Neurophysiological factors in depression: new perspectives.

Within the last decade, the application of neurophysiological and neuroendocrine techniques has led directly to the identification of specific psychobiological correlates of depression. More recent efforts have attempted to establish linkages between mechanisms of action by antidepressants and such psychobiological factors. EEG sleep investigations, conducted with various antidepressants, have focused on the "specificity" of REM suppression or slow-wave sleep alterations. To date, results point to a greater commonality of action for REM suppression, lack of sedative effect as a necessary condition for clinical improvement, and the need for greater emphasis on slow-wave sleep research in relation to clinical recovery. The need for integrated theories of neurophysiological and neuroendocrine factors in depression is stressed.