Chlordiazepoxide-amitriptyline (Limbitrol) has been shown to be more rapidly effective than amitriptyline alone for treating depression. A double-blind, randomized study was designed to compare the effects of Limbitrol and amitriptyline on insomnia, anxiety, and depression. The rate of improvement of symptoms was faster with Limbitrol. No differences were noted between groups in the degree or rate of improvement of the sleep laboratory parameters nor in sleep Stages 1 to 4. Percentages of rapid eye movement (REM) sleep and REM latency were similarly affected by the drugs, but REM density showed a significantly greater decrease with Limbitrol. Phasic REM factors may be crucial in the role of REM sleep and depression.