Sleep in patients with chronic primary insomnia during long-term zolpidem administration and after its withdrawal

A double-blind trial was carried out to determine the effect of zolpidem or a placebo on sleep in two groups of insomniac patients with a diagnosis of moderate chronic primary insomnia. Zolpidem was given at a daily dose of 10 mg for 27 nights and was preceded (two nights) and followed (three nights) by a placebo. Zolpidem induced a significant increase of total sleep time, while total wake time and wake time after sleep onset were reduced. Values corresponding to stage 2 sleep were augmented, while stage 3 sleep and REM sleep showed no significant changes. Tolerance did not develop during the zolpidem administration period, and rebound insomnia did not show following abrupt interruption of drug administration. In addition, patients on zolpidem had a more peaceful sleep with no decrement of levels of alertness.