Sleep in fibromyalgia patients: clinical and polysomnography pattern.

Fibromyalgia syndrome is a common chronic pain syndrome that is often assoc iated with sleep disturbances characterized by subjective experience of non -restorative sleep. The complaints of sleep disturbances are correlated wit h polysomnographic features clear abnormalities in the continuity of sleep as well as in the sleep architecture. Sleep-recording abnormalities are cha racterized by a reduced sleep efficiency with increased number of awakening s, a reduced amount of slow wave sleep and an abnormal alpha wave intrusion in non rapid eye movement, termed alpha-delta sleep. These data were confi rmed by spectral analysis of sleep showing an increased EEG power density i n the higher frequency band and a reduced EEG power density in the lower fr equency bands. Moreover, other microstructural aspects of sleep were modifi ed with high frequency of arousals and alpha-K complex reported, both indic ators of fragmented sleep. The fibromyalgia symptoms may relate to a non-re storative sleep disorder associated with the alpha-EEG sleep anomalies. How ever, alpha-EEG sleep anomaly is non-specific for fibrositis, also seen in normal controls during stage 4 sleep deprivation. Moreover, fibromyalgia pa tients may also experience primary sleep disorder such as sleep apnea or pe riodic leg movements. The etiology of this common condition is incompletely understood and the existence of a specific entity of fibromyalgia is still a matter of debate. However, several studies have found abnormal brain met abolism of substances such as serotonin implicated in sleep arousal and pai n mechanisms and administration of tricyclic antidepressants and selective serotonin reuptake inhibitors may be useful in fibromyalgia. Pain, poor sle ep quality and anxiety may contribute to the clinical picture. Several fact ors such as psychological, environmental, genetic factor, altered serotonin metabolism and altered sleep physiology are involved in the pathogenesis o f fibromyalgia. (C) 2001 Editions scientifiques el medicales Elsevier SAS.