Dream Yoga is also known as lucid dreaming or astral projection, the etheric body can travel in dreams. There is every possibility of it leaving your body. When you remember it, it is remembered as a dream, but it is not a dream in the same sense as the dreams of the physical body. The etheric body can go out of you when you are asleep.
Astral projection is an out of body experience where an astral body is separated from the physical body. Astral body is recognized when an astral projection occurs. Astral projection is a happening where the astral body travels out of the physical body. Out of body experience or OOBE is the common name use for astral projection.