false awakening

I was in a house similar but not the same as the one I grew up in. My brother had been smoking pot (not in real life did he ever, to my knowledge) and I was angry with him for not sharing with me. Then I woke up in a car similar to but not the same as my real car; I was lying down feet toward the front. I wondered why I'd been sleeping in the car; the dream was vivid had I had a sense all this was reality. Slowly, the car started rolling backwards. Oh oh... it's going to crash into something, but for some reason I couldn't do anything about it. As the car continued rolling backwards, I realized it must be a dream and woke up. I should mention that I'd been taking Xanax for insomnia after prostate surgery for about two weeks and had been tapering off. Last night was my first night without it.