The alpha-EEG anomaly is an abnormal sleep pattern observed in some people with fibromyalgia.
"Alpha" refers to alpha waves, which are brain waves that indicate you are awake but relaxed. When brain waves are recorded by an EEG (electroencephalograph), a sleeping brain typically displays delta waves during stage 3 sleep, which is considered "deep" sleep.
In the alpha-EEG anomaly, alpha waves intrude into deep sleep, suggesting that the brain is not resting like it should. Some researchers theorize that this anomaly may explain the unrefreshing sleep that is characteristic of fibromyalgia.