No Evidence of Sleep Disturbance in Post-Traumatic Stress Disorder: A Polysomnographic Study in Injured Victims of Traffic Accidents

Article excerpt

Abstract: Background: Disturbed sleep is a common complaint among patients with PTSD. This complaint can be found in both the reexperiencing and hyperarousal symptom clusters in the DSM-IV. However, laboratory studies of sleep in PTSD have provided inconsistent evidence of objective sleep disturbances. Shortened REM latency, reduced sleep efficiency, restless sleep and increased prevalence of sleep apnea have been reported, but were not confirmed by all. A major shortcoming of most previous studies is the fact that they were done retrospectively in patients with chronic PTSD, often complicated by psychiatric comorbidity and drug abuse. Thus, little is known about the development of sleep disturbances in recently traumatized subjects. Method: Eight injured victims of traffic accidents with PTSD and 6 injured victims without PTSD participated in a 3-night polysomnographic study one year after the accident. Results: No significant differences between PTSD and non-PTSD patients were noted on any of the PSG measures. In addition, the two groups did not differ significantly from each other with respect to awakening thresholds during REM sleep. Conclusion: Considering that the present sample was free of active psychiatric comorbidity at the time of trauma and free of hypnotic medications, these results strengthen previous PSG studies suggesting that altered sleep perception, rather than sleep_ disturbance per se, may be the key problem in PTSD. More research is needed in order to examine whether this problem is specific to sleep or generalizes to other domains as well.

Impaired sleep is a common complaint among PTSD sufferers. This complaint can be found in both the reexperiencing and hyperarousal symptom clusters in the DSM-- IV (1). In the former domain, symptoms related to sleep are characterized by intrusion of traumatic memories or other threatening themes into dreams. Insomnia and nightmares, an extreme manifestation of this problem, have even been referred to as the "hallmark" of PTSD (2). Hyperarousal symptoms related to sleep include difficulties regulating (i.e., initiating and maintaining) sleep, increased rate of body movements during sleep, and frequent awakenings with psychic and somatic panic that is not necessarily associated with dreaming (3-5).

However, although subjective reports of sleep disturbances are prominent features of PTSD, laboratory studies have provided inconsistent evidence of objective sleep disturbances, as monitored in the laboratory or with ambulatory monitoring (6). Some polysomnographic (PSG) studies, indeed, found longer sleep latencies, reduced total sleep time, and lower sleep efficiencies among patients with PTSD (1, 7-9). However, most other studies failed to replicate these findings (3, 10-16). Thus, overall, data from these studies do not support a dramatic and consistent adverse effect of PTSD on objective sleep measures, as could be expected from the sleep complaints of these patients.

Further support for these findings came from several studies that evaluated objective measures of sleep in PTSD patients in their natural environment at home using actigraphic monitoring. The main advantage of this method is in-home study of sleep, for several days, with minimal discomfort and disruption to the patient's life routine. Dagan et al. (10) found no significant differences on actigraphic measures between a group of war-related PTSD patients and a group of matched controls. Klein et al. (17), in a prospective design, did not find significant differences between traffic accident victims who did or did not develop PTSD during the first year after the accident.

Interestingly, sleep laboratory studies that examined depth of sleep even contradict subjective complaints of insomnia in PTSD. Schoen et al. (18), for example, found significantly higher awakening thresholds, in both REM and non-REM sleep, among Vietnam veterans with and without disturbing nonREM dreaming. …