Zopiclone, but not brotizolam, impairs memory storage during sleep

We compared the effect of a single bedtime dose of two short half-time hypnotics, brotizolam (0.25 mg) and zopiclone (7.5 mg), on memory storage during sleep in a double blind, placebo-controlled, three-way crossover design trial in eight healthy volunteers. Memory was evaluated using a standard word list free-recall test learned before the bedtime dose by the subjects, who were asked to remember the list the following morning. Digit Symbol Substitution Test revealed no residual sedation by brotizolam or zopiclone. Brotizolam did not affect the morning recall compared to placebo, but subjects remembered less words under zopiclone treatment, suggesting that this drug could affect memory storage during sleep.