Very interesting. I used to get night terrors as a child, they lasted well into my teens and young adult life although they waned a lot.
We have a book here called "Close Encounters of an Australian Kind" which is a comprehensive record as well as discussion on UFO sightings in the recorded history of Australia. A lot of the sightings were ascribed to being reported by someone who may have been on this edge of falling asleep, especially passengers/drivers in cars on lonely roads late at night. There are certain characteristics about these reports in terms of the appearance of unusual creatures or beings, seeming flattened somehow at times, which apparently gives some credibility to this theory. I've got to find the book again, it was very useful for my research in a number of ways. The incidence of this condition, and the reporting rate of UFOs, may be similar for a good reason.
A thought.
by the way, the book isn't saying that UFOs exist, or that they don't. It is simply finding some possible explanations for a number of reported sightings. At the back of the book is a list of sightings still unexplained at time of publication. I also found my own 'explanation for at least one of these, when a ratbag neighbour told me proudly he used to be a UFO hoaxer years ago and described some of his best 'tricks'. He had not read my book and didn't know about it at all. However, after his boasting I went home and looked up some of the dates and places he mentioned. I found one perfect match and a few likely matches. In a different life, this bloke would be a firebug.
Marg