An experimental antidepressant increases REM sleep

1. An experimental antidepressant was studied through sleep laboratory recordings, psychoendocrinological tests and clinical measurements in terms of its efficacy, side effects and effects on sleep. 2. The design included a four-week drug administration period, preceeded and followed by a one week placebo period. 3. In the presence of antidepressant efficacy, the drug did not disturb sleep induction and maintainance. 4. The only effect on sleep stages was an increase of REM sleep during the short-term drug administration period which is contrary to the REM supressant effect of most antidepressants. 5. This finding suggests that REM supression and antidepressant efficacy are not necessarily related. 6. Further, given that the only known action of the drug is its inhibitory effect on GABAergic transmission, one can speculate that GABA mechanisms may be involved in REM sleep modulation.