Dreamt of the Gayatri mantra

Had a bad dream a few days ago. Dreamt that I was in a shopping mall and someone handed to me a baby. Mysteriously, I came to realize that the baby is possessed by some malignant spirit. I began reciting the Gayatri mantra to exorcise the spirit as the baby writhes in pain in my arms. The Gayatri mantra did not seem to work well for exorcism purpose and I was contemplating to use the Lakshmi bija mantra or Durga bija mantra. Then suddenly I was awaked before I can change to another mantra. I read somewhere before that if one is able to recite a mantra in dreams, especially nightmares for protection, it means one has achieved some level of siddhi with the mantra. The imageries in the dream will also reveal the specific level of mantra siddhi one has reached. Hope this is true. The Tibetan Buddhist monks believe that dreams are creations and effects of our Karma.