I didn't enjoy the euphoria either, as I felt more like a coked-up fiend than a focused, productive person. I gave it about a week before the insomnia became too much and ended up switching to XR.

I've experienced IR in the past (recreationally/nonprescribed, but at medical doses), and I do recall it causing issues with insomnia, though that may have been because I took it too late in the day. I didn't have any issues with XR, granted, when I take XR in the morning, I'm noticable lethargic 8 hours later and could easily sleep.

It really doesn't make a whole lot of sense, to be honest, because studies on the IR and XR show that the XR is exactly equivalent to 2x IR doses separated by 4 hours. Here's the chart to that if you're curious (page 12): https://www.accessdata.fda.gov/drugsatfda_docs/label/2013/021303s026lbl.pdf

Granted, it also doesn't make sense why certain major adderall generics have many people reporting that they are highly underdose/ineffective, yet, even my doctor said many people tell her that. I was under the impression these Pharmaceutical Companies must have very strict quality control to pass regulations for health and safety, but maybe we are simply giving them too much credit lol.