Opioids Role of MOR in opioid-induced night terrors?

[Sleepdust]

Hi friends, this is my first post and it concerns something I've been curious about for years.

I take hydrocodone & oxycodone regularly and notice that I often have episodes of sleep paralysis and night terrors if I fall asleep within eight hours of my last dose. I do not suffer from these episodes without opioids. Hydrocodone is a MOR agonist with significantly less affinity for DOR. My question is, how would agonism of either MOR or DOR produce hallucinations? Maybe produce is the wrong word; more like, assist in producing (?)

Follow up question: I suffer from anxiety and depression but have not touched an antidepressant in years, since coming off paroxetine a few years ago. Interestingly, I never suffered from night terrors or dysphoria on opioid when on an SSRI. I think this is significant, and maybe the MOR agonism feels -different- when adrenergic and serotonergic neurotransmission is goofed up from depression/long-term anxiety *shrug*.

The night terrors are comparable to those I suffered after I finished a dextromethorphan binge a decade or so ago, taking more and more each day for a week, until I had the most terrifying and nightmarish "trip" on the last day that spurred bizarre and indescribable night-time hallucinations for about six months or so.

Thanks all, and let me know if I'm doing anything wrong in this post, since it is my first. Cheers!

 

[sekio]

I'd be blaming kappa opioid receptors if anything.

 

[Sleepdust]

"Hydrocodone in contrast showed strong and mu-selective binding." (entry concerns O-desmethyl-xx/family) (http://europepmc.org/abstract/med/2849950)

Which is why I'm confused as to why hydrocodone would cause me to have this reaction. I wonder if it's possible that the metabolites of hydrocodone have anything to do with it, since this only happens pretty long after my last dose - If I fall asleep on a big dose within the first two hours I sleep restfully with minimal intrusion of scary thoughts. Kind of like codeine -> morphine -> xx-phone/nor-xx? Bad metabolites towards the end of a session? I don't know.

Of note as well is that doses in the low range of supratherapeutic (12 - 15 mg) of hydrocodone cause dysphoria and anxiety for me, but therapeutic doses of 5 - 10 mg and opioid-tolerant doses of 15 - 25 mg cause neither, with the latter bringing on the euphoria and somnolence I want.

I saw that other people also have this reaction (the sleep paralysis), but it seems rare.