This is a movie with interviews with people having sleeping disorders described as "Sleep paralysis", a subject studied but certainly not yet enough, or, perhaps, the knowledge is not substantial enough to very exactly what the therm, or condition, actually is.
Where is the line to be drawn between "regular" nightmares, which can be truly terrifying, realistic and actually ruin peoples lives, and more "direct" experiences of attacks connected with sleeping stages and different peoples mental states, caused by stress, traumatic experiences (known or unknown)?
Many opinions about this documentary, or what you prefer to label it, is "there's just a dude telling a dramatic story about seeing strange things when going to sleep, it's not real or scientific!" Well, take it for that then, and go in to this for what it is, in this case not a bunch of medical psychiatric professionals/professors stating what is actually possible or not, and not facts and proofs.
It is well made though, compared to many other "documentaries" dealing with things not easy to scientifically prove. The people interviewed seems to give a true statement, as good as they can, of their experiences, and it's not accompanied by any dramatic narrator trying to push a certain theory as "THE Fact".
It is actually quite scary hearing about these (real) peoples experiences, compared to plain fiction. I have friends who during stressful/painful episodes in their lives have experienced the very disturbing feeling of "dreaming while awake", so to speak, but that has always seemed purely connected to the fact that it is possible to have moments/lapses in rem-sleep, dreaming, and being completely awake. If you ask around, I'm sure many people can refer to some personal episode that's connected to this, and it is also how many medical professionals choose to describe it as. Several people I have talked with, having had complex heart surgery, for example, has had some of these kind of feelings afterwards. NOT, however, "beings" terrorizing them.
Then there is the point "what you feed the mind with is what it will circulate around", and I mean certainly there is a connection in these kinds of experiences, as well as other strange happenings, that if you open your mind up to certain influences, it can affect you. That does not take a doctor to understand. I don't put a judgment in these particular cases concerning that.
The scary parts in these stories is more related to actual strong perceptions of physical attacks from something, such as strong pain, voices, "beings" seemingly terrorizing/stalking them at night on such a regular basis. These experiences is not much commented by medical science (yet), because professionals studying it is very careful where to draw the line (not to ruin their careers, maybe...).
For example, a leading professor can state that "there is probably multiple universes", but the same one would be careful to say "there is likely beings from other dimensions that can hurt you while you sleep".
So, take it for what it is...
