Insomnia and alpha sleep in chronic non-organic pain as compared to primary insomnia

A considerable proportion of chronic non-organic pain patients suffer from insomnia, and alpha sleep has been suggested to be specifically associated with fibromyalgia. However, the clinical significance of those symptoms is not clear. This study was carried out to investigate this question. Twenty-six middle-aged, non-organic pain patients complaining of persistent insomnia were compared with 25 chronic primary insomniacs in a polysomnographic investigation. Alpha sleep was measured by automatic EEG analysis. A postsleep inventory allowed a separation of those pain patients with actual pain in the recording night to examine its possible influence on sleep. Both groups of patients displayed severe disturbance of sleep maintenance. The pain group did not differ in any of the insomnia variables or in sleep stages from chronic primary insomniacs. The occurrence of alpha sleep was high in either group which suggests that this is not a phenomenon specifically related to pain syndromes. A comparison of the pain subgroups revealed no difference between those with or without actual pain in the recording night. It is concluded that insomnia in chronic pain is of the same type and degree as primary insomnia. Apparently, the chronic process made insomnia so persistent that there was no response to actual night-time pain. Our study suggests that the interpretation of insomnia as secondary to pain, as it is usually made by the pain patients themselves, is a misattribution. It is suggested that insomnia in chronic pain patients should be taken seriously and treated by its specific methods.