Sleep disorder associated with Fibromyalgia
Non-rapid eye movement (REM) sleep progresses through four stages that can be identified by electroencephalography. Quiet wakefulness with closed eyes is characterized by alpha-waves (8–13 Hz), whereas alert wakefulness with eyes open and bright lights is characterized by beta-waves (14–25 Hz). Non-REM stage I sleep is a transition from wakefulness and is associated with predominantly theta-wave activity (4–7 Hz). As deeper sleep is reached, the frequency of brain waves slows further, so that by non-REM stage IV sleep, delta-waves (<4 Hz) account for >50% of brain wave activity. It is delta-wave, or non-REM stage IV, sleep that is responsible for restful and restorative sleep.
The sleep disturbance associated with FM, termed alpha-delta sleep, is characterized by disruption of delta-wave sleep by frequent alpha-wave intrusion, such that non-REM stage IV sleep is significantly reduced. This sleep pattern is not specific for FM and may be present during periods of emotional stress, in chronic painful conditions such as rheumatoid arthritis (RA) and osteoarthritis, in sleep apnea syndrome, and in some otherwise normal individuals. Alpha-delta sleep is clinically associated with nonrestorative sleep.
Pearl: Sleep apnea should be considered in any patient with suspected FM. Patients (particularly males) may not be obese. All patients should be asked if they snore, have their neck size measured (risk increased if >17 inches in men, >16 inches women), and have an oral examination to see if the tongue obstructs the view of the posterior pharynx.
