A randomized placebo-controlled polysomnographic study of eszopiclone in Japanese patients with primary insomnia

ObjectivesTo evaluate the efficacy and dose–response effect of eszopiclone on sleep latency and sleep maintenance in Japanese patients with primary insomnia.MethodsIn this randomized, double-blind, five-way crossover study, 72 patients received placebo, eszopiclone 1 mg, 2 mg, and 3 mg, and zolpidem 10 mg in random order for two consecutive nights with a washout period between treatments. Objective sleep measures from polysomnography (PSG) and subjective patient reports were collected.ResultsAll active treatments produced significant improvement in objective and subjective sleep latency compared with placebo (P < 0.05 for all comparisons); linear dose–response relationships were observed for eszopiclone. PSG-determined wake time after sleep onset (WASO), sleep efficiency, and number of awakenings (NA), and patient-reported measures of WASO, NA, sleep quality, sleep depth, and daytime functioning significantly improved following treatment with eszopiclone 2 mg and 3 mg and zolpidem 10 mg versus placebo (P < 0.05). Eszopiclone at all doses increased total sleep time and stage 2 sleep time (P < 0.001 for both comparisons), but did not alter REM or slow-wave sleep. Eszopiclone was generally well tolerated; the most frequently reported adverse event was mild dysgeusia.ConclusionsIn Japanese patients with primary insomnia, eszopiclone 2 mg and 3 mg significantly improved PSG-determined and patient-reported sleep latency and sleep maintenance relative to placebo.