Effects of hypnotics on the sleep EEG of healthy young adults: new data and psychopharmacologic implications

Benzodiazepine hypnotics increase NREM sleep and alter its EEG by reducing delta (0.3-3 Hz) and increasing sigma (12-15 Hz) and beta (15-23 1-12) acti vity. We tested whether the nonbenzodiazepine hypnotic, zolpidem (10 mg), p roduced the same pattern of sleep and EEG changes as two "classical" benzod iazepines, triazolam (0.25 mg) and temazepam (30 mg). Sleep EEG of 16 subje cts was analyzed with period amplitude analysis for 3 nights during drug ad ministration or placebo. The effects of zolpidem were in the same direction but generally of smaller magnitude than those of the classical benzodiazep ines. These differences are more likely the result of non-equivalent dosage s than different pharmacologic actions. Period amplitude analysis showed th at the decreased delta activity resulted mainly from a decrease in wave amp litude. In contrast, the increased sigma and beta activity were produced by increased wave incidence. Delta suppression increased with repeated drug a dministration but sigma and beta stimulation did not. While these findings have little relevance for the clinical choice of hypnotics they may hold im portant implications for the brain mechanisms involved in hypnotic toleranc e and withdrawal delirium. (C) 2001 Elsevier Science Ltd. All rights reserv ed.