EFFECTS OF BRETAZENIL VS ZOLPIDEM AND PLACEBO ON EXPERIMENTALLY-INDUCED SLEEP DISTURBANCE IN HEALTHY-VOLUNTEERS

The effects of bretazenil 0.25 and 0.5 mg, a partial agonist at the be nzodiazepine receptor on sleep electroencephalogram (EEG), subjective sleep quality and morning psychomotor performance were compared to zol pidem 10 mg and placebo using noise as an experimental sleep disturbin g factor in a single dose, double-blind, crossover study. Twelve healt hy volunteers were subjected to prerecorded traffic noise with a mean sound level of 52 dB(A) during eight hours in bed. Significant effects of noise were found on sleep electroencephalogram (EEG) parameters (r apid eye movement [REM] sleep, stage 2 sleep and number of arousals), and subjective sleep quality assessments, but not on psychomotor perfo rmance (choice reaction time, digit span memory, and symbol digit subs titution). Both drugs reduced the number of shifts between sleep stage s and the number of arousals and increased REM sleep latency. Only aft er 0.5 mg bretazenil, stage 2 sleep increased and REM sleep decreased. Both doses of bretazenil significantly affected performance in the sy mbol digit substitution test. Sleep quality improved under drug treatm ents compared to placebo. The results suggest that experimental sleep disturbance can be a valuable tool in the investigation of potential s leep promoting compounds.