I’ve been reading on it for about 60 years.
If you immerse yourself in the accounts of these ‘encounters’, decades and even centuries! of them, many of them have a DEFINITE dreamlike quality.
I think most are probably closely related to dreams - another example of Vallee’s ‘control system’, which he has likened to a kind of ‘thermostat’.
And Carl Jung has said that dreams, even if we don’t understand them at all {I suspect even if we don’t recall them} are still doing their important ‘work’ inside of us.
I've read nearly everything Jung has ever written and his bios. Fascinating person.
I've got "The Red Book" on Kindle but haven't finished it. Recommend it to all Jung fans.
Mack and researchers (Garry Nolan of Stanford Medical most recently) studying the UFO phenomenon from the scientific angle have dismissed the idea that abduction accounts are hallucinations during hypnagogic or hypnopompic dream states, though there is a clear connection between them.
As an aside, after he died, Jung's friends admitted that he was deeply fascinated by the UFO subject but didn't want to publically discuss it because he thought it would detract from his work and legacy. He was probably correct about that.