A psychophysiological study of nightmares

Dreaming in posttraumatic stress disorder: A critical review of phenomenology, psychophysiology and treatment

This review summarizes the available knowledge on the phenomenology of posttraumatic dreams. Posttraumatic nightmares are reported by up to 70% of individuals suffering from posttraumatic stress disorder (PTSD). An extensive review of polysomnographic studies suggests that neither this high incidence nor the occurrence of posttraumatic nightmares throughout the sleep cycle can be explained by altered REM sleep parameters. The assumption that a reduction of dream recall may serve as a coping mechanism in PTSD patients is questionable. About 50% of posttraumatic dreams comprise exact replications of the traumatic events. Therefore dreams in PTSD do not have stereotypical content. Data characterizing non-replicative posttraumatic dreams and indicating a change in dream content over time must be considered preliminary. Occurrence of posttraumatic dreams is associated with psychopathological developments. Imagery Rehearsal Therapy has repeatedly been proven to be a valuable tool in treating patients suffering from posttraumatic dream disturbance. A deeper knowledge of posttraumatic dreams is essential for any theory of PTSD as well as for a better understanding of the overall function of dreaming.

Lucid dreaming treatment for nightmares: a pilot study

BACKGROUND

The goal of this pilot study was to evaluate the effects of the cognitive-restructuring technique 'lucid dreaming treatment' (LDT) on chronic nightmares. Becoming lucid (realizing that one is dreaming) during a nightmare allows one to alter the nightmare storyline during the nightmare itself.

METHODS

After having filled out a sleep and a posttraumatic stress disorder questionnaire, 23 nightmare sufferers were randomly divided into 3 groups; 8 participants received one 2-hour individual LDT session, 8 participants received one 2-hour group LDT session, and 7 participants were placed on the waiting list. LDT consisted of exposure, mastery, and lucidity exercises. Participants filled out the same questionnaires 12 weeks after the intervention (follow-up).

RESULTS

At follow-up the nightmare frequency of both treatment groups had decreased. There were no significant changes in sleep quality and posttraumatic stress disorder symptom severity. Lucidity was not necessary for a reduction in nightmare frequency.

CONCLUSIONS

LDT seems effective in reducing nightmare frequency, although the primary therapeutic component (i.e. exposure, mastery, or lucidity) remains unclear.

Evaluating the awakening criterion in the definition of nightmares: how certain are people in judging whether a nightmare woke them up?

There is debate about whether to include in the definition of nightmares a criterion that the imagery or emotions of the nightmare caused the person to wake up. This study investigates whether people believe that they can judge this cause of awakening. 42 participants recorded for 14 nights whether they had a dream, and decided for each dream whether it had or had not woken them. They then rated on a 5-point scale (where 1 = very certain and 5 = very uncertain) how certain they were in their decision of whether or not the dream woke them. Participants' mean certainty was high for decisions that the dream woke them (mean certainty = 1.60), and for very unpleasant dreams this mean certainty that the dream woke them was very high (mean certainty = 1.27). Dreams judged to have caused awakening were found to be more unpleasant than dreams judged not to have caused awakening. Although the inclusion of the awakening criterion did not increase the association of nightmare frequency with anxiety, there may be other advantages in the use of the awakening criterion.

Initial validation of the SLEEP-50 questionnaire

Initial psychometric properties of the SLEEP-50 questionnaire, designed to detect sleep disorders as listed in the Diagnostic and Statistical Manual of Mental Disorders (4th ed., Text Revision), were examined. The sample consisted of 377 college students, 246 sleep patients, 32 nightmare sufferers, and 44 healthy volunteers. The internal consistency was high (Cronbach's alpha = .85); test-retest correlations fell between .65 and .89. Principal component analysis with a direct oblimin rotation revealed a factor structure that closely matched the designed structure. Sensitivity and specificity scores were promising for all sleep disorders; the agreement between all clinical diagnoses and SLEEP-50-classifications was substantial (kappa = .77). These initial findings indicate that the SLEEP-50 seems able to detect a variety of sleep disorders. The SLEEP-50 can aid in screening for common sleep disorders in the general population.

Nightmares: from anxiety symptom to sleep disorder

The DSM-IV-TR definition of nightmares-extremely frightening dreams from which the person wakes up directly-is unnecessarily narrow. Other emotions (anger, grief) have also been reported in nightmares, and direct awakening from a bad dream seems to be unrelated to increased distress. In addition, assessment of nightmares is problematic. Polysomnographic recordings have an ameliorating effect on nightmare frequency, retrospective measurements tend to underestimate nightmare frequency, and persons with frequent nightmares may feel reluctant to fill out (daily) prospective measurements. For studying nightmares, it is necessary to distinguish idiopathic nightmares from posttraumatic nightmares, which are part of a posttraumatic stress reaction or disorder that may result from experiencing a traumatic event. Both types of nightmares have been associated with an elevated level of periodic limb movements, although only posttraumatic nightmares seem to be related to more and longer nocturnal awakenings. Nightmares have also been repeatedly associated with the general level of psychopathology, or the so-called personality factor neuroticism. Nightmare distress, the impact on daily functioning caused by nightmares, may function as a mediating variable. Several studies in the last decades have shown that nightmares can be treated with several cognitive-behavioral techniques. The cognitive-restructuring technique imagery rehearsal therapy is the treatment of choice for nightmares, although a randomized controlled trial with an attention control-group has not yet been carried out. Nightmares are more than a symptom of a larger (anxiety) syndrome and need to be viewed from a sleep medicine perspective: nightmares are a highly prevalent and separate sleep disorder that can and should receive specific treatment.

Impact of imagery rehearsal treatment on distressing dreams, psychological distress, and sleep parameters in nightmare patients

We investigated the impact of imagery rehearsal treatment (IRT) on nightmare frequency, psychological distress, and sleep quality using polysomnography (PSG). 12 chronic nightmare patients completed prospective dream logs, measures of psychological distress, and underwent PSG prior to and 8.5 weeks following a single IRT session. Post-treatment, significant reductions were observed in retrospective nightmare frequency (d = 1.06, p = .007), prospective bad dream frequency (d = 0.53, p = .03), and anxiety scores (d = 1.01, p = .004). Minimal sleep alterations were found post-IRT, and varied as a function of nightmare etiology. The results independently replicate the efficacy of IRT for alleviating disturbing dreams and psychological distress. Sleep improvement may occur later in the recovery process.

Sleep pathophysiology in posttraumatic stress disorder and idiopathic nightmare sufferers

BACKGROUND

Nightmares are common in posttraumatic stress disorder (PTSD), but they also frequently occur in idiopathic form. Findings associated with sleep disturbances in these two groups have been inconsistent, and sparse for idiopathic nightmares. The aim of the present study was to investigate whether sleep anomalies in PTSD sufferers with frequent nightmares (P-NM) differ from those observed in non-PTSD, idiopathic nightmare (I-NM) sufferers and healthy individuals.

METHODS

Sleep measures were obtained from nine P-NM sufferers, 11 I-NM sufferers, and 13 healthy control subjects. All participants slept in the laboratory for two consecutive nights where electroencephalogram, electro-oculogram, chin and leg electromyogram, electrocardiogram, and respiration were recorded continuously.

RESULTS

Posttraumatic nightmare sufferers had significantly more nocturnal awakenings than did I-NM sufferers and control subjects. Elevated indices of periodic leg movements (PLMs) during rapid eye movement (REM) and non-REM sleep characterized both P-NM and I-NM sufferers.

CONCLUSIONS

Posttraumatic nightmare sufferers exhibit more nocturnal awakenings than do I-NM sufferers and control subjects, which supports the hypothesis of hyperarousal in sleep in PTSD sufferers; however, elevated PLM indices in both P-NM and I-NM sufferers suggest that PLMs may not be a marker of hyperarousal in sleep of PTSD sufferers. Rather, PLMs may be a correlate of processes contributing to intense negative dreaming.

Laboratory sleep correlates of nightmare complaint in PTSD inpatients

BACKGROUND

Nightmares are rare in the sleep laboratory, even in patients with posttraumatic stress disorder for whom nightmare complaints are diagnostic. Nevertheless, it is possible that laboratory conditions do not preclude the observation of telltales-nightmare-related modifications of tonic sleep-given sufficiently large samples.

METHODS

Sixty-three unmedicated, nonapneic Vietnam combat veterans undergoing inpatient treatment for posttraumatic stress disorder underwent polysomnographic testing and assessment of nightmare complaint.

RESULTS

Trauma-related nightmare complaint, but not non-trauma-related complaint, was associated with increased wake-after-sleep-onset in the sleep laboratory. No relationships between nightmare complaint and rapid eye movement sleep architecture were observed.

CONCLUSIONS

Increased wake-after-sleep-onset was specifically associated with trauma-related nightmare complaint, confirming data from other quarters suggesting they are both phenomenologically and functionally distinct from normal dreaming.

Sleep and dreams in Vietnam PTSD and depression

The present study compares the sleep and dreams of three groups of subjects: 1) Vietnam veterans with posttraumatic stress disorder (PTSD) and major depression, 2) veterans with depression alone, and 3) veterans with neither PTSD nor depression (i.e., normal controls). Sleep recordings indicate only one significant difference between the PTSD/depressed and depressed alone groups: sleep latency was prolonged in the depressed alone patients compared with the other two groups. The two patient groups differed from controls in the manner already reported for depressed patients (decreased REM latency, increased REM density, reduced total sleep time, reduced sleep efficiency), with some of the differences significant only at the trend level. Dreams were obtained from REM awakenings. Dream recall rate and report length did not differ between groups. Mean anxiety level in dreams was less than 1 (mild) for all three groups, with major depression patients scoring significantly higher than controls. Dreams of PTSD/depressed patients were significantly less likely to be set in the present than dreams of the other two groups.

Psychophysiological aspects of nightmares, night terrors, and sleepwalking

Monitoring sleep through electroencephalography and electroculography has identified the different sleep stages in which nightmares, night terrors, and sleepwalking occur. Questionnaire surveys have supplemented the findings of case studies of these sleep disorders. Neurotransmitters operative during these sleep disorders have enlarged the knowledge of the psychophysiological dimensions especially of nightmares.

Auditory evoked potentials in narcolepsy and sleep terrors

Dysfunction of brainstem reticular activating centers has been suggested in some sleep disorders, including narcolepsy and sleep terrors. Previous studies have suggested normal brainstem auditory evoked potentials (BAEPs) in narcolepsy and enhancement of long-latency auditory event-related potentials (ERPs) in sleep deprivation and conditions of pathological somnolence. Sleep terrors have not to date been studied neurophysiologically. We recorded early latency BAEPs and long-latency auditory ERPs in 8 patients with narcolepsy and 5 individuals with sleep terrors, and compared them to 10 normal controls. Narcolepsy patients and controls did not differ significantly in absolute or interpeak latency of BAEPs. Sleep terror patients had significant prolongation relative to controls of III-V and I-V interpeak latencies. The N1, N2, and P3 AEP components were prolonged in latency in narcoleptic patients as compared to controls, while sleep terror patients did not differ from controls. No significant differences in amplitude were found. These findings suggest that a disturbance of integration of brainstem centers subserving wakefulness and sleep may play a role in the disordered arousal of sleep terrors, but suggest no specific abnormality in brainstem function in narcolepsy. The AEP changes in narcolepsy may be a manifestation of pathological sleepiness.

Automatism, medicine and the law

The law on automatism is undergoing change. For some time there has been a conflict between the medical and the legal views. The medical profession believes that the present division between sane and insane automatism makes little medical sense. Insane automatism is due to an internal factor, that is, a disease of the brain, while sane automatism is due to an external factor, such as a blow on the head or an injection of a drug. This leads to the situation where, for example, the hypoglycaemia resulting from injected insulin would be sane automatism, while hypoglycaemia while results from an islet tumour would be insane automatism. This would not matter if the consequences were the same. However, sane automatism leads to an acquittal, whereas insane automatism leads to committal to a secure mental hospital. This article traces the development of the concept of automatism in the 1950s to the present time, and looks at the anomalies in the law as it now stands. It considers the medical conditions of, and the law relating to, epilepsy, alcohol and drug automatism, hypoglycaemic automatisms, transient global amnesia, and hysterical automatisms. Sleep automatisms, and offences committed during a somnambulistic automatism, are also discussed in detail. The article also examines the need of the Courts to be provided with expert evidence and the role that the qualified medical practitioner should take. It clarifies the various points which medical practitioners should consider when assessing whether a defence of automatism is justified on medical grounds, and in seeking to establish such a defence. The present law is unsatisfactory, as it does not allow any discretion in sentencing on the part of the judge once a verdict of not guilty by virtue of insane automatism has been passed. The judge must sentence the defendant to detention in a secure mental hospital. This would certainly be satisfactory where violent crimes have been committed. However, it is inappropriate in many cases where non-violent confusional crimes, such as petty larceny, have been committed. Suggestions are made for desirable changes in the law.

Relations among nightmare frequency and ego strength, death anxiety, and sex of college students

The present study was designed to investigate empirically the relationship between self-reports of nightmare frequency and ego strength and death anxiety in both men and women. In addition, the interrelations among these variables were assessed. 20 undergraduates with high frequencies of nightmares and 20 with low frequencies (10 men and 10 women per group) were administered the Barron Ego Strength Scale and a death anxiety scale. Significant differences were found between nightmare groups on the Barron scale for men and women but none on the death anxiety scale either by nightmare frequency or sex. A significant negative correlation of -.47 between death anxiety and ego strength was found for women and in one high frequency group. Women with high frequencies of nightmares showed the highest correlation, -.83. These data suggest that nightmare frequency may be a mediating factor in the relationship between ego strength, death anxiety, and sex of subject.

Night terrors and sudden unexplained nocturnal death

A high incidence of sudden unexplained nocturnal deaths has been reported among young Asian males. These deaths are known as Pokkuri in Japan, Bangungut in the Philippines and Sudden Unexplained Nocturnal Death in the United States. Post mortem analysis has demonstrated cardiac conduction defects in many of the victims. Careful review of the terminal events surrounding these deaths suggests that the victims suffered from night terrors. Night terrors are a sleep disorder characterized by vocalization, motor activity, a nonarousable state, and severe autonomic discharge. The proposed recognition of both night terrors and cardiac anomalies in these patients offers a pathophysiologic mechanism for their sudden death.

Repetitive visual images in severe war head injuries

Out of 20 young inpatients who suffered missile head injuries, two (10%) presented repetitive visual images (RVI). The RVI appeared during wakefulness when relaxed with closed eyes and also at sleep stage I, II and REM, at sleep onset and at sleep end. When the two patients were compared neurologically and psychologically with the other eighteen, the coexistence of combat stress syndrome, diffuse brain lesions, right non-dominant associative area damage and homonymous hemianopia characterised the two RVI patients. RVI do not appear in the absence of the combat stress syndrome even in the presence of the other 3 factors. The sleep may be secondarily contaminated by wakefulness RVI. The presence of disturbed REM temporal distribution and short REM latency indicate the depressive state of these patients. It is hypothesised that a similar brain activity in wakefulness and REM sleep explain the wake dreaming or wakefulness RVI of those patients.

Insomnia and other sleep disorders

In treating the symptomatology of patients who are chronically ill, it is likely that the physician will encounter a significant number of patients who have sleep disorders. This article has described an approach for the assessment, differential diagnosis, and clinical management of the most prevalent sleep disorders, which are often chronic in nature and have significant psychosocial or medical consequences for the patient and his or her family. We have emphasized the importance for the physician to complement his general medical and diagnostic skills by taking a careful sleep history from the patient (and, in some instances from the bed partner or caretakers). There is no justification for the physician to routinely request costly sleep laboratory hypnopolygraphic evaluations to screen patients with sleep disorders. However, in those instances where the sleep history is highly suggestive of sleep apnea, a sleep laboratory evaluation is indicated. By incorporating the use of the sleep history in the general evaluation of patients with sleep disorders, the physician is better able to develop rational pharmacologic and non-pharmacologic approaches to managing these patients, including the judicious use of medication as an adjunctive treatment.

Human consciousness and sleep/waking rhythms: a review and some neuropsychological considerations

The relevance of sleep/waking rhythms to issues of human consciousness is reviewed from data in the literature and from personal studies. Consciousness is often considered to be markedly attenuated or absent in sleep. There is, however, much evidence for a rich subjective experience during sleep, much of which is not recalled later. This implies that William James' "stream of consciousness' persists continuously throughout sleep as well as wakefulness, but that problems of memory recall interfere with its being reported as such. Sleeping subjects show selective awareness of external stimuli, with significant stimuli generally leading to awakening and relatively nonsignificant stimuli, at least at times, being incorporated into the ongoing mental activity of REM or NREM sleep. Mentation throughout sleep is characterized by a high degree of autonomy and little willful control. Creative insight and problem solving of a very high order may occur in sleep and involve either dreaming or thought-like mentation. Parameters of waking consciousness show possibly sleep-related rhythmic fluctuations at both circadian (24 hr sleep/waking) and ultradian (90-120) min, NREM/REM sleep) rates. Moreover, waking consciousness is markedly influenced by the quality of temporal stability of preceding sleep. A substantial number of so-called "altered states of consciousness" is found to involve primarily or exclusively dysfunction of sleep/waking mechanisms. Cerebral lesions can produce selective impairment of aspects of sleep mentation. It is concluded that further analysis of subjective awareness in sleep or in partial sleep states is very relevant and indeed vital to a more comprehensive understanding of human consciousness.

Evaluation of flurazepam and placebo on sleep disorders in childhood

The clinically observed results in 40 patients, from 1 to 15 years old, presenting sleep disturbances, in a comparative and statistically approached study of flurazepam 15mg daily against placebo, are reported. Placebo was administered, followed by the drug, during 14 days each. The chief complaints were sleepwalking, sleep-talking, sleep terror, sleep-related bruxism, sleep-related headbanging, insomnia and excessive movements during sleep. A significant effect of flurazepam on sleepwalking, sleep-talking, bruxism, sleep terror and excessive movement during sleep, was observed. The insomniac headbanging patients were not enough for statistical analysis. Flurazepam side effects were excessive drowsiness during daytime in 3 cases; irritability, 3 cases; nausea and vomiting, 2 cases, and were not correlated with age. Placebo side effects were similar, except for nausea and vomiting which were not observed. It was necessary to discontinue flurazepam in 2 cases, because of excessive drowsiness during daytime, which did not improve when reducing the dose.

[Sleep in children with episodic sleep phenomena: a comparison with the normal child]

(1) The sleep pattern of 23 children, aged 5-12 years, with episodic nocturnal phenomena (night-terrors, somnambulism, rhythmic movements) was recorded during two successive nights. It was compared with that of a group of 21 normal children of the same age. (2) In the pathological group, slow wave sleep (SLP, stages 3 and 4) was significantly shortened during the 2 nights. This deficit mainly involved the first 3h of sleep. (3) As for the slow wave sleep, REM sleep (SP) modifications prevailed during the first hours of sleep. The first REM period was delayed and preceded by more numerous and atypical partial REM periods. The duration of the first REM period increased faster as a function of its latency than in the normal child. (4) In contrast with this difficulty for REM sleep to occur during the first part of the night, the subsequent REM sleep pattern was similar in the 2 groups (total REM sleep duration, mean REM period duration, mean REM cycle duration). For equal latencies, REM periods had similar duration. Finally, the total REM sleep amount was a linear function of the total sleep time, with more or less identical coefficients for the two groups. (5) The part played by these modifications during the first hours of sleep in the occurrence of night terrors and somnambulism is discussed.