It seems something is definitely happening but, like Allan Hynek and others, I think these are extradimensional creatures instead of extraterrestrial.
In fact, as Whitley Streiber said...
"Increasingly I felt as if I were entering a struggle that might even be more than life and death. It might be a struggle for my soul, my essence, or whatever part of me might have reference to the eternal. There are worse things than death, I suspected... so far the word demon had never been spoken among the scientists and doctors who were working with me...Alone at night I worried about the legendary cunning of demons ...At the very least I was going stark, raving mad."
- Transformation, p. 44-45"I wondered if I might not be in the grip of demons, if they were not making me suffer for their own purposes, or simply for their enjoyment."
- Transformation, p. 172"I felt an absolutely indescribable sense of menace. It was hell on earth to be there [in the presence of the entities], and yet I couldn't move, couldn't cry out, couldn't get away. I'd lay as still as death, suffering inner agonies. Whatever was there seemed so monstrously ugly, so filthy and dark and sinister. Of course they were demons. They had to be. And they were here and I couldn't get away."
- Transformation, p. 181
Quality scientist Jacques Vallee, after long and extensive research, is convinced they are evil critters from a spiritual dimension.