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Tuesday, April 18, 2006

Ambient Somnambulism, or The Zombies Among Us

For those of you who haven't heard of this phenomenon, apparently the popular sleep aid Ambien (zoldipem tartrate) can have some very odd side effects: sleep walking and sleep eating. I think one of the networks did a profile on the phenomenon but I didn't catch it, so I dug around in the literature. Only a handful of articles deal with the subject. One of them in particular tweaked my interest, but more on that below...

Ambien is a sleep aid, a class of drugs known as hypnotics. For those pharma geeks, it is not actually classified as a benzo, but does have bind with high affinity at the ω1 binding sites on α-1 GABA-A subunits. Typically prescribed for the treatment of insomnia, it has a short half-life of 2-3 hours. Thus, a crucial part of the dosing regimen is to take the drug only when you know you are going to get at least 8 hours of sleep. Apparently, those who are forced to wake up earlier experience some interesting side effects, as can those who take the drug with alcohol.

Sleepwalking and sleep-eating: A small subset of Ambien users will sleepwalk and even sleepdrive when they use the drug. The scant literature on the subject suggests that those who were sleepwalkers in childhood, or those who have had brain injuries, are more likely to experience this set of side effects.

Memory loss also occurs, and anecdotal reports suggest that some Ambien users have actually raided the fridge while somnambulating and put on a substantial amount of weight, with no recollection of doing so. Others have apparently found themselves in car wrecks or pulled over by the police, with no recollection as to how they got there (although I personally find this a little too convenient).

I find this phenomenon intriguing for two reasons. One is zombies. No, not the Romero flesh-eating sort. In philosophical circles, much discussion occurs over zombies-- specifically, whether the existence of an entity that looks, acts, and responds normally but with no consciousness is possible. Can there be a human who goes to work, has a wife, coaches little league, but has no conscious experience? Perhaps here we have a way to investigate the possibility. Does Ambien shut off excitatory (or activate inhibitory) neural circuits that directly disengage a "consciousness" module or diffuse neural net? Can a somnambulant Ambien user "learn" new things, be they cognitive or motor skills, and can these new skills be performed/recalled at a high skill level when fully conscious, despite a lack of mnemonic recall for the event itself? Or can he/she be made to become fully conscious while in this state e.g. through the use of pain or loud noise, or direct stimulation of other neural circuits? To what extent does Ambien actually interfere with conscious perception? Do Ambien users display their normal personality when they are having a somnambulatory event? Can we stick them in an MRI or EEG and observe how activation patterns differ when the person is conscious and when they are on Ambien? David Chalmers is likely wetting himself at the experimental possibilities, while Daniel Dennett won't be particularly thrilled.

The other reason I find this intriguing has to do with memory. Perhaps the individual is fully conscious, but simply doesn't remember what happened once the meds are out of his or her system, simply because Ambien mucks up memories. Certainly there have been reports of memory impairments in patients who took Ambien but didn't get their full 8 hours of sleep. We may have an interesting drug with which to study the neural mechanisms behind the encoding and retrieval of memories. Certainly there has been quite a bit of research into the memory-altering effects of benzodiazepines and GABA-ergic compounds.

As I mentioned at the start of this post, one paper in the lit search struck me as particularly interesting, because it suggests that certain combinations of drugs may be used to elicit the somnambulist effect, and while one drug (zolpidem, in this case) may not elicit somnambulism, the system could be primed for the effect upon introduction of the second drug (valproic acid, in this case). While this may not hold true for all patients (particularly at one dosing regimen), common mechanisms may be elucidated in this manner. Conceivably we could build an inductive explanation to these phenomena.


  • I am responding to your post, but I have no memory of reading it. Yet I feel compelled....

    Seriously, though: Is there any indication that ambien interrupts theta waves? Perhaps it prevents ltp? or fools with the modulation of serotonin?

    I'm not a psychopharmo guy. Sorry.

    By Blogger Dan Dright, at 4/18/2006 10:25:00 PM  

  • Me either. :)

    Probably all of the above, although I'm not familiar with the distribution of GABA and benzo receptors that it activates.

    By Blogger Evil Monkey, at 4/18/2006 11:23:00 PM  

  • Olanzapine is another one that can cause sleep-related eating disorder.

    By Blogger Sandra, at 4/19/2006 08:06:00 AM  

  • I don't pretend to understand all of the scientific details you mentioned. However, I think that the possibility of determining whether it is possible for a person to act like a "zombie" while sleeping is very exciting. Answering this question could have very important consequences. For example, there have been several court cases in which a person murdered people (often his or her own family) and then used the defense that they were sleepwalking at the time and did not remember the event. From what I gather, there were scientific experts on both sides who gave their opinions, but there were precious few facts to back them up simply because not much is known on the subject.

    By Blogger epigirl, at 4/19/2006 09:06:00 AM  

  • I'm having a hard time understanding what it means for a person to be a zombie. If a person is, to use one of your examples, coaching a ball game, then how could the person not be conscious? He's taking in input through his senses, processing it, and using it to perform as a coach. In that kind of situation, what would it even mean to say he was not conscious? If all you've got to go on is the fact that he later doesn't remember coaching that day, then isn't that just amnesia?

    By Anonymous Anonymous, at 4/22/2006 06:20:00 PM  

  • Consciousness in the philosophical sense takes on different connotations than just "awareness". Decent introductory books on the subject have been written by Damasio, or perhaps Churchland.

    Think of it this way; you do all sorts of things without necessarily being aware of them. You can drive a car while having a conversation and not even pay attention to the road (of course if something unplanned happens you'll be at a detriment, but you get the idea), or even be conscious of the individual motor plans for "start" "stop" "turn right" etc.

    Alternatively, think of it like a computer; computers can perform all sorts of functions without having any sort of awareness (of course, this is debatable and part of the "hard" problem of consciousness). These issues are explored pretty thoroughly in David Chalmers's book The Conscious Mind.

    By Blogger Evil Monkey, at 4/22/2006 10:30:00 PM  

  • Isn't Chalmers' concept of the zombie, though, supposed to trouble the idea that consciousness can be explained by physical phenomena? I can't even remember if I've read Chalmers' original description or just a lot of secondary sources, so I might be getting this wrong. But I thought that the zombie was supposed to be physically identical to a human but non-conscious... so Chalmers wouldn't want to know that MRI or EEG data differed, although I'm sure he could explain it away. (I talked about this post on my blog, so feel free to go tell me I'm off the mark.)

    I suspect it'll turn out to be memory rather than consciousness, but the connection between Ambien users and philosophical zombies is really brilliant.

    By Blogger jess, at 4/24/2006 12:03:00 AM  

  • I suspect you're right about memory. And you're spot-on regarding Chalmers but I bet he'd be excited regardless.

    By Blogger Evil Monkey, at 5/03/2006 12:06:00 AM  

  • There is an important distinction to be made between the "sleep walking" that is attributable to drug-induced amnesia, and the more interesting phenomenon of somnambulism. The latter is a form of REM-disordered behavior, and as such has more serious moral and legal implications. During REM-phase sleep, vivid dreams may occur that fully engage our emotional faculties, but bear only a tenuous relationship to our waking life. Normally, we are protected from disaster by a physiologic paralysis that prevents our getting up and acting out our dreams. When this fails, however, the dreamer may get up and perform complex activities while still being unresponsive to external stimuli and otherwise still asleep. The significance of this is that anything is possible in a dream, including behavior that would never be considered during waking consciousness. So the question is, in this state, is it possible to, e.g., murder loved ones and not be a moral agent responsible for one's actions?

    By Anonymous Anonymous, at 5/10/2006 10:36:00 AM  

  • Unfortunately there is no clear answer to the moral conundrum. The better strategy might be how to identify those who could legitimately employ somnambulism as a defense, and parse them from those who would abuse that status.

    As for the line between somnambulism and drug-induced amnesia, I don't think it is that easily defined. Ambien clearly induces its effects more frequently in people that were documented sleepwalkers, and it does appear that abnormal behaviors might be induced by the drug; gaining 100 lbs due to raiding the fridge is not something most people would follow through on, even if they considered it during the course of the day. Ambien may dis-inhibit certain actions in some people.

    By Blogger Evil Monkey, at 5/10/2006 02:47:00 PM  

  • Isn't it true, though, that somnambulism is not always associated with a lack of memory? I frequently (once every couple of months) murder my bedside drawers, pulling stuff out, contructing little structures out of the lamp and other things. When I wake up in the morning I'm suprirse by what I've done, but I do retain a vague dream-memory of what I was doing. I don't remember why I did it, but I do - vaguely - remember doing it, and having had a reason at teh time.

    So I think of sleepwalkers as conscious in the same way we are conscious during a dream: that is, a different person altogether, perhaps confused and with unusual motivations, but still able to respond to stimuli.

    By Anonymous Anonymous, at 6/01/2006 08:53:00 PM  

  • I just found this, and wanted to thank you for the post. It's helping us gather information in preparation for a doctor visit today.

    My husband has had several episodes of sleep-eating with NO memory, dreamlike or otherwise (he in fact argued vehemently with me when I first informed him he was doing this) of his actions afterward. He leaves behind a HUGE mess, though, so the evidence is there.

    He stopped taking Ambien as of night before last, when he nearly burned the house down by putting an assortment of frozen foods in the oven, turning it on high, and going back to bed. Fortunately I awoke to the smell of smoke (I like to think that the smoke alarm was just ABOUT to go off), and averted disaster.

    Oh, and thanks for the link to that case report, too. Wanna guess what other medication my husband is on? 4,000 mg. Depakote daily.

    By Blogger ninjapoodles, at 12/15/2006 08:59:00 AM  

  • i think this si probobly the gayest thing in the yeah i KNOW this is the gayest thiong in the world

    thankx alot ass munch for wasting 5 mintutes of my dick

    By Anonymous Anonymous, at 3/22/2007 07:29:00 PM  

  • As Jess points out, Chalmers takes the zombie hypothesis "all the way" as part of the intellectual exercise that props up his property dualism. I.e., that we could imagine a hypothetical creature that is exactly identical to a normal human, say Chalmers himself, and behaves exactly identical, with emotions and poetry and music and brilliant insights and love and hate and child rearing and social belonging and elation and depression and homicide etc. etc.. The full range of human experience -- just no "light of consciousness", no "quasi-theater". But the evidence regarding absence seizures, blindsight, driving while talking on the cell phone, sleepwalking, and now Ambien-walking says (to me, anyway) that Chalmers needs to get real, because some empirical data is accumulating which indicates that we might -- possibly -- still uncertain, but maybe -- we might be starting to narrow down the location and processes involved at the foggy border between consciousness and non-consciousness.

    IIRC, Edelman thinks that Phase 4 sleep is pretty close to being dead, relative to our higher levels of mentality anyway (the body processes at Phase 4 are still far from death, of course). The thalamus and cortex just ain't looping at that point; the maps are mostly on their own, in stand-by mode. Then the absence seizure starts, or the sleepwalking starts, or the Ambien-walking starts. Some loops do get going, enough to bind the motor control areas, sensory perception areas, and proprioception. The subject can now drive a car or raid the fridge and chow down. I know, we're not sure that there is not some consciousness at this point. Wake the sleepwalker up, and they [usually] have no memory of what they were doing, even though it was but a second or two ago. Maybe it's just a memory problem; the episodic/phenomenal short-term memory areas just didn't plug in to the loops. (There was obviously short-term procedural / motor memory; those devices obviously plugged-in). And yet, isn't it arguable (but admittedly, not at all certain) that the short-term episodic memory device is a sine qua non for what Damasio described as "core consciousness", which has no long-term time sense, but still needs short-term temporality to click? Even if it is all "multiple drafts", doesn't something bind / confabulate the "draft components" into a "quasi-picture" on the Cartesian "quasi-screen" (or perhaps Baars' "working stage")? And isn't that "time/event smoothing" device behind phenomenal consciousness just not working in the sleepwalker?

    I know, the whole thing is extremely complex, and it may be too good to be true. Perhaps we haven't corralled the whole thing here; perhaps we can't say that "whatever is the difference between consciousness and non-consciousness happens right in that little state-transition space; so let's get on with digging up the neural correlates and such from that space, and see what we shall see".

    OK, I'm not a neuroscientist or a psychologist or a trained philosopher. Just a layman interested in the subject, have read a few of the popular works of Damasio and Edelman and Rama, plus some of the philosophers and shrinks. I'm still learning. If I'm totally off the wall here, then any corrections will contribute to my learning process. Thanks much, Monkey Man (with all due apologies to the Stones -- oh, am I showing my age here?).

    By Anonymous Anonymous, at 4/17/2007 09:18:00 AM  

  • My name is Catherine Snow and i would like to show you my personal experience with Ambien.

    I have taken for 1 years. I am 57 years old. Works great if I take it on an empty stomach, and get right into bed. If you take it and try to keep yourself awake, you can override the pill and be up all night.

    Side Effects :

    I hope this information will be useful to others,
    Catherine Snow

    By Anonymous Anonymous, at 9/26/2008 03:37:00 AM  

  • I too am a current Ambien user. I have had some very interesting events occur while I was on it. It is not every time I take it, but I have been known to type on the computer to my husband (with lots of type-o's, which is not like me), talk in slurred speech about odd things (ie: pirates or other people in the room) sounds crazy I know. Last night I was having issues with a sinus infection and I had gone to bed only to discover when I awoke the next morning, I had apparently taken a few of the other medications I had in the medicine cabinet for my sinus infection. It was a scary thing to not be able to recall doing this, not to mention the potential HARM I could have unknowingly done to myself by doing so. (FYI... yes, I suffered a severe closed head trauma in '93). Is there anything that can make the odds of this occuring again less likely? Also, just how common is this sort of thing? I don't want to stop taking the meds because I cannot sleep worth a toot without it, but I do not want to risk doing anything else that I may not recall either. What do you suggest?

    By Anonymous Anonymous, at 12/05/2008 12:29:00 PM  

  • I am a 57 year old woman that WAS taking Ambien and began to notice that some "curious" things were happening in the middle of the night after taking it. I started eating and cooking with no recollection of doing either the next morning. Initially my husband and I didn't think that much of it because although I didn't remember we sort of laughed it off. Now I realize that there was absolutely nothing funny about it. Since I was only taking Ambien 3 or 4 times a month I wasn't making any connections to what was going on. However, (and this is when it got real weird and scary) one day I went out to my garage and my car's windows were all down and the sunroof was open. I am a freak about my car and even when it's safe and secure in our garage I always keep my car locked AND since I bought the car I have never opened up the back windows yet ALL of the windows were opened and all of the doors were unlocked. Initially I blamed my husband and he swore he had not used my car. Then I started thinking someone had somehow broken into my car but there was nothing missing or any evidence whatsoever that anyone had been tampering with my car. And it's a BMW so it's virtually impossible to get into that car without a key or FOB. I also started getting this warning light on coming on telling me that my battery was really low. I couldn't understand why my battery was low because it was only 2 years old. I even took it to BMW and fortunately it's still under warranty so they charged it up for me but then it happened again (the warning light). Then a few weeks later I took a terrible fall and initially my husband and I thought I had fallen out of bed (which to my knowledge has never happened before) and it was very worrisome because I awakened in extreme pain and was right next to my bed so that's what we thought at first. However, when we started thinking it through and tried to reenact the whole thing we realized that it would be physically impossible for me to have fallen out of the bed and have this injury under my arm by falling out of the bed. It would be impossible because if I had actually fallen out of my bed and hit my nightstand it would have been my head that would have hit the nightstand and no way under my right arm. We now are virtually certain that I had been sleepwalking and was trying to get back into my bed and missed!!!! The next thing I knew I screamed out loud from the pain and my husband woke up to see my lying on the floor next to my bed. I was in incredible pain and had a nasty bruise and thought the next day I had broken some ribs.....long story short I started Googling sleepwalking and BINGO I was blown away when I saw how sleeping and Ambien were intermingled. If you google sleepwalking you are almost certain to come across something about Ambien. If you Google sleepwalking and Ambien there are hundreds of articles. From that day forward (a month ago) I stopped taking Ambien completely. Today I saw my doctor and I started to tell him that I had something pretty serious to talk to him about and I began telling him about me cooking and eating and actually getting in my car and remembering none of this and the first thing he said was "No more Ambien for you." And so, I feel like I am one of the lucky ones because I've read some horror stories about people sleep driving, becoming violent and even killing people they love while sleepwalking on Ambien. There are 26 million people in the U.S. alone that take Ambien so I have no idea how many people may have the effect I had but I am 100% sure it was the Ambien because I never slept walked before I started taking that stuff and to my knowledge haven't slept walked since I stopped taking it. And there's been no evidence of any cooking, raiding the fridge or signs of me being in my car. When I think all of this is just totally creeps me out. We have a 2 story home and I could have fallen down the stairs, burned our house down, gotten in my car and actually driven somewhere and I could personally could have died or killed someone else God forbid if I did drive and I have read that plenty of people have driven. They end up either dead or waking up in a hospital or even jail with no recollection of how they got there. I've also read that some people get violent and do some pretty crazy things so I am happy that at least I was fortunate enough to pretty much diagnose the problem on my own. I have a degree in Health Sciences and so I'm pretty big on doing research. It is terrifying to think of what the human mind is capable of doing and feeling like I was a zombie for awhile unknowingly. I would love to know just how many times I did sleepwalk and if I ever tried to start my car or did I just sit in it??? I do know that it was in the 20's the night that I was sitting in my car in the freezing garage with all my windows down and sunroof open. I just read something online yesterday about a man in Wisconsin that died earlier this month because he was outside sleepwalking while on Ambien and it was 20 degrees below Zero and he was barefooted and he ended up dead. That's just one more weird thing about it all. If one can not sense hot or cold (like me in a nightshirt only in my car while it was in the low 20's) why is it that you would eat??? I would think it would affect your sense of taste since it affects your sense of touch. I don't get it and maybe I don't even want to know all that I did because I gotta tell ya, it is very very scary and I am going to tell everyone I know to stay away from Ambien. It is a hypnotic and although it might not happen with enough frequency for the FDA to pull it off the shelves I can't help but wonder how many other zombies are out there sleep driving and putting their lives and the lives of others at risk while taking this stuff?????? No more Ambien for me ever. I think I prefer insomnia. And some people never figure it out because it's difficult to figure it out because you don't remember anything. I say I'm lucky because I was able to diagnose "my problem" on my own but honestly have no idea how many times it happened....very scary stuff.

    By Blogger Susan J., at 1/29/2009 06:57:00 PM  

  • this is amazing stuff. I've been on ambient for a couple of years and it works great. Recently when I didn't take it on my nights off I've experienced serious nightmares to wake up with my heart pounding. I don't think the hallucination part of this drug has been explored enough. I don't know if the mind is making up for the lack of dreams during the time while you are under the medication or it's just a residual of some aspect of the drug. For a potentially weak minded individuals these nightmares or hallucinations could possibly lead to paranoia or even schizophrenia. The dreams seem very real!!! I'm stopping my ambient intake today. I hope the withdrawal will not be too unbearable!!!

    By Anonymous Anonymous, at 2/16/2009 02:18:00 PM  

  • i was in a car reck while working i hit my head hard and suffered from not doctor gave me ambian.for 20 nites but when it was done i got it for a ew months more.anyway i was just told i had taking on the phone doing regular activities that i do not remember talking in anger being frustrated.mgirlfriendtold me this i onlt remember flash backs but i thought i was dreaming cuz i was asleep.last thing i did was take my ambian went to bed and my girlfriend left but i was lil upset at her.when i fell asleep that is all i remember.when i woke up my room was detroyed.i later found out i raped my girlfriend.i wasent myse;f at all how i talked acted.she said my eyes looked very glassy.i am just upset that i did this and hurt her.i never been that type to be so violent.and i was never told i would do these things.hasany1been violentor killedany1who was in the influence on ambian

    By Anonymous Anonymous, at 11/08/2009 10:37:00 AM  

  • I had trouble functioning during the day because I couldn't fall asleep until 1 or 2 am, then had to get up at 6 am. My doctor prescribed 10 mg Ambien (not CR) but because I'm small I decided to cut one in half the first night. I was able to sleep soundly almost immediately after my head hit the pillow and I slept all night. That was about three years ago and I am still taking my half pill per night and sleeping well. I have occasional times (maybe once every two months) that I don't sleep well with them, but I don't blame the pill for that. Follow the directions, if you don't it isn't the fault of the drug, it's your own fault.

    By Anonymous ambien, at 10/25/2010 03:14:00 PM  

  • My insomnia comes from anxiety issues when I try to sleep. I found that Ambien didn't make me sleepy but it did relax me enough to fall asleep. There are tons of stories floating around about strange behavior and I have my share. I found this only happens when I try to do things between ingestion and onset. Only take it when you are already in bed, relaxing, and attempting to fall alseep, and you shouldn't have any problems.

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  • When I wake up in the morning I'm suprirse by what I've done, but I do retain a vague dream-memory of what I was doing. I don't remember why I did it, but I do - vaguely - remember doing it, and having had a reason at teh time.

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