Everyone's brain chemistry is different isnt it, and we all react uniquely to some extent. If I take dhc + soma during the daytime, (i know soma is definitely a downer, but I find it stimulating when combined with DHC if i get the doses bang on - 90mg of DHC and 750mg of Soma is my sweet spot) ) i find it decidedly stimulating; typing big long posts and I get lots done and music sounds great. The same doses later in the day, or if I am tired, can just conk me out.
I have seen other people online describing DHC along the lines of 'stimmy'. It does energise some people.
I only take the combo very rarely, and its' effects are probably going to be very different for people that need the substances constantly for pain relief.
Mind you I can also find zopiclone paradoxically stimulating. If i can fight the sleep, at that moment it might have sent me to sleep, or if it just fails to send me to sleep, i can catch a proper happy stimmy buzz instead of being asleep. That might be a rarer reaction, but that will probably be what anyone who is into 'abusing' zopiclone will be doing.
(My brain chemistry probably would be "neuro-divergent" seeing as I've already been diagnosed with Autism and am going through the process for ADHD. You probably know that some ADHDers are known to find speed paradoxically calming, so we're probably not going to be neuro-typical in several ways when it comes to our reactions to drugs)