Apha-adrenergic receptor blockade increases human REM sleep.

1 An alpha-adrenergic receptor blocking agent, thymoxamine (150 mg i.v.) in the early night sleep of young adults increased REM sleep duration and also brief awakenings in the early night, while slow wave sleep, stage 3+4, was diminished. In the later night, however, stage 3+4 sleep was increased. Control experiments demonstrated that thymoxamine (i.v.) was without effect on blood pressure. 2 REM sleep duration may be inversely proportional to noradrenaline available at central alpha-adrenoceptors, but the control mechanisms for REM sleep appear interdependent with those for NREM sleep.