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.
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