STUDY OBJECTIVE: To evaluate next-morning driving performance after middle-of-the-night use of zolpidem 3.5 mg in a buffered sublingual formulation (ZST). DESIGN: Single-center, four-period, randomized, double-blind, placebo-controlled, crossover study. SETTING: Maastricht University, The Netherlands. PARTICIPANTS: Forty healthy volunteers (20 females). INTERVENTIONS: Single dose of ZST administered in the middle of the night at 3 and 4 h before driving, zopiclone 7.5 mg at bedtime 9 h before driving, and placebo. MEASUREMENTS: Performance in a 100-km standardized highway driving test in normal traffic measuring standard deviation of lateral position (SDLP) - an index of weaving. Drug-placebo changes in SDLP > 2.5 cm were considered to refl...