Having suffered from this before I can say this: sleep paralysis is absolutely terrifying. Whenever this occurs there is a small, rational part of your brain that tells you that nothing is wrong but this is drowned out by the absolute certainty that something or someone is just about get to you and you can't even move to defend yourself. It's a very primal fear unlike any other I've experienced and I find interesting is that it's a common theme across people who've also suffered from sleep paralysis.

I've experienced lucid dreaming as well and I can assuredly say that it is nothing like sleep paralysis. The physiological effects might be similar but there's a very big difference between consciously deciding to do something and waking up to a nightmare.

Unrelated, but interesting:

> That is to say there isn’t pain in the conventional sense; as CO2 goes up past critical levels, in the absence of fear or panic, the body will try breathing harder or faster and, eventually, you’ll pass out.

This is why most people drown. They panic and aspire water, long before they reach critical O2 levels and pass out.

It's possible to train and control the instinct to breath though. It's a great self-control exercise, and it's safe to try it outside the water. Try this:

Fill your lungs and hold your breath for as much as you can. You'll notice an irresistible urge to let go and breath (this is when most people panic, even though O2 levels are not anywhere critical yet). If you ignore your brain and keep holding, you'll notice involuntary movements in your diaphragm, forcing you to breath (this is when people drown). If you still keep holding, you'll notice the diaphragm movements get more intense, up to a point when it's impossible to keep holding your breath, but it takes a while still.

With enough practice, you learn to stay relaxed and post-pone those reactions as much as possible. After a while, you start being capable to hold the breath many times longer than expected. If you couple this technique with exercises for increased lung capacity and cardio (for lowering your base BPM), you'll be free-diving like a champion.

To expand on the uniqueness of the experience of suffocation: Suffocation is apparently the only experience that can produce fear in patients without an intact amygdala. In a recent study (http://www.nature.com/neuro/journal/v16/n3/full/nn.3323.html), researchers administered a mixture 35% CO2 and oxygen to three patients with bilateral amygdala damage and who could not recall experiencing fear in any decades for decades prior. All three had panic attacks. While it's thought that the amygdala contains CO2-sensitve chemoreceptors as this article states in the first paragraph, this behavioral result shows that other brain areas do too, and activation of these chemoreceptors is sufficient to produce fear even without the brain's "fear center."

I am reasonably sure that many of the people who believe they have been abducted by aliens (or seen them in their room with them) have probably just experienced sleep paralysis. I say this knowing that when I was younger I had a few episodes of it that still haunt me to this day.

I can remember at least one episode where I woke up into this state to a black tall figure essentially in my face.. giant eyes and the whole bit. I couldn't move and given that this was the first time sleep paralysis had happened to me, thought (and it truly felt) like the entire experience was real. If I remember correctly I broke out of the state by somehow getting my eyes to close in fear and then waking up what had to have been just a couple minutes later. Obviously there was no alien right in my face but it sure felt like it and bringing this story up now I can still 'feel' the experience all these years later. Odd how the brain works.

Edit: Ah, I'm not the only one who thinks most alien stories can be explained by this http://www.nytimes.com/1999/07/06/science/alien-abduction-sc...

Err... sleep paralysis can be bad if you don't realize that its an instant gateway into a lucid dream. I had lucid dreams long before I realized this, but at some point in my life during a sleep paralysis event i realised it was a dream, and after that i could fly, have sex, and be magic for as long as i remembered i was dreaming. Have fun the next time you have sleep paralysis, its not awful, its awesome.

Wow, there is a term for it! I get this all the time and didn't think enough of it to seek out understanding of it. It's it bit scary, but mostly annoying. If I'm sleeping I want to be sleeping, if I'm awake I want to be awake. Being somewhere in the middle isn't fun.

For me it's like a dream where I can see what I would be seeing if I were awake and I can make the decision to try to wake myself up, but moving is really difficult. In fact, I'm not sure that I'm actually moving myself at all or if I'm just dreaming that I am. So, I have to try to move my arms and shoulders, first very slowly and then I pick up momentum until I finally wake up. It's as if I'm trying to learn how to move again.

I never feel like there are demons in the room, but I do get a feeling of paranoia that someone could be messing with me and I couldn't do anything. Not really a rational thought since people could have been messing with me while I was totally asleep anyways.

I experienced sleep paralysis for several years before finding out that it was a phenomenon that happened to other people.

Less than 5% of those occurrences were hallucinogenic with extremely vivid hallucinations. Often the hallucinations involved a frightening but oddly archetypal witch hissing in my face.

Later, when I learned of the phenomenon I was both relieved (to know I wasn't alone) but also terrified that others who experienced this also saw witches.

I still don't understand the connection, and it's frightening still.

Curious if anyone else saw similar visions or otherwise had potent hallucinations accompany their paralysis. I have few other notable images; would be interesting to see if anyone else had similar ones.

I experience sleep paralysis often after starting study of lucid dreaming. For me, though, it is rarely the terrifying experience the OP describes. In fact, since it's such an easy situation to identify, I tend to become lucid immediately. Don't let this scare you if you're looking to start lucid dreaming.

There are also tricks you can use to escape. For me, scrunching my face and wiggling my toes always worked consistently.

I used to experience sleep paralysis on an on and off basis. Sessions were spaced enough that I wouldn't remember them for long. I thought it was due to high-level general anxiety.

There comes one session when I can't and don't want to go back to sleep. I wake up, turn on the computer and get on that old Deftones board. And there, there is a user writing about that topic and how he just experienced it and how he found out an article about it !

That article did a good job of demystifying the whole experience. It does not come from anxiety but can induce it (quite obvious). One interviewee reported he found the experience quite pleasurable, like being held in someone's arms. The article also stated that one you re-frame it in a pleasant way it wouldn't be a bad experience anymore: you could make it border on the erotic side of things.

And since then I have always been especially quiet and relaxed when having a sleep paralysis episode. YMMV.

Note: contrary to what I have seen in comments here you CAN´T force yourself to wake up from a dream.

which is how I decide to see it.

Oddly enough, the last film I worked on is about this. http://www.imdb.com/title/tt3033948/?ref_=fn_al_tt_3 if you're curious, but it probably won't come out until mid-2014 so it's in stealth mode as far as marketing materials go.

I hate when this happens and I have a stuffed up nose. The only thing I can control is my breathing and rolling, I can't even moan. So I breath in a noisy pattern to wake up my wife (I've told her that shaking me would 'wake up' my body), or roll onto the floor (ouch!) to regain muscle control.

I get sleep paralysis sometimes and have since I was like eleven, and honestly it isn't that big of a deal for me since it comes rarely. But as a kid? It's a religious experience, and not the good kind. If I'd known that this wad a thing, it probably would've been less terrifying.

Have had this experience periodically for most of my life, although more so during my teens and twenties (41 now, happens maybe 10 times per year).

Imagine waking up and not being able to move anything but the tip of your left pinky; furthermore, you're not in your bed but in some kind of nether twilight limbo that has nothing to do with time as we know it in waking life.

So, that's the starting point, basically awake in a coffin. Rarely I've been able to relax into the experience and fall back asleep, but more often it's been the herculean struggle to migrate the movement of that pinky to the hand, to the forearm, upper arm, and finally, somehow, roll over on my side and wake up.

As to its origins, not sure. Perhaps it's preparation for the final sleep, who knows; if so, still work to be done here ;-)

It's interesting the article mentions "being ridden by the witch" as a phrase from southern Americana folklore. It dates back a bit further than that, and is literally where we get the term "hagridden" from.

I had this for years and it comes back every now and then.

At first it was absolutely terrifying as I "heard" people walking next to my bed, "felt" my mattress being lifted, "seen" things floating around and other (now) pretty cool hallucinations. Now I'm able to get fully conscious during the process and realise what's going on, but I still have a hard time when I feel I'm suffocating :(

Just an advice, the trick is to focus your brain on your breath, don't panic and raise your awareness of everything that surrounds you. It will calm you down although you won't be able to move or call for help.

It happened to me a lot but fortunately I've discovered the 'trigger' that causes it for me. When I'm in bed I have to keep both arms above the duvet, if I don't there is a very high chance I will have sleep paralysis. I believe it's related to heat. If I get too warm it is triggered and keeping my arms above the duvet prevents this.

I've tested the theory quite a lot simply by trying to trigger sleep paralysis (I wanted to when I was experimenting with lucid dreaming) and simply covering my whole body (except my head) worked most of the time.

"Sleep paralysis is, crudely, your brain waking up before your body."

I experience this, or something very similar, every now and again, perhaps once every two months or so. I understand that I'm awake, I can hear, but can't move or even open my eyes. However, unlike what everyone else is reporting, I do not experience any fear, terror or have difficulty breathing.

In fact, I find it quite amusing. I typically try to fall back into sleep, which occasionally work, or try to stay in this state, but never managed to go beyond a minute or so...

Maybe it's not sleep paralysis then?...

I experienced sleep paralysis a long time ago in the form of too darker than black dog like creatures standing near my bed in my bedroom. They'd been hitting me with small bolts of electricity until I managed to overcome the paralysis then I just woke up in the same place.

I guess the condition and the visions had something to do with a therapy I was going through at that time.

I've found that attempting to roll your tongue while this occurs tends to lift the sleep paralysis. No idea why this works though.

So this is what it's called. I didn't even know it's a "thing". I'd say it feels uncomfortable, not terrifying. I usually just confirm that I can breathe, and once that fear is settled, I "haul" myself out of it.

I used to suffer from this pretty consistently for years until I researched it on the web and understood what it actually was. From then on it reduced to maybe once a year.

Funny how the mind works.

4 out of 10 people have it. I do too. It is the most terrible experience you can have. And it actually feels like a person riding your chest.

Given that I experienced sleep-paralysis just yesterday, it's opportune that I got to read this article now.

Thanks!

There are a lot of people who don't know what this is like; as someone who used to regularly experience this, I'd like to share some of my experience.

I have been in real situations that legitimately threatened my life and safety, and sleep paralysis consistently gave me comparable levels of stress and fear in each episode.

Imagine having a bad nightmare, so bad that you wake up from it. But when you wake up, your eyes are open and you cannot move. You see things that your mind logically knows cannot actually be there, but they are real for you. The REM dream state continues, overlapping reality.

In one case I woke up one my side to a large, dimly lit figure on the side of the bed, staring at me with red eyes. It just stared at me, while I physically felt something at the bottom of the bed dragging my body off. I couldn't move or even shift my head.

I was aware that I was awake, that this wasn't a dream anymore, but that this sort of paranormal situation should't be happening. I couldn't move, couldn't struggle - then the thing staring at me unhinged its jaws wider than should be humanly possible and screamed at me at the top of its lungs. It sounded like a human mixed with the shrill cry of a velociraptor from Jurassic Park.

I just remember trying to yell but not making noise, and feeling like I was drowning. I knew I was awake but the supernatural sense of wrongness was almost more terrifying than the hallucination.

Then, after what felt like minutes of struggling to breath, and the figure almost eating me, it all vanished, and I shook my body so violently I threw myself off the bed (seriously). I think I actually ran to the lights, turned them on and sat shuddering on my bed in the blanket for a while.

It's no joke. I used to regularly have these, and I sympathize with anyone who has had them. They're primarily caused by stress and anxiety (and have a high incidence in people with PTSD). It's not like a nightmare where you can convince yourself it wasn't real, because the things I hallucinated were as real to me as the lamp and nightstand.

Obviously I should say I didn't consume anything the night before. It's almost debilitating, and caused me insomnia for quite a while.

It was hard to describe to people - they are not the same things as night terrors. I would talk to people about it and they would say it was a bad nightmare. But it felt so real, it was like that scene from the Matrix with Neo and the bug.

Afterwards, details were always fully lucid and clear, and never became fuzzy. I eventually realized that the level of obsession I would get into when trying to get people to understand that it wasn't just a nightmare mirrored the hysterical reactions you would see from characters in Nightmare on Elm Street or the Exorcist. I never really believed in things like alien abduction, but I can fully understand why repeated exposure to sleep paralysis would cause someone to seriously question reality.

This exercise shouldn't be done underwater. This is an exercise for being aware of the diaphragm reflex, to go thru the sensations without panicking, which helps you to stay relaxed and develop a proper routine while diving.

By relaxing and exhaling you post-pone CO2 saturation as much as possible, but it still happens before O2 deprivation (it's only a problem when you reach <85% O2, and it takes a while for that).

Here's some great footage of a native from Philippines spearfishing the old way, showing a lot of self-control:

https://www.youtube.com/watch?v=YDspP4BhlTw

I agree and have thought the same thing. When I got sleep paralysis in my teens I had the terror feeling and had the feeling of a ghost in my room.

The only time I was able to relax during an episode, I had the experience of moving out of my body. If it is possible to think that with the brain in a state of sleep paralysis then it could be possible at other times too.

To add to my experiences, I've noted that it usually happens to me with these circumstances: 1) Sleeping on my back (it always happens this way, has never happened on my side or stomach) 2) poor bedding, where you've worn a divit/canoe into too soft bedding. 3) After having foods with lots of salt/msg (chemical imbalance? dehydration?) 4) On stuffy nights with stagnant, humid air or a stuffy nose 5) Sleeping on my back with arms above my head. I'm not sure why this is, but it's almost repeatable.

Ughh. Been there, done that. Thankfully I haven't experienced it since I was a young teenager. You are right about the whole thing being as real, or even more real than reality. It is almost a primal feeling of reality if you get what I mean.

I don't know about you, but for me even thinking about these episodes has me a bit on edge remembering them. Given that I think about 20 years have passed since the last time I had one, that just goes to show how significant they can be.

"It's almost debilitating, and caused me insomnia for quite a while."

That is the worst part of it. Insomnia causes more stress and anxiety which causes more episodes of sleep paralysis/night terrors etc. It is a vicious cycle.