For one its to late to take it back as you allready haven eaten the Zopiclone. You did't mention the dosage, may I ask how much as there is a big difference between a therapeutic and overdose.
Ime the GHB should be cleared from your systeem, very short acting drug, by now and you're just left with the Meth comedown. At a reasonable dosage there shouldn't be to much of a problem though maybe the Meth come down will overpower the Zopiclone?
When I was using a lot of GHB and Methylphenidate or MDMA. A benzo at the end of the party to sleep worked fine, I noted no negative interaction.
You can also use GHB to sleep instead of a benzo, but as the effects are so short I always woke up 1/2 way in the night and had to redose. Which quickly led to an addictive cycle, as in the morning this whole story starts again. GHB literally knocks you out at that doses unlike a benzo which feels a bit more like drifting of to sleep. And according to GF affected my breathing, creted some sort of Apneu. So taking an benzo after waiting a certain time frame, 6 hours in your case, actually improved how well I slept. Just my personal experience, not really harmreductive. But if you can keep it a once in a while thing its a good way to spend some good time.
