Effect of two antidepressant drugs on REM sleep and EMG activity during sleep

In a placebo-controlled study, the effects on sleep of single and repeated doses of imipramine and dexnafenodone, an antidepressant drug under development, were investigated in young, healthy volunteers. In contrast to placebo, both drugs suppressed REM sleep substantially after acute and repeated administration. As a consequence, REM sleep latencies increased under active treatment to mean values which were about two to four times larger than baseline values. Since the active inhibition of the muscle tone is a distinct feature of REM sleep, we studied the influence of the two antidepressant drugs on this variable. By means of computerised EMG analysis, tonic and transient EMG activity were computed for total recording time and for the different sleep stages. While tonic EMG activity during sleep was increased with both drugs, transient EMG events remained unaffected. Computerised analysis of the microstructure of sleep is an effective tool for studying the effect of antidepressant drugs on sleep.