This is a question I have been wanting an answer so I am thankful for this thread.
I definitely agree that our dreams can be experiences in other realms or in spiritual and I would like to share about my views on it.
I have had many vivid dreams and my nightly adventures have always been either deep, scary, mystical/spiritual or strange or all the above at once, like really out there kind of dreams that make me question reality and leave me tired every morning as if I actually went somewhere.
In spirit we still have many of the sensations if not more senses then we would have in the physical. Whenever I have a very vivid dream, the sensation [essence] of that situation or being I had met with, can stay with me practically the whole day and even at random times over the week.
After describing my dreams to my mother she always tells me maybe I am going to other realms and dimensions and I feel it to be right.
In some dreams I am in as to what is referred as 'Night school' because it is a learning environment and I am not alone here. As an example, once I went to an initiation and sat down with these other beings who looked at my with surprise that I was there.
The mentor [ a tall male with long hair wearing robes] called me up and held my head where I saw a light swirling vortex [Don't know how to describe this] and it was overwhelming [perhaps Onenss or source energy].
In another dream, I was walking on a bridge which was connecting to other bridges that other people were walking and I heard 2 beings talk about me [invisible]
"she has reached higher self many times but she tends to fall to ego".
Many of these adventures take me to so many places and meeting different kinds of figures/beings. I feel a lot of the time I have tasks [quests] that I am doing with a team.
I grade them like so
1 - Dream travel [astral, spirit reality, adventuring, quests/tasks, meeting other beings and visiting other realms/worlds, aliens, elementals, etc]
2. Spirit [ educational environment/the learning sphere, spirit guides, gurus, deities, angels, co dreaming, collective, meeting spirit family/those who have passed, etc]
3. subconscious based [ symbols, reflecting thoughts/emotions/daily activity/feedback, animus/anima, shadow dreams, healing, aspects , higher self guidance, past life memories, etc]
So I would say yes, perhaps we are journeying the spiritual realms through our dreams, which is basically us traveling from our bodily states to our true spirit ones.
To me dreaming has become not much different from astral travel just minus the conscious effort of projecting via certain methods of leaving the bodily state and it focuses more on what
is more important on a spiritual basis because more is involved in a way of progress, healing, development of self, and obligations etc].
Also, what if these dreams are us connecting back to a larger aspect of us, like we have many other lives where we are accomplishing and experiencing different things in the spirit or other incarnations elsewhere? Just an interesting thought I wanted to share.