Cognitive mechanisms in comorbid insomnia and chronic pain
The present study examined the relation between pain catastrophizing, pre-sleep arousal (PSA), and insomnia severity in chronic pain patients. Forty-eight outpatients with chronic pain (duration of 6 months or more) completed self-report measures of health, mood, pain, and sleep. A hierarchical regression analysis was conducted to determine the relative contributions of pain catastrophizing, cognitive PSA, and somatic PSA to the prediction of scores on the Insomnia Severity Index, while controlling for age, sex, education level, depression severity, symptoms of Restless Legs Syndrome (RLS), and pain intensity. Results showed that pain catastrophizing accounted for unique variance in insomnia severity, independent of pain intensity and other control variables. However, when cognitive and somatic PSA were taken into account, the significance of cognitive PSA rendered pain catastrophizing non-significant. Research and clinical work should explore how cognitive variables (such as pain catastrophizing) may be linked to the pre-sleep arousal in comorbid insomnia.