Sleep pattern alterations by naloxone. Partial prevention by haloperidol.

A continuous intravenous infusion of the opiate receptor antagonist naloxone, at doses ranging from 0.7 to 1.0 micrograms/kg/min (total dose 8.8-13.2 mg), was performed in eight normal subjects during the first 240 min of night sleep. A significant reduction in stage REM and in stage 4 percent duration was observed. Pretreatment with the dopamine receptor blocking agent haloperidol (2 mg intramuscularly before sleep onset) partially prevented the naloxone effect, suggesting that it is due, at least in part, to the stimulation of dopamine receptors.