Re: Erection Trouble
The drug use you mention could definitely cause hormone and mineral imbalance leading to things like impaired arousal. (And insomnia can be caused by the same mineral imbalance.) An occasional multivitamin might help (especially calcium, magnesium, and maybe zinc, iron, et al.).
Various infections and genital organ inflammations can also reduce the ability to become aroused. Cranberry juice can cure a simple UTI, but prostatitis, or other infection may require a anti-fungal or antibiotic regimen. So you'll want a health professional to check for that.
If a professional rules out anything pathological, you might look at food's effects. Personally I find chocolate a very effective arousal stimulant, and I know at least one other man who agrees, so maybe we're unusual or maybe there's something to that. (It does have that reputation popularly as well.) Cheap chocolate (Hershey's/Nestle) is garbage that encourages acne and all kinds of other health problems, good dark chocolate is the only kind worth eating if you're considering health.
I hope that helps!