Lucid dreaming is the act of dreaming with you knowing about it, possibly with conscious control on them. Some even claim that with lucid dreaming is astral projection and astral travel.Theoretically, lucid dreaming is said to be a good cure for nightmares, as you have the knowledge that you are dreaming (albeit a bad one) and have control on what will happen.
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Lucid Dreaming - Lucid Dreams - Astral Travel And Projection Techniques