Sleep, pain and breathing have a complex multidimensional relationship. Pain disturbs sleep, poor sleep alters the perception of pain and sleep is a vulnerable state of breathing. The central system sensitization affecting the sensation of widespread pain in FM is due to a decrease in the neurophysiologic inhibition of perception of painful stimuli. This is caused by disturbed sleep. Rheumatic disease pathology can be understood in the light of the interference of cytokines and cellular immune functions with the sleeping/waking brain. Sleep disturbances such as unrefreshing sleep, difficulty falling asleep and frequent night awakenings have been reported by over 90% of FM patients. Sleep disturbances may be related to depression through pain and alteration of physical functioning. Depression and sleep disturbances have been proven to contribute to fatigue in FM patients. Although non-restorative sleep and fatigue are the most commonly reported symptoms by FM patients, the exact cause of these problems is not well understood. A study reported that 50% of the women with obstructive sleep apnea syndrome or upper airway resistance syndrome had chronic pain and more than 11 tender points. One case report has suggested OSA as a possible cause for FM. No studies have been conducted to demonstrate the effect of CPAP treatment on symptoms of FM syndrome in patients with OSA.