Differential effects of chlorpromazine, imipramine, nitrazepam and amobarbital on REM sleep and REM density in man.

The effect of chlorpromazine (CPZ), imipramine (IMP), nitrazepam (NZP) and amobarbital sodium (AMOB) on the REM period of sleep (REMP) was investigated on four subjects by means of all-night sleep polygraphy with the schedule PPPDDDPP where P is placebo and D active drug. CPZ 25 mg resulted in a slight increase in %REMP, and no significant change in REM density (1 second fraction method) and total REM activity during the drug and withdrawal nights. IMP 25 mg produced moderate decrease in %REMP in the three drug nights, whereas REM density decreased only in the first drug night. NZP 5 mg resulted in a slight parallel suppression of %REMP, REM density and total REM activity during the drug nights. AMOB 200 mg produced a slight decrease in %REMP and marked decrease in REM density during the drug nights. Rebound increase of %REMP and a tendency of carry over decrease of REM density were observed in the withdrawal nights. Decrease in the REM density was more marked in AMOB than in NZP drug night. The importance of the simultaneous analysis of %REMP and REM density for the study of effects of psychotrophic drugs on sleep was emphasized.