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)-adrenoceptor agonist, and yohimbine, an alpha(2)-adrenoceptor antagonist, on nocturnal sleep in healthy men. Setting: McGuire Veteran Affairs Medical Center, Richmond, Virginia, USA, Subjects. Eight healthy male volunteers. Methods: Each subject slept in the sleep laboratory for 2 consecutive nights on three separate sessions, at 3-week intervals. On the 2nd night of each session, the subjects received yohimbine (5.4 mg), clonidine (0.1 mg), or placebo in a double-blind, randomized, placebo-controlled, crossover design. Results: There were no apparent effects of yohimbine. In contrast, clonidine completely suppressed rapid eye movement (REM) sleep in one subject and reduced REM sleep in the remaining seven subjects. Conclusion: Our study confirms that clonidine markedly decreases REM, even at a low single dose, and supports the hypothesis of the important role of alpha(2)-receptors in controlling REM sleep.