Some of the changes in sleep architecture associated with major depression, such as increased REM density and poor sleep efficiency, return to normal with remission of depression (state variables); while others, such as decreased slow wave sleep and reduced delta sleep ratio, tend to persist (trait variables). Reduced REM latency has been reported to be both a trait and a state variable. This study demonstrates that psychotherapy can normalize sleep-associated state variables in a way similar to that of pharmacotherapy.
Researchers examined sleep profiles of 78 unmedicated patients with mild major depressive episodes and 44 normal subjects before and after six weeks of treatment with cognitive behavior therapy. As is true of patients treated with antidepressants, sleep efficiency, REM density, and REM latency normalized with recovery of depression. The triad of reduced REM latency, decreased delta sleep ratio, and decreased slow wave sleep tended not to change (it was possible to include REM latency as both a state and a trait variable without reducing the significance of the results). Changes from the ill to the well state were not dramatic because patients were not depressed enough to have distinct changes in physiology.
Comment: This study demonstrates that psychotherapy affects the neurobiology of major depression in the same way as antidepressants. Since slow wave sleep early in the evening is necessary for restorative functions, processing of emotionally charged memories, and maintaining neuropsychological performance, persistence of abnormalities may contribute to continued fatigue as well as faulty information processing and abnormal physiology, that predispose patients to depressive recurrences.
Published in Journal Watch Psychiatry April 1, 1998
Thase ME et al. Electroencephalographic sleep profiles before and after cognitive behavior therapy of depression. Arch Gen Psychiatry 1998 Feb 55 138-144.
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