EEG and sleep
...Zopiclone causes similar alterations on EEG readings and sleep architecture as benzodiazepines and causes disturbances in sleep architecture on withdrawal as part of its rebound effect.[74][75] Zopiclone reduces both delta waves and the number of high-amplitude delta waves whilst increasing low-amplitude waves.[76] Zopiclone reduces the total amount of time spent in REM sleep as well as delaying its onset.[77][78] Cognitive behavioral therapy has been found to be superior to zopiclone in the treatment of insomnia and has been found to have lasting effects on sleep quality for at least a year after therapy.[79][80][81][82]