Emotional modulation of pain and spinal nociception in persons with severe insomnia symptoms.

Abstract

Impaired sleep enhances pain, perhaps by disrupting pain modulation. Given that emotion modulates pain, the present study examined whether emotional modulation of pain and nociception is impaired in persons with severe insomnia symptoms relative to controls. Insomnia group (n = 12) met the International Classification of Diseases, tenth revision symptoms for primary insomnia and controls (n = 13) reported no sleep impairment. Participants were shown emotionally evocative pictures (mutilation, neutral, and erotica) during which suprathreshold pain stimuli were delivered to evoke pain and the nociceptive flexion reflex (NFR; physiological correlate of spinal nociception). Emotional responses to pictures were similar in both groups, except that subjective valence/pleasure ratings were blunted in insomnia. Emotional modulation of pain and NFR was observed in controls, but only emotional modulation of NFR was observed in insomnia. Consistent with previous findings, pain modulation is disrupted in insomnia, which might promote pain. This may stem from disrupted supraspinal circuits not disrupted brain-to-spinal cord circuits.