The physician treating either pain or sleep disorders is familiar with the comorbidity of complaints in the two domains. Inasmuch as sleep disturbances and pain each occur in a sizable proportion of the population,1,2 it is to be expected that they would co-occur with some frequency even in the absence of mutual influence or common cause. However, estimates of their comorbidity3,4 far exceed such expectations, and it is clear from both controlled experimentation and observational data that difficulty in one domain predisposes to difficulty in the other.
Whether the relationship between pain and disordered sleep is causative or coincidental for any given patient, it is beneficial for the pain physician to be acquainted with ameliorative strategies for impaired sleep and to know when to refer the patient to a sleep specialist. In the context of pain treatment, improved sleep may decrease pain per se, enhance the patient's ability to cope with pain, and confer long-term benefit on physical and mental health.5-9 In some cases it may prevent development of chronic pain in acute-pain patients,10 and may prevent regional pain from becoming more widespread.11 Preventing, mitigating, or interrupting the influence of disturbed sleep on pain, or a vicious cycle in which pain and sleeplessness exacerbate each other, may not only benefit the individual, but also reduce lost-productivity costs to society.
Cognitive-behavioral interventions have long played an important role in the treatment of sleep disorders, and a developing body of research supports their efficacy in improving sleep in a pain population. Although studies of cognitive behavior therapy (CBT) for disordered sleep in patients with pain have focused on insomnia, there are a number of other sleep disturbances for which CBT is deployed in the general sleep-disordered population. The application of CBT to conditions other than insomnia, even if as yet unstudied specifically in the context of pain, bears some explication. Specific conditions (e.g., apnea) are known to exacerbate pain,12 so their treatment might diminish the intensity and duration of pain. In addition, there is no a priori reason to surmise the failure of such techniques in patients with pain, especially considering that time-intensive and sometimes complex regimens for insomnia have been successfully applied in that population.5,13-16
CONFLUENCE OF PAIN AND SLEEP DISTURBANCE
The epidemiology of sleep disorders is complicated by a history of discrepant definitions of the most common disturbance, insomnia, estimates of whose prevalence range from 4% to 48% depending upon the stringency of defining criteria.17,18 Sleep-disordered breathing and restless legs syndrome are the next most prevalent conditions.1 At least one-third of the population is generally reported to suffer from some degree of sleep compromise and/or daytime sleepiness, and one out of ten to experience a clinically significant sleep disorder.1 Estimates of the prevalence of chronic pain similarly ...