> Honestly surprised there isn't a religion that revolves around the belief that we are transported to an alternate reality/parallel universe when we dream.
Spiritism has that. When you sleep, your spirit separates from your body, and goes meet other spirits (some of them of other alive people, some of them of people between one life and the next; reincarnation is a central belief of Spiritism); the place where these spirits are could be considered an "alternate reality/parallel universe" of sorts. Dreams are mostly partial recollections of these experiences. For a longer and more detailed explanation, see https://www.febnet.org.br/portal/wp-content/uploads/2020/10/... starting at page 267.
Spiritism has that. When you sleep, your spirit separates from your body, and goes meet other spirits (some of them of other alive people, some of them of people between one life and the next; reincarnation is a central belief of Spiritism); the place where these spirits are could be considered an "alternate reality/parallel universe" of sorts. Dreams are mostly partial recollections of these experiences. For a longer and more detailed explanation, see https://www.febnet.org.br/portal/wp-content/uploads/2020/10/... starting at page 267.