Well, if you embrace a spiritual view of things the serene sleep view possibly is closer to one's core existence and one short lifetime on Earth is not so much dreamlike but certainly absent the underlying truths for most people. Alternatively, various waking experiences can be revelatory, even in a spiritual sense, sometimes prompted by drugs but also by meditation etc.

I suspect the changed views all come from the same place, whether accessed by sleep, drugs, meditation, or whatever, simply because of their similarity. And what is this place?