Combinations - Problems with Zopiclone and Methadone

[baron samedi]

SWIM has been taking Zopiclone most nights for well over a year now, as a replacement for his old sleeping aid of choice (cannabis). In January this year he went on a methadone maintenance programme, in order to kick his poppy pod addiction.
Up until this point SWIM was able to stick easily to 7.5mg Zopiclone at night (along with varying doses of Olanzapine). As well as pretty much always putting him to sleep and keeping him asleep, they also functioned very well in helping his night-time anxiety. Rather than putting him straight to sleep like it would most people, SWIM used to lie there for 2-3 hours, just enjoying the "buzz"/anxiolytic side-effects, enabling him to put a positive spin on whatever he was stressing or worrying about at the time. He knows that this is not how it is meant to be used but he liked it all the same. When he started doing poppies daily this side-effect seemed to be enhanced, reminding him of the buzz he used to get from combining opiates and cannabis at bed-time.
Things seemed to change however when he started his methadone treatment. He now finds it hard to get the same "buzz" from taking his Zopiclone at night, even though he has now doubled his dose to 15mg as a result. He was only on 30mg methadone for a couple of months, now increased to 45, but does not understand why changing from poppies to methadone would affect his zopiclone in this way. He knows that Zopiclone does lose efficacy over time anyway, but the effects he used to get from it seemed to change as soon as he switched to methadone. AnySWIY have an opinion on this. He also finds that if he has a meal some time soon before taking his zopiclone, its effects seem to diminish yet further, which has put him off eating any food in the evening at all.
Despite all this, he should state that they are still putting him to sleep and keeping him asleep, so he can't complain about this aspect. It just puzzles him why the mental effects of taking Zopi seem to have changed so much, even on double the dose he was on.