@Lovecraft
Off the top of my head, I've read the "Innsmout" one, "the Ritual" (I think) and maybe one or two other short ones. Outside of the actual literature, I've read a lot about the overarching mythos of his universe. He has a big imagination. I don't want to sound like a snob. This was all probably 7+ years ago I was reading him. I felt that after reading a few of his stories, despite the seemingly infinite worlds, species and dimensions, I knew that the themese of his work were not seeming to go further from one story to another. Insanity, cosmic beings etc. I still think his work is amazing and he no doubt has had incredible influence on both horror and literature as a whole... anyway.
What you're describing is, I feel, the same idea I'm describing. No, you're not dependent. If we take a person with severe insomnia who is absolutely suffering. We give this person some Alprazolam. They go to sleep immediately, sleep through the night and awake feeling wonderful. The drug will have no chemical bearing on his body from the one usage. However, the experience of a means to end his suffering, to solve his problem just by swallowing a pill, this can do dangerous things to a man's mind if you follow me.
Taking the Alprazolam regardless of your tolerance is going to have an effect on your psychology. It will likely make it more difficult to fall asleep. However, like anything else, if you retrain yourself, put some time between you and the medication, you will forget and you will be essentially the same.
I hope this makes more sense. I feel like I'm rambling.