Microarchitectural findings in sleep EEG in depression: diagnostic implications.

A 10-year review of sleep electroencephalogram (EEG)-frequency analysis in depression reveals several consistent microarchitectural abnormalities. Decreased delta amplitude or incidence, particularly in the first 100 min of sleep, has been reported. Elevated fast-frequency EEG has been shown in both remitted and symptomatic depressed patients, especially in the right hemisphere. Further, interhemispheric coherence is reduced in both depressed groups. These microarchitectural features may not be present in narcolepsy, obsessive-compulsive disorders, or schizophrenia, despite similarities in sleep-stage characteristics. Collectively, these findings suggest that computer analysis of the sleep EEG may differentiate depressed patients from normal controls and from other clinical populations.