nervous system in many instances. Personality (e.g., consciousness, sensory vividness) that intrude upon or factors, such as nightmare chronicity and distress and coping carry over into dreaming. styles are mediating determinants of their clinical severity, as are drug and alcohol use. Many treatments have been Because most common dreaming disturbances (Table pathologic in some sense.15 However, the widespread belief 97-1) involve a perturbation of emotional expression that dreaming can serve an emotionally adaptive function during sleep, their study may help clarify the role of (see Chapter 54) also suggests that some dream distur- emotion in dream formation, dream function, and sleep bances are adaptive reactions to more basic pathophysio- mechanisms more generally. Physiologic evidence for logic factors rather than pathological per se.16 emotional activity during rapid eye movement (REM) sleep is substantial. Autonomic system variability increases IDIOPATHIC NIGHTMARES markedly in conjunction with central phasic activation,1 as seen especially in measures of cardiac function,2,3 respira- Historical Aspects tion,4 and skin and muscle sympathetic nerve activity.5 The Diagnostic and Statistical Manual of Mental Disorders, Brain imaging, too, demonstrates increased metabolic 4th edition (DSM-IV)17 criteria for nightmare disorder activity in limbic and paralimbic regions during REM (Table 97-2) have not changed substantially since the dis- sleep6 activity similar to that seen during strong emotion order was previously described as “dream anxiety disorder” in the waking state.7 These dramatic autonomic fluctua- in the DSM-III-R and “dream anxiety attack” in the DSM- tions globally parallel dreamed emotional activity, which III. The International Classification of Sleep Disorders, 2nd is detectable throughout most dreaming when appropriate edition (ICSD-II) criteria for nightmares (see Table 97-2) probes are employed.8 Some studies indicate that most have changed only slightly since the first edition (ICSD). dreamed emotion is negative,9 primarily fearful,8 and may Some new research on the phenomenology of nightmares conform to a surgelike structure within REM episodes.10 has prompted a redefinition of the term nightmare in the Many theorists interpret the various forms of phasic activ- more recent ICSD-II. ity occurring during sleep as indicating dream-related The widely accepted definition of a nightmare has long affective activity.11,12 been “a frightening dream that awakens the sleeper,” but Waking state emotional and cognitive reactions are also researchers have come to reevaluate these defining fea- implicated in dream disturbances. For the most common tures. Some18 argue that the “awakening” criterion should disturbances, such as nightmares, dreamed emotions indeed designate nightmares but that disturbing dreams become unbearably intense, provoking an awakening that that do not awaken (“bad dreams”) should nevertheless be can lead to further distress, depressed mood, avoidance and considered clinically significant. Whether or not the coping behavior, and often even impairment of subsequent person awakens presumably reflects a dream’s emotional sleep. Perturbation of dream-related emotion can thus lead severity, but it is not the only index of severity. First, to a cycle of sleep disruption and avoidance, insomnia,13 among patients with various psychosomatic disorders, even and psychological distress that often leads the person to the most macabre and threatening dreams do not neces- seek out professional help.14 sarily produce awakenings.19 Second, less than one fourth However, causal relationships among emotion, dream- of patients with chronic nightmares report “always” awak- ing, and other associated symptoms are not well under- ening from their nightmares, and these awakenings do not stood. The emotional disruption inherent in nightmare correlate with either nightmare intensity or psychological disorder may be limited to sleep-related processes, in distress.13 Third, among subjects with both nightmares and L which case the dreaming process itself might be considered bad dreams, approximately 45% of bad dreams are rated 1106 Kryger_6453_Ch 97_main.indd 1106 8/27/2010 6:58:06 PM CHAPTER 97 • Idiopathic Nightmares and Dream Disturbances Associated with Sleep–Wake Transitions 1107 Table 97-1 Sleep Disorders in which Disturbed Dreaming is Common SlEEP DISORDER CODE* STAGE PREvAlENCE ESSENTIAl FEATuRES Nightmare disorder 307.47-0 REM, 2 Preschoolers: 5%-30% Frightening dreams; awakening Young adults: 2%-5% Terrifying hypnagogic 307.47-4 Sleep onset Rare Terrifying dreams similar to those hallucinations Narcolepsy: 4%-8% from sleep Sleep starts 307.47-2 Sleep onset Lifetime: 60%-70% Sudden brief jerks associated Extreme form: rare with sensory flash, hypnagogic dream, or feeling of falling Sleep paralysis 780.56-2 Sleep onset Isolated, normal persons: Paralysis of voluntary muscles; or offset 1/lifetime in 40%-50% acute anxiety (with or without Familial: rare dreams) is common *American Sleep Disorders Association: International classification of sleep disorders, revised: diagnostic and coding manual. Westchester, Ill: American Sleep Disorders Association; 1997. Table 97-2 Clinical Criteria for Nightmare Disorder DSM-Iv DIAGNOSTIC CRITERIA FOR ICSD-II DIAGNOSTIC CRITERIA FOR CRITERIA NIGHTMARE DISORDER (307.47) NIGHTMARES (307.47-0) Nature of recalled dream Repeated awakenings from the major sleep Recurrent episodes of awakenings from period or naps with detailed recall of extended sleep with recall of intensely disturbing and extremely frightening dreams, usually dream mentation, usually involving fear involving threats to survival, security, or or anxiety but also anger, sadness, self-esteem. disgust, and other dysphoric emotions. Recall of sleep mentation is immediate and clear. Nature of awakening On awakening from the frightening dreams, the Alertness is full immediately on awakening, person rapidly becomes oriented and alert (in with little confusion or disorientation. contrast to the confusion and disorientation seen in sleep terror disorder and some forms of epilepsy). Nature of distress The dream experience, or the sleep disturbance Associated features include at least one of resulting from the awakening, causes clinically the following: significant distress or impairment in social, • Return to sleep after the episodes is occupational, or other important areas of typically delayed and not rapid. function. Timing The awakenings generally occur during the second half of the sleep period. • The episodes typically occur in the latter half of the habitual sleep period. Differential diagnosis The nightmares do not occur exclusively during Nightmares are distinguished from several the course of another mental disorder (e.g., a other disorders in a Differential Diagnosis delirium, posttraumatic stress disorder) and are section: seizure disorder, arousal not due to the direct physiologic effects of a disorders (sleep terrors, confusional substance (e.g., a drug of abuse, a medication) arousal), REM sleep behavior disorder, or a general medical condition. isolated sleep paralysis, nocturnal panic, posttraumatic stress disorder, acute stress disorder. on a level of emotional intensity that is equal to or exceeds some argue18 that nightmares can involve any unpleasant that of the average nightmare.20 In short, whereas disturb- emotion. However, distressing dreams related to bereave- ing dreams often can awaken a sleeper, awakenings are not ment are considered by some as constituting a distinct the sole or even the best index of the severity of the nosologic entity known as existential dreams.21 disorder. Similarly, researchers have come to define nightmares Prevalence and Frequency more inclusively with respect to their emotional tone. This Lifetime prevalence for a nightmare experience in the is reflected in the modified ICSD-II definition of night- general population is unknown but may well approach mares as “disturbing mental experiences” rather than as 100%. If we consider only dreams of attack and the pursuit “frightening dreams” as in the ICSD. Although fear theme, which are the most common nightmare themes, the remains the most commonly reported nightmare emotion,20 lifetime prevalence varies from 67%22 to 90%.23