EEG sleep and tricyclic blood levels: acute and chronic administration in depression

An understanding of the effects of antidepressants on sleep can be aided by determinations of tricyclic plasma levels in relationship to sleep. Previous studies have been established that steady state plasma levels of amitriptyline relate to certain aspects of rapid eye movement (REM) sleep. The present investigations attempt to replicate the REM sleep/tricyclic plasma level relationships in a larger group of psychiatric hospitalized patients for depression and to study whether such relationships persist in a group of ambulatory patients studied longitudinally for 1 to 2 years. In an acute treatment study of 38 patients, REM sleep percent and average REM activity demonstrated a significant relationship with plasma levels, even when controlled for age and severity. The sleep-plasma level relationships seem more prominent with amitriptyline levels than with nortriptyline plasma levels. In a long term comparison of plasma levels, tricyclic plasma levels showed a significant correlation with REM latency, REM percent and average REM activity. Thus, it appears that changes in REM sleep such as REM suppression correlate significantly with tricyclic plasma levels both on a short (4 weeks) and long term basis (1 to 2 years). The implications of these findings are discussed.