Comparative efficacy of zolpidem and temazepam in transient insomnia

This study compared hypnotic effects of zolpidem 10 mg, temazepam 15 mg and in placebo in healthy adults. Two factors expected to promote insomnia, the 'first night effect' and a 2-hour phase advance, were combined in a single night laboratory-based double-blinded protocol. This was a multi-center study, with data collected in 13 sleep laboratories. Subjects with normal sleep histories and without prior sleep laboratory experience were randomly assigned to treatment groups. Medications were administered 15 min before lights out, with polysomnographic monitoring for 7.5 h. Subjective questionnaires and performance tests, digit symbol substitutions test (DSST) and symbol copying test (SCT), were administered at study entry and after arising. 630 subjects completed the study and provided data analyzed using repeated measures ANOVAs. Neither agent significantly reduced objective sleep latency relative to placebo. Zolpidem reduced awakenings and wake after sleep onset (WASO); temazepam did not. Both agents improved sleep efficiency and most subjective sleep measures relative to placebo, with zolpidem superior for five of six subjective outcome measures compared to temazepam. SCT, morning sleepiness and morning concentration were not altered by any treatment. Zolpidem significantly reduced morning DSST performance; temazepam did not. Zolpidem 10 mg provided greater subjective hypnotic efficacy than temazepam 15 mg in this model of transient insomnia, with reduced polysomnographic awakenings and WASO. Impairment of DSST was seen with zolpidem but not temazepam.