I have seen that how you think in the day can influence how you sleep and the dreams that you dream. Sometimes just related impressions may create a very mixed-up dream and it has really no meaning. Other times I've seen my practice go into my dreams and actually help me get out of a potentially difficult nightmare by practicing in the dream, and noting the fear and turning my attention to a meditation object. Then the nightmare ceased to be a nightmare, in fact it was quite inspiring.
So I do believe that your practice can go into your dreams. The more you practice in the day, it will come into your dreams. Other times when the mind is very busy and there are of lots of impressions, it's helpful just to not take much notice of them. I do notice that when I have mixed up dreams, even in the dream I don't seem to take much notice of them. So perhaps that's also the practice, "Oh, this is a dream", even if I can't actually get out of the dream. Sometimes I've woken myself up from the dream and by saying, "Well, this can't be real, it's a dream."
If you happen to be full of dreams during meditation retreats, Mara doesn't have the ability to jump on you so much through the day so it will take the opportunity when you are asleep. That can happen, also. As well as having Dhamma dreams, you can also have Mara coming to try to test you in your sleep because Mara can't get past your armor of mindfulness during the day. It may also be that.
And as Steve always encourages everybody in the Compassion/Lovingkindness meditation, if you wake up from a disturbing dream, do a Compassion/Lovingkindness wish to yourself, to anybody in the dream and to people around the world who may be having bad dreams at that present moment.