EFFECTS OF CLOZAPINE ON SLEEP - A LONGITUDINAL-STUDY

Polysomnographic studies on the effects of clozapine, an atypical anti psychotic agent with strong sedative properties, on night sleep report inconsistent results. Most of these studies did not include baseline recordings and were not controlled for clozapine-induced fever, which is known to alter nocturnal sleep. We conducted a 2-week longitudinal polysomnographic investigation in 10 long-term drug-free schizophrenic patients prior to and at the end of the first and second weeks of clo zapine treatment. Rectal temperature was measured daily and patients w ith fever (> 37.9 degrees C) were excluded. Clozapine significantly im proved sleep continuity. In addition, non-rapid eye movement (NREM) sl eep and in particular stage 2 sleep increased significantly, while the amounts of stage 4 and slow-wave sleep decreased significantly. Cloza pine increased significantly REM density, but it did not affect the am ount of REM sleep. We conclude that in patients who do not experience clozapine-induced fever, clozapine has strong sleep consolidating effe cts resulting from an increase in stage 2 NREM sleep. (C) 1997 Society of Biological Psychiatry.