Co-morbid Sleep-Disordered Breathing
Krakow et. al. (2001) found that treatment on Co-morbid sleep disordered breathing (SDB) on patients with nightmares and PTSD is helpful in reducing the nightmare incidents. The two most common types of SDB are are obstructive sleep apnea (OSA) and upper airway resistance syndrome (UARS). Both OSA and UARS produce a final common pathway of multiple awakenings or micro-arousals from sleep, secondary to the breathing disturbance; this causes sleep fragmentation, poor sleep quality and subjective complaints of daytime fatigue and sleepiness.
There is no published study that links the relationship SDB and patients with nightmares or PTSD. However, in a recent study 81 out of 156 sexual assault survivors with nightmares, insomnia and PTSD endorsed key symptoms consistent with a sleep breathing disorder, as defined by clinical algorithm. A potential relationship between SDB, trauma and dreams is also suggested by the case of a Vietnam veteran with a 20 year history of nightmares and PTSD, which following diagnosis of co-morbid sleep apnea, resolved with continuous positive airway pressure (CPAP). Therefore Krakow conducted a study on 23 patients with chronic nightmare disorder (15 with PTSD) who were subsequently diagnosed with SDB. In the study they indeed found an improvement in sleep, daytime well-being, nightmares and PTSD syndrome. Hicks suggests that SDB-induced nightmare sufferers are more likely to recall nightmare than those who do not. Therefore CPAP therapy, by enhancing sleep consolidation, may reduce awareness of bad dreams as well as day-time distress related to nightmares. Although this is still a small sample study the result suggest that SDB treatment can be used as a useful interventions for appropriate patients.
In Krakows subject group about 30% of them suffered UARS. UARS is frequently observed in individuals who possess specific cranio-facial features (small, recessed chin; thickened posterior third of the tongue; excessive soft palate tissue; and high, arched or narrow hard palate) that yield a smaller airway; however, assessment of UARS on standard polysomnography or EEG may only exhibit excessive micro-arousal activity without obvious airflow irregularities. This subtle facet of UARS coincides with similar polysomnographic and sleep EEG findings of increased micro-arousal activity in nightmare and PTSD patients. Yet, none of these studies have monitored for the presence of UARS or reported on subtle respiratory irregularities, and most, importantly, none have assessed the impact of CPAP on these patients. Hence UARS are prevalent in crime victims with PTSD. Overall, sleep breathing disturbances appear to be associated with psychological sequelae, such as post-traumatic stress and nightmares; and, chronic sleep fragmentation may be fundamental to this process.
Krakow proposed a trauma-centered hypothesis, trauma might have the capacity to affect the airway through psycho-physiological pathway that promote OSA or UARS. They back up their hypothesis by research indicating a higher prevalence of obesity in sexual assault survivors. Hypothetically, a trauma survivor who developed an eating disorder causing marked weight gain could develop SDB. Obesity can be used as an important predictor of SDB and obesity without SDB has also been associated with daytime fatigue and sleepiness.
First, obstructive airway disease including SDB, snoring, asthma, and chronic obstructive pulmonary disease have all been associated with nightmares; and both nightmare and SDB have been associated with anxiety. Thus, improved airflow with CPAP may decrease nocturnal anxiety that might be related to respiratory distress; and this in turn night decrease nightmares. Krakow et. al. also report that normalization of oxygenation through improved airflow may have a direct therapeutic effect on nightmares and PTSD or nocturnal anxiety in general.
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