Pain-related insomnia versus primary insomnia: a comparison study of sleep pattern, psychological characteristics, and cognitive-behavioral processes.

BACKGROUND: Recent applications of cognitive-behavior therapy for primary insomnia in the management of pain-related insomnia are based on the implicit assumption that the 2 types of insomnia share the same presentation and maintaining mechanisms. The objectives of this study were to compare the characteristics of patients who have pain-related insomnia with those reporting primary insomnia and to identify psychological factors that predict pain-related insomnia. METHODS: Chronic pain patients with concomitant insomnia (n=137; Pain-related Insomnia Group) completed a selection of questionnaires that measure sleep patterns, psychological attributes, and cognitive-behavioral processes associated with the persistence of insomnia. Their responses were compared with those of primary insomnia patients (n=33; Primary Insomnia Group), using 3 sets of multivariate analyses of covariance that took account of demographic differences. Hierarchical regression analyses were performed to identify predictors of insomnia severity among the chronic pain patients. RESULTS: The Pain-related Insomnia Group did not differ from the Primary Insomnia Group in their pattern and severity of sleep disturbance. The 2 groups were largely comparable in terms of their psychological characteristics, except that the Primary Insomnia Group was distinguishable from the Pain-related Insomnia Group by their greater tendency to worry. Patients in the Pain-related Insomnia Group reported levels of sleep-related anxiety and presleep somatic arousal that matched with those reported by patients in the Primary Insomnia Group. However, relative to patients in the Pain-related Insomnia Group, those in the Primary Insomnia Group reported more dysfunctional sleep beliefs and presleep cognitive arousal. In addition to pain intensity, depression, and presleep cognitive arousal were significant predictors of insomnia severity within the Pain-related Insomnia Group. CONCLUSIONS: There are more similarities than differences between the 2 types of insomnia. Besides pain, mood, and presleep, thought processes also seem to have a role in the manifestation of pain-related insomnia. It is suggested that hybrid treatments that seek to simultaneously address factors across these domains may represent more effective treatments than 1-dimensional interventions.