WHICH DEPRESSIVE SYMPTOMS ARE RELATED TO WHICH SLEEP ELECTROENCEPHALOGRAPHIC VARIABLES

Sleep complaints and electroencephalographic (EEG) sleep abnormalities are associated with risk for new onset depression, illness severity, treatment outcome, and vulnerability for recurrence of depression. The aim of this study was to evaluate the strength of association between EEG sleep measures and depression symptoms, and to identify the varia bles that account for the majority of the association. Depression rati ngs from the Hamilton Rating Scale for Depression and the Beck Depress ion Inventory and polysomnographic measures were examined in 361 adult outpatients with major depressive disorder. Canonical correlation and serial multiple regression analyses were used to determine the associ ations between depressive symptoms and sleep measures. Canonical corre lation showed a unidimensional relationship between depressive symptom s and sleep measures (R = .55, p < .05). Fifteen depression items and nine sleep measures accounted for 95% of the correlation. Depression v ariables encompassed a core set of mood, neurovegetative, and cognitiv e symptoms. Sleep variables were primarily related to delta EEG activi ty, and this may be reflective of impaired sleep ''drive'' or heighten ed arousal during sleep. (C) 1997 Society of Biological Psychiatry.