Prevalence of Insomnia Symptoms in Patients With Sleep-Disordered Breathing

Barry Krakow, MD, Dominic Melendrez, PSG-T, Emily Ferreira, James Clark, Sleep and Human Health Institute, Albuquerque; Teddy D. Warner, PhD, Department of Psychiatry, University of New Mexico School of Medicine, Albuquerque, NM; Brandy Sisley, Sleep and Human Health Institute, Albuquerque; David Sklar, MD, Emergency Medicine, University of New Mexico School of Medicine, Albuquerque, NM


CHEST. 2001;120(6) 

In This Article


In a university sleep-disorders clinic, insomnia symptoms were widely prevalent in a representative sample of objectively diagnosed SDB patients with OSA or UARS. Patients with SDB and insomnia suffered from more physical and mental symptoms and psychiatric disorders, all of which might contrib ute to or exacerbate insomnia complaints.[28,29,30] In addition, 37% of study patients received sedating and/or psychotropic medications, and SDB-plus patients accounted for twice as many medication users as SDB-only patients. Although this study did not examine SDB treatment compliance, it will be important to determine to what extent sleeplessness influences the use of CPAP or oral airway devices in patients with SDB and insomnia. We predict that those with greater insomnia complaints have greater difficulty adapting to sleep breathing medical equipment because they spend too much time awake and aware of the devices.[17] Sleep hygiene and cognitive-behavioral treatments[31] and/or judicious use of sedatives for the treatment of insomnia might prove instrumental in facilitating adaptation to CPAP or airway appliances for such patients. However, it remains to be seen how such a clinical program would operate in a sleep center working under managed-care pressures.

It is worth noting that SDB processes may also cause, exacerbate, or otherwise contribute to insomnia.[3,4,8,9,10,11,12,13,14,15,17,18,19,20,21,31,32,33,34] This may occur through the development of psycho-physiologic conditioning in response to repeated awakenings, which in turn could lead to frustration and dissatisfaction with sleep behaviors.[1,31] This may promote further ruminations about sleep and subsequent sleep onset or maintenance insomnia.[1,31] Interestingly, a study employing nasal pressure transducer technology[16] reported a surprisingly high rate of SDB in a select group of crime victims seeking treatment for insomnia,[18] and subsequent CPAP treatment yielded marked insomnia improvement in some of these patients.[34] Nonetheless, "CPAP for insomnia" would seem like a nonstarter. In our clinical and research experience, insomniacs can successfully adapt to CPAP, but the resources needed to facilitate the use of the breathing mask in an insomniac with SDB requires a threefold increase in time and effort compared to a classic OSA case.

The relationship between insomnia and SDB remains unclear. It is important to clarify why some patients with recurrent SDB awakenings suffer from insomnia whereas others do not. A thorough chronology of the inception of sleep disorders in such patients may provide clues to a potential bidirectional relationship between SDB and insomnia. Or, perhaps SDB patients with greater symptom distress from whatever causes are simply at greater risk for developing comorbid insomnia. While it seems probable that SDB could exacerbate insomnia complaints through varying patient response to sleep fragmentation and poor sleep quality, it is less certain how insomnia might exacerbate SDB. Speculatively, sleep fragmentation that is commonly associated with insomnia may worsen SDB through greater exposure to less stable, lighter stages of non-rapid eye movement sleep (stage 1) or through fragmentation effects on upper-airway muscle tone.[35] Conversely, decreased REM sleep, also commonly observed in insomnia, may protect this type of patient from even worse SDB by decreasing exposure to the greater airway collapsibility associated with REM physiology.[36]

It is noteworthy that the two groups were very similar in their sleep breathing complaints and averaged similar BMIs, minSao2 , snoring patterns, and AHIs (both groups averaged severe indexes). Thus, to identify SDB-plus patients prior to polysomnographic evaluation requires a complete sleep history to evaluate insomnia symptoms and their impact on overall sleep dysfunction. Furthermore, in light of the markedly reduced mean sleep efficiencies reported in the SDB-plus group, it may be prudent to address sleep consolidation needs with behavioral methods before such patients undertake a CPAP titration or prior to their subsequent use of CPAP or oral appliances. Failing to educate or treat the patient with sleep hygiene maneuvers or advanced cognitive-behavioral therapies to consolidate sleep might be associated with CPAP noncompliance. Admittedly, treating such patients is time-consuming and difficult in a managed-care setting, particularly if there is an expectation that most SDB cases would follow the classic textbook description in which the patient is sleepy and has no insomnia complaints.

While the preceding discussion may seem axiomatic to some sleep specialists, more pulmonary medicine and critical care specialists are becoming involved in clinical sleep medicine,[37] and it is unknown to what extent such providers receive training in the treatment of insomnia. Our objective is not to impugn the work of pulmonologists, a specialty group that brings substantial expertise and perspective to the field of sleep-disorders medicine. However, it has been noted[38] that pulmonary sleep specialists may have greater difficulty in managing nonpulmonary cases, although, there is no extant literature on pulmonologists' capacity to treat insomnia symptoms. To be sure, a university environment might attract more complex sleep-disorders patients. Not-withstanding, if SDB treatment compliance were linked inversely with comorbid insomnia in some proportion of patients, sleep medicine practitioners, including pulmonologists, will need proper training or experience in the use of sleep hygiene and other cognitive-behavioral strategies in the management of insomnia. As sleep medicine continues its evolution toward a multidisciplinary specialty, such expertise will be required routinely.[10,39]

Primary care physicians also have an important role to play in this process because they must be able to distinguish insomnia patients with SDB who need referral for polysomnography from insomnia patients without SDB who require other forms of treatment. Similarly, mental health practitioners who treat insomnia patients referred by other physicians must also consider the potential for undiagnosed SDB in their patients, particularly when pharmacotherapy or psychotherapy are ineffective in ameliorating insomnia symptoms. As such, it would be equally important to determine whether practicing psychiatrists and psychologists, specializing in insomnia treatment, receive appropriate training and experience in the assessment of SDB. These complex symptom presentations may be especially difficult to assess because certain SDB patients with severe insomnia, like the subset of 20 patients in our sample, describe such overarching episodes of sleeplessness that attention is diverted away from a potential SDB diagnosis. More active consideration of SDB in the differential diagnosis of insomnia will improve the capacity of all clinicians to identify these complex cases and to distinguish those who need polysomnography.

Generalizability of these findings to other environments is limited because data were collected from a single university sleep clinic, which may have disproportionately attracted more complex cases. The clinic also does not employ standardized insomnia instruments to measure insomnia severity. Therefore, it is unknown from this study the extent to which these comorbid insomnia symptoms were clinically relevant in these patients and how they might affect SDB treatment and other patient outcomes. The temptation may be to assume that these findings are epiphenomenal or coincidental and therefore clinically insignificant; however, such perspectives are probably a function of so little research having been conducted on patients with both insomnia and SDB. Regardless, no definitive practice parameters can be offered based on this study, although we anticipate that additional research in this area will confirm that SDB and insomnia co-occur frequently, and that each disorder has important influences on the other condition and on overall treatment success. Treatment studies measuring CPAP or oral airway device compliance with and without concurrent insomnia treatment for this type of SDB patient will provide greater clinical insights into these complex sleep-disorders cases.

In summary, 50% of a representative sample of SDB patients appeared to have clinically substantive insomnia symptoms; of these 116 cases, 20 patients presented with chief complaints of insomnia only. For patients with insomnia and SDB, assessment and treatment is likely to be more time intensive if appropriate therapeutic regimens were to be provided for both sleep disorders. In the current climate of managed-care medicine and its impact on sleep-disorders centers and laboratories, it remains to be seen whether or not these complex patients are receiving the proper amount and quality of care.


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