An improvement in sleep with no rebound insomnia was observed during treatment for two weeks. Time awake after the onset of sleep was reduced after one week and increased after two weeks, whereas sleep latency remained reduced.

Zolpidem markedly increased the duration of Stage 2 sleep without affecting either slow wave sleep or REM sleep. Subjective evaluation of improvement in sleep was well correlated with sleep laboratory findings. Zolpidem did not impair the immediate memory or psychomotor performance of patients on the morning after its administration. Side-effects during the period of drug administration included drowsiness, fatigue, headache, anxiety and irritability. They were mild or moderate and wore off soon after awakening.