REM sleep suppression in cats by melatonin.

The pineal indole melatonin, injected into the third ventricle of unanesthetized cats, induced NREM sleep within 11-15 min and suppressed REM sleep for about 3 hr. A dose-related effect could be established between 1, 10 and 100 ng melatonin. The reappearance of REM sleep at about 3 hr following melatonin administration occurred with a marked rebound. The present results further support the hypothesis that melatonin represents the releasing hormone for pineal arginine vasotocin.