Abstract Preparation for the 2016 Annual SLEEP Conference: Part II

The three PTSD related aspects mentioned at the close of Part I introduced the topics of how to help these patients use PAP therapy more regularly, how PAP therapy may provide a treatment for their nightmares, and how sleep disorders in general may factor into one of the three core symptoms of PTSD, known as avoidance behavior.

From many other posts, you know that we often observe expiratory pressure intolerance when attempting use of standard CPAP devices in our population of mental health patients.   As PAP settings are increased to eliminate RERAs, susceptible patients report difficulty breathing out against the air coming in. In the worst case, a patient may swallow air and end up with considerable bloating, gas, and pain in the stomach by morning. In our experience dual pressure or bilevel devices reduce much of this problem for the simple reason that the patient receives a lower pressure level when exhaling compared to the fixed CPAP device, which delivers the same pressure in and out. 

In looking over research studies on the topic of CPAP compliance in PTSD patients, there are few studies. Nonetheless, some studies clearly point to lower than typical compliance rates routinely described in the sleep literature.   For example, it is not uncommon to see reports of 50% of patients compliant with CPAP in many non-PTSD studies, but it is not very common to find this proportion of success in PTSD patients. Very recent research suggests 30% might be a more accurate estimation of compliance.

In our abstract that looked at a medium-sized sample (between 50 and 100 PTSD cases with co-morbid OSA/UARS), these patients all failed CPAP therapy due to the pressure intolerance or lack of substantial benefit. We manually titrated them in the sleep lab with the dual pressure, auto-adjusting technology (e.g. ABPAP or ASV) and were able to demonstrate a 50% rate of compliance in our sample. Unfortunately, these pressure modes are more expensive in certain geographical areas, so some sleep specialists are reluctant to try out these devices with their PTSD patients. Regardless, at some point prices will come down as these advanced pressure modes are demanded by more patients. In the meantime, it is encouraging to know that for PTSD patients struggling with a standard CPAP device, a more advance PAP technology might make adaptation at least a 50-50 proposition.

Nightmares are the next area we studied. As reported in prior posts, a few research groups have observed reductions in nightmares with the use of PAP therapy, and in one study, nightmare reductions were clearly associated with improved levels of PAP compliance (more nights used). Technically, however, compliance is not an equivalent metric of the actual hours per night of PAP use, and we elected to analyze this aspect in two small groups of nightmare patients who were either compliant or below compliant levels of use. 

Both groups represented individuals with elevated DDNSI scores, which is our Disturbing Dreams and Nightmare Severity Index, a scale that is widely in use for conducting assessment and treatment studies on chronic nightmare patients. The DDNSI measures how often a person reports nightmares per week (i.e. how many nights per week), how many actual nightmares per week, how often nightmares cause awakenings from sleep, a rating for the severity of nightmares, and a rating for the intensity of nightmares. With these five measures, a person could score from 0 to 37 on the scale, and we have found that patients who score 10 or higher are almost always suffering from a chronic nightmare disorder.

In our study, we looked more specifically at hours of use in the two groups to determine whether or not a correlation existed between these hours and decreases in nightmares. In the first step, we divided the groups into the compliant and noncompliant groups and then examined their intake DDNSI scores against their most recent follow-up scores. All the nightmare patients started out with scores above 10, but the compliant group dropped the DDNSI to scores well below 10; whereas, the noncompliant group only dropped scores just below 10. From this information alone, it was clear that the greater use of PAP therapy was associated with greater drops in nightmare frequency and severity. 

A substantial proportion of patients actually made the link between using the PAP device and the decrease in nightmares. These statements do not prove that PAP was the cure for their bad dreams, but it is nonetheless of clinical and practical interest that many people speculated that the PAP device was treating their nightmares as well as their sleep-disordered breathing. Last, we ran a statistical correlation that demonstrated a significant association between the precise number of hours used by each patient and their exact decrease in their nightmare scores on the DDNSI.

This statistical test does not prove PAP treatment was causing the nightmares to lessen, but when associations of this type are consistently found, then it motivates researchers to conduct more sophisticated studies, such as prospective designs, in which nightmare patients are divided into two groups, say one with PAP and one with a drug (Prazosin) to treat nightmares to compare the impact of each treatment. Since Prazosin is now a proven drug for the treatment of chronic nightmares, it serves as an excellent comparison treatment, because in head to head competition with PAP, we would be able to learn to what extent, if any, PAP therapy decreases nightmares.  

These types of randomized controlled trials (RCT) are the highest levels of evidence and permit us to use terms like “cure” or “effective treatment” instead of having to say “associated with improvement.” More research in this area should look for other comparisons as well, particularly in patients treated with imagery rehearsal therapy, the highest rated non-pharmacologic nightmare treatment in the scientific literature. Again, an RCT comparing PAP to IRT would also clarify more precisely the impact of PAP therapy on chronic nightmares.

The third and final abstract dealt with a much more complex issue seen in PTSD patients known as avoidance behavior. In PTSD, patients often suffer three major clusters of symptoms. Although the fields of psychiatry and psychology have recently changed some of the criteria for PTSD, it is still much easier to explain the diagnosis based on these symptom clusters known as the following:

  • intrusion or re-experiencing describes when trauma survivors suffer from nightmares that remind them of the trauma, such that they are intruding into their consciousness
  • arousal describes how a symptom like nightmares and the related reminders of the trauma cause the individual to become aroused, on guard or hypervigilant as if the reminder is a signal that the trauma might be re-occurring or is anticipated to happen again
  • avoidance describes the types of behaviors an individual will do or not do to avoid any sort of reminder that would then trigger the cycle of intrusions and then arousal; the most classic sleep-related cycle that perfectly explains nightmares would be someone who eventually develops insomnia; the constant triggering of nightmares “teaches” the person to stop going to sleep as the best way to avoid nightmares (the initial trigger of the cycle). 

The question we raised at our center was whether or not avoidance behavior could be associated with fatigue or sleepiness. Examination of an avoidance subscale on a PTSD checklist shows a number of what might be deemed “energy-related” questions as in when a trauma survivor avoids going to places that remind him or her of the traumatic events, is it the trauma causing the avoidance or could the individual simply feel a low energy state of being too tired or sleepy to engage in the activity? 

To find out this information, we used a commonly used PTSD checklist that poses seven avoidance questions and inserted sub-questions about trauma, fatigue and sleepiness. So, when the individual answers the question about “are you not interested in doing things you used to enjoy,” three consecutive sub-questions inquire whether trauma or fatigue or sleepiness contributes to this feeling of disengagement from the normal routine. 

Our findings surprised us, because all the answers were very similar, that is, for each avoidance question, patients generally marked that the unique influences of trauma or fatigue or sleepiness were nearly identical in terms of how much each one contributed to the problem. Now, clearly, as patients coming to a sleep center are more apt to suffer from fatigue or sleepiness, there is probably some degree of bias exists in our sample of patients (by the way, this is called selection bias). However, while these patients are more likely to suffer from fatigue or sleepiness, we would not have expected them to make so strong a link between the avoidance behavior and fatigue and sleepiness.

We would say the jury is not just out on this one, but rather the jury has only begun deliberations. Still, it is such a tantalizing theory to think that underlying sleep disorders contribute to the symptoms of fatigue and sleepiness in PTSD patients beyond such symptoms being generated by the posttraumatic stress process itself.

In sum, PTSD represents a fruitful area of exploration in the realm of comorbid sleep disorders. Comprehensive research shows that these patients suffer from nightmares, and mounting evidence shows they also suffer from sleep-disordered breathing. Therefore, it would not be surprising to find that more evidence will emerge on the prevalence of sleep disorders in PTSD patients. Moreover, their use of many validated therapies may not only improve their sleep disorders, but also improve their PTSD.   Finally, once more in-depth research examines these possible connections, we are more likely to discover more precise understanding of the relationships between sleep and PTSD.    

Barry Krakow MD


Dr Krakow’s 27 years of sleep research have focused on the complex relationship between physiological and psychological sleep disorders. Dr Krakow currently operates private sleep medical center, Maimonides Sleep Arts & Sciences, Ltd., and serves as Classic SleepCare’s paid Medical Director.

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