Objective: To characterize the patterns of alpha electroencephalographic sleep and their associations with pain and sleep in patients with fibromyalgia.
Methods: Pain and sleep symptoms of 40 female patients with fibromyalgia and 43 healthy control subjects were studied before and after overnight polysomnography. Blinded analyses of alpha activity in non-rapid eye movement (non-REM) sleep were performed using time domain, frequency domain, and visual analysis techniques.
Results: Three distinct patterns of alpha sleep activity were detected in fibromyalgia: phasic alpha (simultaneous with delta activity) in 50% of patients, tonic alpha (continuous throughout non-REM sleep) in 20% of patients, and low alpha activity in the remaining 30% of patients. Low alpha activity was exhibited by 83.7% of control subjects (P < 0.01). All fibromyalgia patients who displayed phasic alpha sleep, activity reported worsening of pain after sleep, compared with 58.3% of patients with low alpha activity (P < 0.01) and 25.0% of patients with tonic alpha activity (P < 0.01). Postsleep increase in the number of tender points occurred in 90.0% of patients with phasic alpha activity, 41.7% of patients with low alpha activity, and 25.0% of patients with tonic alpha activity (P < 0.01). Self ratings of poor sleep were reported by all patients with phasic alpha activity, 58.3% of patients with low alpha activity (P < 0.01), and 12.5% of patients with tonic alpha activity (P < 0.01). Patients with phasic alpha activity reported longer duration of pain than patients in other subgroups (P < 0.01). Additionally, patients with phasic alpha sleep activity exhibited less total sleep time than patients in other subgroups (P < 0.05), as well as lower sleep efficiency (P < 0.05) and less slow wave sleep (P < 0.05) than patients with a tonic alpha sleep pattern.
Conclusion: Alpha intrusion during sleep can be of different patterns. Phasic alpha sleep activity was the pattern that correlated better with clinical manifestations of fibromyalgia.