EFFECT OF CLONIDINE AND YOHIMBINE ON SLEEP IN HEALTHY-MEN - A DOUBLE-BLIND, RANDOMIZED, CONTROLLED TRIAL

Objective: To study the acute effect of clonidine, an alpha(2)-adrenoc eptor agonist, and yohimbine, an alpha(2)-adrenoceptor antagonist, on nocturnal sleep in healthy men. Setting: McGuire Veteran Affairs Medic al Center, Richmond, Virginia, USA, Subjects. Eight healthy male volun teers. Methods: Each subject slept in the sleep laboratory for 2 conse cutive nights on three separate sessions, at 3-week intervals. On the 2nd night of each session, the subjects received yohimbine (5.4 mg), c lonidine (0.1 mg), or placebo in a double-blind, randomized, placebo-c ontrolled, crossover design. Results: There were no apparent effects o f yohimbine. In contrast, clonidine completely suppressed rapid eye mo vement (REM) sleep in one subject and reduced REM sleep in the remaini ng seven subjects. Conclusion: Our study confirms that clonidine marke dly decreases REM, even at a low single dose, and supports the hypothe sis of the important role of alpha(2)-receptors in controlling REM sle ep.