Comparison of the effects of zolpidem and flunitrazepam on sleep structure and daytime cognitive functions. A study of untreated unsomniacs.

The effects of zolpidem 10 mg, flunitrazepam 1 mg, and placebo, administrated at bedtime, were studied in 12 healthy male insomniac patients. The assessments included polygraphic sleep recordings during the night and a battery of cognitive tests (sign crossing test, dichotic listening test, digit span test, visual recognition test and free recall test during four times during the following day. Compared with placebo, both active drugs improved sleep parameters. However, with zolpidem, the results were not statistically different from placebo. Zolpidem dit not alter sleep architecture in contrast to flunitrazepam, which significantly increased stage 2 and decreased slow wave sleep and REM sleep. No significant interaction was found between time of day for the evaluation of cognitive function. Flunitrazepam significantly impaired attention and memory compared with zolpidem and placebo, while zolpidem did not differ from placebo. These results indicate that zolpidem 10 mg preserved sleep structure and daytime cognitive functions in contrast to flunitrazepam.