Earlier this year, I joined with other experts in the field who are researching comorbid insomnia and sleep apnea—something we describe as “complex insomnia”—to deliver a symposium in Bologna, Italy at the annual European Sleep Research Society (ESRS) conference. The talks were attended by a few hundred participants and were well-received, although candidly I want to emphasize this topic remains too far out on the cutting edge and many sleep researchers and other sleep professionals still show difficulty digesting the clinical relevance and importance of this extremely common co-morbidity. I base this view anecdotally on the audience Q & A generated after each talk, which I believe showed little curiosity and even less in the way of corroborative experiences. Nonetheless, the symposium will hopefully prove to be a good start in raising our colleagues' awareness and planting new seeds of discovery.
Each talk and related Q & A lasted about 30 minutes. Dr. Christian Guilleminault at Stanford (my former mentor during a sleep fellowship in 1993) kicked things off with a talk entitled “The early recognition of co-morbid obstructive sleep apnea and insomnia.” Dr. Guilleminault’s presentation was inspiring and emotional in light of his recognition of the likely connections between sleep breathing and insomnia in the early 1970s (40+ years ago). During part of this period he was training as a medical resident in Bologna, so we can only imagine how emotional the experience was for him to give this talk. Back then, he noted a connection between central sleep apnea and insomnia, and he collaborated on three different papers on the topic, which were all published in the early to mid- 1970s in prestigious scientific journals.
Oddly, this research topic all but vanished from the scientific literature until the late 1990s and early 2000s when a few papers noted the finding of occult sleep apnea in a few different samples of patients. Dr. Leon Lack, who chaired the conference as well as serving as the 4th and final speaker, noted this large gap in the literature, while introducing the next talk on our own work in the field dating back to 1999, “Positive airway pressure to treat co-morbid insomnia and sleep-disordered breathing: a rationale for advanced auto-adjusting dual pressure technology.”
I pointed out that our original spark of knowledge on comorbidity derived from our work with chronic nightmare patients with PTSD. Their intense and complex sleep disorders turned out to be due to additional factors beyond their self-reported complaints of insomnia and nightmares. In 2001, we published the “Complex Insomnia” paper in Biological Psychiatry, demonstrating a 90% rate of OSA/UARS in crime victims with PTSD. The second half of my talk delved into our experiences using advanced PAP technology, notably ABPAP and ASV, in the treatment of complex insomnia patients and how we were not only achieving higher use rates with these devices, but also these modes of PAP were strongly associated with marked improvements in insomnia severity. I closed with a few slides describing preliminary results in our current randomized controlled trial comparing CPAP vs ASV in complex insomnia patients.
Dr. Erla Bjornsdottir from Iceland delivered the third talk: “Insomnia phenotypes response to obstructive sleep apnea treatment in co-morbid insomnia/OSA.” Dr. Bjornsdottir raised very interesting questions about the impact of OSA treatment on different types of insomnia, generally classified as the sleep onset category (SOI) sleep maintenance (SMI), and early morning awakenings (EMA). In her research group, they found clear evidence for improvement in SMI with CPAP treatment but far less impact on the early or late varieties of insomnia. She then went on to described a very clinically relevant research project about to get underway at her center in which they will assess the impact of online psychological insomnia treatment (cognitive-behavioral therapy for insomnia, CBT-I). Their innovative study will examine a series of patients who will have all been diagnosed with OSA, but due to wait times for patients to return for retitrations and PAP setups, they will be use the intervening time to evaluate how such patients respond to CBT-I. All these patients will have been diagnosed with OSA, but during this waiting period only some will receive insomnia treatment. In other words, the research is an excellent test on whether or not CBT-I will decrease insomnia symptoms in patients with OSA before they are exposed to a CPAP treatment that might also decrease insomnia severity. This type of research is known as a dismantling study in the sense that if someone received CPAP and CBT-I, we would expect a very potent result. Instead, by focusing on just CBT-I, we might learne how much improvement can be achieved for insomnia symptoms before the OSA itself is treated.
Dr. Leon Lack from Australia delivered the fourth talk: “Treatment of insomnia before CPAP for co-morbid insomnia/obstructive sleep apnea,” and as you can see by the title, their work overlaps with Dr. Bjornsdottir’s up and coming study. Dr. Lack has previously presented on this important topic at an annual SLEEP conference in the USA, if memory serves more than 10 years ago. He described how the comorbid presence of OSA in one group of insomniacs compared to a group of insomniacs without OSA yielded no differences between the groups when treated with CBT-I. Recently, Dr. Lack and his graduate student colleague, Alexander Sweetman have published two thorough review articles on comorbid insomnia and OSA, the first, “Diagnosis and Treatment of Insomnia Comorbid with Obstructive Sleep Apnea” discusses how often insomnia in sleep apnea patients is undiagnosed, undertreated or untreated and how CBT-I in addition to improving insomnia may demonstrate value by increasing PAP adherence. The second article, “Developing a successful treatment for co-morbid insomnia and sleep apnoea” emphasizes the confusion currently in the literature on the best approach to treat patients with this condition, which they dubbed COMISA (i.e. comorbid insomnia and sleep apnea). Dr. Lack concluded his talk by describing further work to examine the timing of CBT-I in these patients.
Prior to the talk, several of us met for dinner to discuss our perspectives on comorbid insomnia and sleep apnea. Another young researcher in this area, Dr. Megan Crawford joined us and contributed to our conversation. Just in the past few years, she has co-authored papers with Dr. Jason Ong, another insomnia/sleep apnea researcher. Their three works include: 1) “Insomnia and Obstructive Sleep Apnea” ; 2) “Management of Obstructive Sleep Apnea and Comorbid Insomnia: A Mixed-Methods Evaluation”; and 3) "Evaluating the treatment of obstructive sleep apnea comorbid with insomnia disorder using an incomplete factorial design."
One of the most revealing aspects of the discussion was the nearly universal belief of a widely underestimated prevalence of complex insomnia (as we call it) or COMISA (as penned by the Australian group) or simply comorbid insomnia (as described commonly by sleep researchers and clinicians). Although rates varied to a low of 40% and a high of 90%, all these proportions are very high and probably not widely accepted by the typical sleep doctor or even someone who specializes in insomnia research. Nonetheless, while rigorous protocols to detect accurate prevalence rates remain to be completed, it will be revealing when it is determined whether or not all of us in the trenches are over-estimating the frequencies because we are too close to these types of patients or whether we will prove more accurate because we are paying closer attention to the phenomenon.