Carter SG, et al. - Researchers investigated how high-dose zopiclone (15mg) could influence apnea-hypopnea index (AHI), arousal threshold, genioglossus muscle responsiveness as well as next-day alertness among selected individuals having obstructive sleep apnea (OSA) (low-moderate arousal thresholds without major overnight hypoxemia). According to their hypothesis, high-dose zopiclone would afford greater rises in arousal threshold and thus larger decreases in AHI but may come at the cost of raised hypoxemia and next-day impairment. This study involved 28 participants. A double-blind, randomized, cross-over design was used to assign participants to receive 15mg of zopiclone or placebo at each visit. Experts found that the AHI did not alter from placebo to zopiclone (-1.5events/h, 95% CI: -6.6, 3.5events/h). With zopiclone, no change was evident in arousal threshold, genioglossus muscle responsiveness and most other sleep parameters and measures of next-day sleepiness and alertness. It was concluded that no systematic decrease in the AHI nor increase in the arousal threshold was brought about by a single night of treatment with high-dose zopiclone in selected individuals with OSA.