1. Abstract  Fibromyalgia (FMS) is a chronic syndrome of widespread pain and fatigue;  Here, it is hypothesized, that this disorder is explained by the Dissociated States (DS) concept.  Objectives: -to identify sleep DS, both in NREM and REM -to provide data for sleep electroencephalogram (EEG) mapping abnormalities both in specific sleep stages and across sleep stages (this analysis will be performed by computing sleep EEG mapping in the conventional frequency of bands - , ,  1,  2,  and  ). Dissociated States in Fibromyalgia RecPad2010 - 16th edition of the Portuguese Conference on Pattern Recognition, UTAD University, Vila Real city, October 29th T.F.Oliveira 1,2,4, L.Ferreira 2,3, Teresa Paiva 2,4 and J. Miguel Sanches 1 1 Institute for Systems and Robotics / Instituto Superior Técnico, Lisboa, Portugal 2 Centro de Electroencefalografia e Neurofisiologia Clínica, Lisboa, Portugal 3 Laboratório EEG Sono (CHLN -HSM) 4 Faculdade de Medicina da Universidade de Lisboa, Lisboa, Portugal Background FMS is a disorder of unknown aetiology which occurs in 3-4% of the general population, 80- 90% are females (ACR). FMS patients suffer from severe fatigue, sleep disturbances, morning stiffness, cognitive problems, affective disturbances, multiorgan dysfunctions and other symptoms (anxiety, depression, sensory hypersensitivity). Alternatively, FMS is a psycho-neuro-endocrine-immune disorder, so it has an organic basis. However the biological markers are still not found. Clinical assessment of FMS brings to light the inconsistency between the severity of complaints and the lack of explanatory biological markers, which in our opinion can be explained by a central nervous system (CNS) dysfunction, via DS, and must be investigated. Considering this, we hypothesize as a basic general mechanism, the concept of DS, which can take several forms. Dissociated States (DS) A DS is a state that gathers characteristics from two functional states that shouldn’t coexist. A clear example of that is alpha-delta sleep pattern. The presence of alpha rhythm pattern is typical from awake disappearing at sleep onset, while delta EEG patterns are characteristic of sleep. In FMS these two features coexist reflecting a “sleeping-awake” state. What is common? What are we looking for? K-complexes transitory events observed in central electrodes which last between 0,5 and 2 seconds Spindles transitory activity bursts, observed in central electrodes (12-15 Hz) NREM Sleep Saw-tooth like waves (e.g. theta rhythm) – normally associated to rapid eye movements Rapid eye movement with muscular atonia REM Mioclonies sudden and very brief muscle contractions REM Sleep Alpha activity (8 - 13 Hz) Caracteristic from awakeful states Alpha activity 1.REM events occurring during NREM 1.2. Saw tooth like waves 1.2. Rapid eye movements 1.3. Mioclonies Methods 12 FMS patients + 12 healthy controls Ages 30 to 58 years Nocturnal polysomnography (PSG) at sleep laboratory (19 EEG channels + conventional PSG data) 2.NREM events occurring during REM 2.1. Spindles 2.2. K- complexes 3.Alpha activity in REM and NREM Funded by: FCT PRAXISXXI/BD/36746/2007 & FCT PTDC/SAU-BEB/104948/2008