Electroencephalographic sleep in secondary depression: a revisit.

EEG sleep studies are reported in 23 inpatients with secondary depression compared to a similar number of primary depressives matched for age and severity. No major patterns of EEG sleep abnormalities were found to differentiate between these closely matched samples at baseline or during amitriptyline treatment. Such results indicate that more severely ill secondary depressives manifest the characteristic EEG sleep abnormalities of depression. While these features had been reported previously to be specific for primary depression, earlier studies of psychobiological differences between primary and secondary subtypes may reflect an epiphenomenon of sample differences in age, severity, or percentage of patients with endogenous depression. Implications for further research and clinical practice are discussed.