The alpha-EEG sleep anomaly was first described by researchers who used the term alpha-delta sleep to characterize a mixture of alpha and delta waves in a small group of psychiatric patients described as having generalized feelings of chronic somatic malaise and fatigue. Other researchers found that fibromyalgia patients had an excess of alpha-EEG not just in slow wave sleep, but in all NREM (non-rapid-eye-movement) sleep stages. Further, these same researchers discovered that the alpha-EEG sleep anomaly could be reproduced experimentally in healthy individuals by disrupting stage 4 NREM sleep. Alpha-EEG has been correlated to overnight increases in pain and decreases in energy; and the alpha-EEG anomaly may lead to more arousability during sleep, with resultant unrefreshed sleep.

It is well known that fibromyalgia is a chronic pain syndrome that is often associated with sleep disturbances characterized by subjective complaints of non-restorative sleep. Polysomnographic evidence shows abnormalities in the continuity of sleep: There is reduced sleep efficiency with an increased number of awakenings, reduced slow wave sleep, and the alpha-EEG anomaly in NREM sleep. And while fibromyalgia symptoms may relate to a non-restorative sleep disorder associated with such alpha-EEG anomalies, because the alpha-EEG anomaly is seen in healthy individuals when their sleep is disrupted, many experts do not wish to call this EEG finding specific for fibromyalgia, particularly because many fibromyalgia patients suffer primary sleep disorders such as sleep apnea or restless leg syndrome.