I'm reading now couple of books on the subject and have found things I had no idea about. I thought it might be worth posting them. But should it be here, i.e. in the folder under 'Buddhism'? That is an open question as the Dream Yoga has equal roots in Bön and in Nyingma strain of Tibetan Buddhism. Moreover, there is a claim by Bön followers that they are the original Buddhists as Buddha Shakyamuni wasn't the first Buddha. Bönpas claim that the first Buddha was Buddha Shenrab Miwoche 17,000 years before Buddha Shakyamuni. The first book I'm reading is actually written by Bön lama Tenzin Wangyal Rinpoche.
So if there is a feeling that this should go under 'Shamanism', feel free to move it!