A couple of nights ago I woke up to a man standing beside my bed with a knife against my throat. I was terrified, unable to move. He pressed the tip of the knife into the skin of my neck, just hard enough to compress the skin a bit, but it didn’t seem to break the skin. I could feel the knife clearly—it was cold and sharp. He gave me an evil smile and, for a moment, I was absolutely convinced I was going to die. And then suddenly I was able to move, and he was gone. I was alone in my bed, safe and sound. It wasn’t a dream—there was no sensation of waking up before the man disappeared.
It was scary, but, for me, not at all unusual. I suffer regularly from what is called Sleep Paralysis with Hypnogogic Hallucinations (SPHH). Generally with SPHH a person wakes up unable to move and with the sense of some kind of presence in the room with them. Often he/she will see a figure which seems to be the source of this fear. A common theme is for the figure to climb on the person’s chest and inhibit breathing. Then after a period of time which can be as little as a few seconds or as long as fifteen minutes the person will find him/herself able to move, and the figure and the fear will be gone. Many people will have this happen at least once in their lifetimes, and regular occurrences are more common than you might think. To be honest, my experiences tend to be a bit atypical, but there is remarkable similarity in the stories which are recounted by people from all over the world.
The best explanation that science can come up with is that it’s caused by an irregularity in the sleep cycle. Normally the brain paralyzes the body during REM sleep to prevent you from moving in response to your dreams and hurting yourself. Scientists theorize that in SPHH part of the brain wakes up while part is stuck in REM; you are paralyzed and still dreaming, but you are also awake. Thus far science has not come up with much of an explanation for why we all seem to be having the same or similar dreams when it happens.
The big problem inhibiting scientific research is that this is the sort of thing people don’t talk about. We live in a society which likes to be grounded in the rational and scientific. While there might be a perfectly rational and scientific explanation for SPHH, as an experience it does not fit within our normal perception of a rational reality. Because of this, many people will not talk about their experiences. To give you an idea how strong this compulsion to silence is: My sister and I shared a room growing up. We slept in the same bed for years. And only last month did I find out that she also suffers from SPHH. She had no idea what it was, but her hallucinations frequently involve spiders crawling on her chest. (My sister’s also arachnophobic, which makes me wonder if SPHH is like boggarts and tailors itself to an individual’s fears.)
It’s an interesting phenomenon—science being inhibited by science. For the record, I don’t generally believe that my SPHH is supernatural in nature (with one or two exceptions I won’t go into here), but it annoys me that it’s being dismissed, rather than studied because of social prejudices.
David Hufford who has studied the phenomenon can put it even better than I can.