Effect of clonidine on sleep patterns in man.

Clonidine (300 microgram orally) increased in man the total duration of sleep and strikingly reduced the duration of REM sleep. Yohimbine (10 mg per os) did not alter the sleep patterns in man but antagonized the effects of clonidine. These results provide evidence that an alpha sympathomimetic mechanism could suppress REM sleep and increased the total duration of sleep.