Sleep paralysis - more common than you might think
In this week's Psychology Report, I talked with Associate Professor Dr Brian Sharpless of the American School of Professional Psychology at Argosy University, Northern Virginia, USA. Brian is interested in unusual disorders, and for this show, we are talking about sleep paralysis. Brian has been interested in the phenomenon of sleep paralysis for some time and we talked about the history and explanations of sleep paralysis, how common it is, and what can be done about it. I started with asking Brian how he became interested in this in the first place.
BS: Yeah, it kind of happened by chance. I mean, being a skeptic, if you look at the history of skeptics we often times look at a lot of interesting things. So, when I was a little kid I was really interested in some paranormal things and as I grew up and went to university, I start studying more. you know. Hard-edged science things. So, I studied anxiety disorders but I was always fascinated by trying to figure out why people believe strange things. So, when I was on post-doc it was in Philadelphia and it was on a panic disorder study. And so at the time a lot of people believed that sleep paralysis, which is what we'll be talking about today, really might be more, much more common in people have panic disorder and in people that are of African descent. So, being in West Philadelphia I had a lot of folks that had panic disorder and were also black. So, I worked up a measure and started trying to see how sleep paralysis manifested in people and how it also impacted on their lives - if at all. I guess, to jump back a bit, sleep paralysis is thought to be one of the naturalistic explanations for some strange beliefs, like beliefs that you might be visited by a demon, or that you might have seen a ghost, or that you might have even been abducted by aliens in your bedroom. So, I thought it was a nice way to merge my interest in psychology with some of my younger interests.
SJ: So, you explained a little bit there about what sleep paralysis is, which explanations come with sleep paralysis, so maybe we can just describe what people have told you their experience of sleep paralysis is like.
BS: Yeah, absolutely. Well, just I guess get down to a simple explanation, when you have sleep paralysis you either are going to sleep or you're waking up and you find yourself unable to move. So, it's not that it feels like it's hard to move but your body is actually paralysed. The only thing that you actually have some motor control over is your eyes, and you have partial control of your respiration, so it's a very scary experience if you're not expecting it. You're lying there on your back and all of a sudden you wake up and you have conscious awareness and you can look around the room but you can't move. So, the interesting thing is that REM sleep activity is still going on, which explains the paralysis. But, you also have dreams in about eighty to ninety percent of the cases. So, you're having dreams while you're awake which are essentially hallucinations because they're not there but they look just as vivid as anything else that your listeners are looking at right now. And what's even more interesting is whereas normal dreams are only scary around thirty percent of the time, sleep paralysis hallucinations are almost always scary and they usually involve seeing scary things. So, you might see human beings or non-human beings that are acting in threatening or malevolent ways. Back in the 1980s they started seeing sleep paralysis as potentially being a scientific way of understanding some of these more supernatural claims. So as far as going back to your original question about what people have told me, I've had people tell me they saw a ghost - one of the most common experiences is of seeing shadow people, which I hadn't actually heard of until I started doing research into this. So, shadow people are thought to be either time travellers or inter-dimensional beings that for whatever reason they can't quite fully manifest where we are, so all we can see are these kind of matte black shadows, shadowy outlines - they might be wearing hats, they might have red eyes and they’re sometimes malevolent, they’re sometimes neutral there's sometimes … they could they could just have as many motivations as any other person you meet. What's really fascinating is Stephen Hawking actually believes that they might actually be real. So, when I was doing my most recent study i started asking people what they actually saw, and a good chunk of them actually saw these shadow people. And then you've got all the classic ones - one of the scariest descriptions I ever had was a young woman who was around 21 who was paralysed and she woke up to a little vampire girl with blood coming out of her mouth, and this vampire girl was grabbing on her legs and screaming at her that she was going to drag her to hell. So, pretty scary stuff when you're waking up in the morning.
SJ: That sounds very scary and I'm wondering how many people listening to this are kind of nodding that to themselves now or recognising an experience that they've had. I know personally I think I've had one experience maybe about four or five years ago. It was a fairly benign experience but I did have the experience of my eyes waking up and me wanting to move my arm or my leg and it not responding to my conscious call to move my whole leg. And then me lying there trying to figure out what was going on, and because I'm a clinical psychologist I’d had some exposure to the idea of sleep paralysis and after a while of feeling quite scared and alarmed by this, and wondering whether I had a stroke, I figured, oh I think this is something else and I'm just going to sit here and wait it out and see what happens next. Actually I remember trying to keep my breathing under control and I'm thinking, you really don't need to be having a panic attack right now…
BS: Yeah, that makes a lot of intuitive sense - and see what you did what everybody does - you had a strange experience and use the categories that you knew to explain it. So, being a psychologist you were looking for a psychological explanation, possibly a medical explanation, and when people have it they use what's around them. So, if they don't have a good scientific understanding of sleep how complicated it is and how many things can go wrong, they could easily use other narratives. So, if you're a very religious person you saw something scary you might believe that you're being attacked by a demon or, if you were in Zanzibar you might believe that you're being attacked by this giant bat out of the jungle called the Popobawa who lands on your chest and does bad things to you. So, I think whenever we have weird things, we have to try to make sense of them - we can't not, as people, try to understand these things, but some explanations can be helpful and some can not be helpful.
SJ: You’re talking about their about the world view, the exposure of your previous experience, and how it is that you explain the world and how you use that to make sense of this experience. Culturally and I guess historically as well, what we know about how people explained these sorts of experiences in antiquity - you know really really quite far in the past? Do we know whether this was experienced in the past, through oral histories or otherwise?
BS: Absolutely. The earliest documented I could come come about that would meet the medical definition of sleep paralysis goes back to Ancient Rome, but it's been described much earlier. But given how they described it we couldn't exactly say that it met full criteria. But in the historical part of a book I just did on sleep paralysis I was able to identify 118 different terms going back from Ancient Greece to the present, and in dozens of countries for the experience. So, the core parts of it seem to be fairly invariant - so the paralysis, often times feeling a sense of pressure on your chest, difficulties breathing, and fear and seeing scary things - that seems fairly universal. I haven't actually found a culture that doesn't have something like that in their records. But each culture sort of puts their own spin on it so, again, if we were in medieval Europe we might see it as a visitation by an incubi or succubi - a very libidinal sex-crazed demon that's attacking you. If you were in Japan, you would call this Kanashibari, which means to be bound by strips of metal. In China, they call it being oppressed by the ghost. And if you were in Turkey you might call it the Karabasan and which I don't know if that's the correct pronunciation - I'm not fluent in Turkish - but it essentially means the dark presser. So, you have all these different names and in the earliest one I could find was Pan Ephialtes from Ancient Greece and this means Pan that leaps upon you; Ephialtes also I think is synonymous with tidal wave in in Greece as well. So, yeah, it seems like a fairly universal human phenomenon that because it's so provocative and so scary it's attracted attention from the lay public and medical professionals. In European cultures we actually used to call this The Nightmare. Our current idea of a nightmare being just a scary dream is really a 20th century invention. Before it had a much more specific meaning that was in line with sleep paralysis. So, in a classic nightmare, or nachtmahr, depending on your language, you would wake up be unable to move, feel pressure on your chest ,and feel a profound sense of fear - terror would be probably better. So, historically it seems to be very, very interesting and if you and if you know what to look for you can find lots of examples.
SJ: So there are some themes that sort of come out there - this wave of being taken over, this idea of feeling bound and trapped and these all seem to be quite common things that go across cultures and across time. How common is it in the modern day? When people talk about sleep paralysis, how many people at any one time in the population would be experiencing anything like this?
BS: I actually did a study on that. We aggregated data that I had with 35 other studies - so I had a sample of around 36,000 people and we had enough information to break it down by groups. What we found was about 8% of the general population, 28% of college-age students and 32% percent of psychiatric patients reported experiencing sleep paralysis at least once in their lives. That's just a one-off experience. Of the people that have had it -depending on the study look at - somewhere between 15 and 45% of those folks have it to such a degree that it actually causes a problem in their life, either because it happens so frequently that it disrupts their sleep or it is so upsetting to them that they might alter their lifestyle, or be so upset about it that it causes them problems. So, it's much more common than people probably thought. Back in the 80s, there was a lot of speculation it might actually be purely an African-American variant of panic disorder but the literature clearly indicates that it's not and even though in certain studies it does seem to occur in non-white populations the differences between it are really relatively minor.
SJ: I'm curious about that, particularly as you describe the difference between sort of the general population rate and then the college student rate. Is there a particular life-stage or age group that seemed to report more issues and experiences of sleep paralysis?
BS: Well, typically it seems to happen that adolescence is when you get your first episode, but why I think college students get it at such elevated rates and psychiatric patients is because you're really much more likely to have disrupted sleep. So, if you're a college student you're having classes at different times of day so you might have not be on a regular sleep cycle. If you’re a psychiatric patient you might be suffering from things like post-traumatic stress disorder or depression that are very well known to cause insomnia, to cause disrupted sleep, to cause unsatisfying sleep. And anything that disrupts your sleep is going to be a proximal cause of sleep paralysis. PTSD seems to go along with it pretty well, but if you do things like drink alcohol before bed, what happens is you might be able to get to sleep a little bit easier but you're not getting the right kind of sleep. Alcohol actually suppresses REM sleep so you get what's called REM rebound effects. So, you're more likely to have intense dream activity at the end of the night and that's more likely to make sleep paralysis happen. So, if any of your listeners do suffer from sleep paralysis, very simple things you can do are just not drink before bed, not use caffeine before bed, and not sleep on your back. If you sleep on your back, that is the position you're most likely to experience these episodes.
SJ: That's really interesting – these are the the sort of preventive measures just to reduce the risk of you getting this sleep paralysis episode in the first place.
BS: Yes, very simple things to do. And also to just kind of do what you did - try not to get upset, try to realise, oh I'm having sleep paralysis: I'm not actually … you know, that's not an extraterrestrial in my bedroom. I'm having a hallucination that's fairly normative and it'll pass and in probably between four and six minutes at the most.
SJ: Did you find any gender differences when you're looking at this dataset? Did see any differences between men and women?
BS: Women had it just a tiny bit more I think - I have to double-check the figures - but I think it was 3% more common and in women it was really negligible.
SJ: Right, and for those people who are getting repeated episodes in their lives does it continue for very long? Or does it spontaneously remit? How does it work out?
BS: It's quite an individual process. I mean, I worked with some people that had almost every single night, other people would have it sort of in chunks where they go through long periods without getting episodes and then all of a sudden they get more. So, the course seems fairly variable.
SJ: As you were talking I was sat there wondering, okay, so what if this person is in a relationship, for example, and they're sharing a bed with somebody else - how does that work? Do they tend to disclose their experience to their partners or do their partners become aware of it? And how does that impact upon their sleeping arrangements? Do we know anything about this?
BS: Not a lot, I mean I have some anecdotal cases of what people have told me, but in general, your partner would have to be paying very close attention to you to even though you're having it otherwise they think you're just sleeping. Some people have their eyes open, some people can't open their eyes and their eyes are moving around with their eyelids shut. There was a case of a physician in the early 1800s who actually would pay one of his servants to watch him as he was sleeping so that he could get out of it - and so he would tell the servant what to look for in the signs - his eyes darting around and pressured breathing and things like that. But the idea of of feeling strange about this is a big one and that's why I think shows like yours are important. I can't tell you the number of people that I've studied that when I start asking them interview questions about sleep paralysis they say to me, “Oh my God, you mean other people get this too?” So they think there's something either seriously wrong with them or this might be the beginning stages of them going crazy, because again, they're seeing the room just the same as they normally would, but they're seeing things in there that obviously aren't there. I had one woman who told me that she saw her room and there was this set of train tracks in them and she saw a train going through her bedroom. So obviously these things aren't based in reality, and there are also reports in the literature of people with sleep paralysis actually being misdiagnosed as having a psychotic disorder like schizophrenia and you can imagine how that could be possible because you have a strange experience, you see something that isn't there that you're very upset about and you tell your doctor who may or may not be familiar with the phenomenon of sleep paralysis. And you're in acute distress and the doctor is clearly able to see that you experienced something that wasn't real. I mean, if you reported train tracks in your bedroom; pretty improbable that you had that, so there are cases of that happening.
SJ: That's exactly where my mind was going in terms of the differential diagnosis of this issue as opposed to something else, such as a psychotic episode. You've talked very much about visual phenomena, people seeing things, becoming aware of shadow people, and this train tracks example. Can it show itself in other sensory ways, such as feeling or hearing?
BS: All the senses seem to be up for grabs, and sometimes you get that kind of uncanny sense that you're being watched - kind of like if you're in a big city walking around late at night, down a dark alley, you feel the sense that there are malevolent eyes on you. They call this in the literature, “the sensed presence” and what a researcher in Canada named Alan Cheyne found was there seems to be a sequence, such that when you wake up and you have a sleep paralysis, the first thing you might notice is this sensed presence and what we think happens is your mind tries to organise this, so you start sensing something and then you feel afraid in your mind and try to organise it into a visual or auditory modality. So, your brain’s trying to make sense of it - now you're seeing something and then finally if you're unlucky enough to have it go this far you might actually start feeling it. So, something might be on top of you pulling at your clothes, physically or sexually assaulting you, and there's a strong historical record going back even before we had any scientific understanding of sleep paralysis, that there's such a strong sexual component to some of these hallucinations. Especially in women, it seems to be much more common. And you can see how this fits into demonic attacks as well as alien abductions. A "classic" alien abduction will involve probing various orifices and a rape with instruments. So, it's very fascinating.
SJ: And you can imagine it's a very vulnerable position to be in when you do have this sort of conscious awareness or semi-conscious awareness yet you feel paralysed - you can just imagine how disturbing that can be for people.
BS: Yeah, and you talk to people and they are adamant it is not a dream and that makes it confusing, because they're trying to explain to people and they're like, “oh, you just had a bad dream,” they're like, “no, I was awake, I was able to think, I was able to process, I was able to see my alarm clock right next to me, and all this stuff was going on.” So, that creates a lot of shame and a lot of strange feelings and just finding out about it seems to engender relief in people. They feel, “okay, well this is a common event, I'm in fairly good company and its really not dangerous.”
SJ: Did you come across many individual differences, like personality, that seem to be correlated or associated with the frequency or commonality of sleep paralysis?
BS: As far as personality differences; not that much. Some of the early literature even even tried to split people into groups and give them MMPIs eyes and personality measures - they really didn't find anything of note. It seems that there is an association with belief in the paranormal. Now, this gets tricky because we don't know - is it a cause or consequence of having sleep paralysis? So, do you believe in paranormal things and then you're more likely to have sleep paralysis, or do you believe paranormal things because you've had sleep paralysis and have seen paranormal things? So, we don't know about that. Other things that seem to be associated with it are certain types of anxiety - so if you have high levels of anxiety sensitivity where you might be prone to misinterpret having an elevated heart rate for meaning you have a heart problem that's been a replicated finding in the literature - that if you have high levels of anxiety sensitivity you’re more likely to have sleep paralysis. If you have a history of trauma, whether it's full-blown post-traumatic stress disorder or not, you might be more likely to have it. If you have a higher body mass index, you might be more likely to have it and we think this might happen because if you have a lot of weight on your chest and you’re sleeping on your back you might be more likely to disrupt your sleep in the night and cause sleep paralysis. Those are some of the big ones that we've been able to identify so far.
SJ: Sure. So, if people find themselves in a situation where they are having these sleep paralysis episodes or they know people who perhaps are, what can be done about it? What are the effective treatments or interventions that that seem to work in this situation?
BS: One of the problems when you study weird disorders like I do, and I study a few of them, is that there's a perception that they're very rare and unusual so they don't get a lot of attention. So, there's actually no well-validated treatment for this yet. There are a number of promising things but there's not been one randomised control trial on sleep paralysis. I think a lot of folks still believe that it's fairly rare and that it doesn't really have clinical impact so we're starting to get a little bit of information about that - well it's actually not that rare and in about 15 to 45 percent of cases it actually does engender clinical consequences. So, there's some pharmacological options that seem promising and we're talking about some very small numbers of folks, like just individual case studies, or maybe three to five people but anything that suppresses REM sleep. So, the major antidepressants, the tricyclic antidepressants, the SSRIs; they seem to be effective because they sort of make REM sleep not really happen as much. As far as simple things people can do, like we talked about, not sleeping on your back, not drinking before bed, trying to reduce the general levels of stress in your life, and trying to get on a regular sleep schedule are very useful. I developed the first psychosocial treatment for this based on a cognitive behavioural model that I'm actually going to start piloting next month. So if you have any listeners in the Washington DC area that would potentially want to get some free treatment they contact me - I'm very easy to find online. I developed an approach to help people develop better sleep hygiene, and also to prevent episodes from happening, and when they do have episodes to try and get them out of it more quickly. And the way I developed it, I was trying to think, when you're developing a treatment for the first time it's very hard to know where to start so I started asking people in my sample of subjects who had it - and I ask them, “okay, well what do you do to prevent it and what do you do to try and disrupt it when it happens?” and they had a lot of good ideas and some of them, when we were aggregating the data, seem to be more effective than others. So, I started incorporating those things into the treatment. One of the things that seem to be useful was focusing on moving one little part of the body so maybe your finger or one of your toes or your tongue. A lot of the folks that reported sleep paralysis said that trying to do that as opposed to trying to move your whole body was more effective. Trying to calm down, trying to give yourself reassuring soft talk - like it sounds like you might have done when you had your episode - trying to relax seems to make the episodes last shorter periods of time. So, little things like that and it's a very quick treatment - it takes between 4-5 sessions to to get through.
SJ: It's interesting, isn't it, because I guess one of the things I'm thinking about as you're talking is that trying to establish that sense of agency even if it's just moving a small part of your body rather than the whole gross movement or that calming self-talk … and I'm thinking about the impact that may have on our experience of time as well. You know, that experience of self-talk helps time to pass in a very different way other than when you maybe are just kind of watching this thing happen, and it feels like it's taking forever.
BS: Absolutely - I agree with you 100%. I honestly don't know whether trying to move your finger actually does get you out of the episode sooner or whether it just serves to distract you from the scary things you're seeing and calm you down and make it less aversive. So, I have no idea and from a clinical perspective, I don't care. From a science perspective I care, and that's a very interesting question.
SJ: So, where next for you on this? Who should care about this research from your point of view? And what's the point of finding out more about sleep Paralysis? Where does this go?
BS: Even going back to the study I was talking about that demonstrated how common it was, I think that when you demonstrate that a phenomenon that was perceived to be rare and may be limited to certain groups of individuals, I think it's important when you find out that it's actually quite universal and I think it has a lot of potential implications. I mean, if we talk clinically we found that there is a not insignificant portion of folks who are actually troubled by this, troubled to the point that might they might not even feel comfortable disclosing it to their medical or psychological caregiver. So once there is awareness that something's come, and once there is awareness that it might actually be problematic, then you can start the hard work of trying to figure out, “okay, well how do we help these folks?” And I think more generally having providers know about it could help avoid misdiagnosis, like we talked about, either that they've got something more serious or potentially ruling out narcolepsy - we didn't talk about this yet but sleep paralysis is very common in narcolepsy which is much less common than having what's called isolated sleep paralysis which means sleep paralysis that isn't occurring in the context of a medical condition. I think just being able to know there's a name for something can help normalise it and reduce substantially frightening and shameful experience. And I think going back to the first thing we talked about, I think getting the word out is good for, I think, science literacy - because this could potentially help people realise that they're not actually being visited by fairies or extraterrestrials or demons, but they're having kind of a blip in a very complicated sleep cycle. So they are things I was thinking about a why we should care about isolate sleep paralysis. Probably to any of your listeners out there who have it, if it just happens once I would like to have you guys think about it as just an interesting story to tell your partner about, wake up and tell whoever sleeping next to you about it - I had this weird thing called sleep paralysis. But, if you are one of the groups that has it to the extent it's actually causing problems, what you should do is try and find somebody - either a psychologist or a psychiatrist or neurologist who specialises in sleep disorders, particularly parasomnias. So, that's the class of sleep disorders that sleep paralysis is in and there are certainly some things that could potentially help you out.