If one took many psychiatric drugs that interfered with sleep can one eventually return to normal sleep patterns immediatelyafter all drugs are gone?
Immediately? It's very hard to answer your question, because i don't know what drugs we're talking about, how long you've taken them, or what conditions you're dealing with. All these issues are important and could affect sleep quality. Also some medications are unsafe to stop suddenly, and must be tapered. I see Clonazepam on your medication list, and this one should definitely not be stopped suddenly.
Sleep. You should be able to return to normal sleep once the medications are out of your system. Ask your doctor how long each med takes to leave your system entirely. It may take you a short time to adjust to being medication free, if you are in psychotherapy it would make sense to talk to your therapist about your concerns and progress. Best wishes.