“So there’s one theoretical framework that says maybe dream content is about simulating and practising through different sorts of threats…”
Maybe dream content is practising this stuff so that you can keep those circuits well oiled, that’s one hypothesis, so one of the consequences of the hypothesis is that people who live in, lets say war torn areas with a lot of violence around them might have an over representation of violence and fighting in dreams, but that study was done just a few years ago comparing people in really terrible areas in South Africa where there is a lot of violence to people somewhere in a wealthy neighbourhood where nothing ever happened and what they found was that there was no difference in their dream content in terms of the level of violence”
Eagleman goes on to say that other research has shown that the content of dreams is pretty consistent across time frames – we have basically the same dreams that our parents, and grand parents and great-grandparents had.
The hypothesis regarding dreams being for simulating and practising through different sorts of threats had me thinking about pain – can we hurt while sleeping and dreaming? (If you don’t want to keep reading, please skip to the comments if you have any direct or indirect of dream pain because I’m very interested in collecting people’s thoughts)
My initial thought was “no!” Pain is a conscious experience and by definition can not be experienced when ‘unconscious’ (I’m aware that the definition of, and distinction between, conscious/unconscious is a can of worms – and it’s one I’m not going to open here).
Checking out the literature didn’t really help – there isn’t too much at all on experiencing pain while you dream, but there were a few interesting nuggets.
Going back some way, in 1966, Nelson asked whether it is possible to tell if one is awake by pinching oneself. Nelson argues that “pain is a mark belonging to waking experiences and never to dream experiences“. However in 1967, Hodges and Carter, in the same publication refute Nelson’s claim and cite a plausible, conceptual example of a dreamer dreaming that he is being burned alive at the stake and awakening to tell his wife of the horrible pain experienced while in the dream. Further, Hodges and Carter propose that it would be possible for a dreamer to be observed moaning and writhing in their sleep and then awaken in a state of perspiration and exhaustion to report of a horrible dream. Both Nelson’s and Hodges and Carter’s arguments turn on philosophical ponderings however and do not provide any empirical evidence.
In 1993 Nielsen et al published some findings in Sleep based on the authors using themselves as the test subjects. They placed an inflatable cuff above the knee of the subject which was then inflated when measurements indicated that the subject was in REM sleep. After waking the subjects and seeking a report on any dream experience, 13 out of 42 reportable dreams included reports of pain sensations.
However, as pointed out in this excellent post from the neurocritic on the subject, the subjects were all primed with the suggestion of pain and were all experienced sleep researchers.
A 2002 paper from Raymond, Nielson et al collected data from the dreams of burns victims while in hospital and found a similar percentage of reportable dreams- about 30%, had an element of pain.
While Nielson and fellow researchers used first-person accounts to explore the subjectivity of pain during dreams, Mazza et al (2012) undertook a review of the literature on nociceptive processing during sleep using third-person observations of sleeping subjects. Mazza et al (2012) suggest that cortical processing of nociception is partly preserved during sleep and reflex behaviours in response to nociceptive stimuli are observable in all stages of sleep.
In one unique case, Mazza et al (2012) report on a subject using a motor activity (lifting an index finger), that had been trained during wakefulness to indicate the perception of a noxious stimulus, following 11 out of 20 stimulus occasions during REM sleep. They do not however, report on the subjective experience of the experiment participant so whether this person experienced pain during sleep is not known.
One very interesting article that came up in my search wasn’t about dream pain, but another complex, subjective phenomenon, that of phantom limb in amputees:
“While dreaming amputees often experience a normal body image and the phantom limb may not be present… Six amputated patients underwent overnight VPSG study. Patients were awakened during REM sleep and asked to report their dreams. Three patients were able to deliver an account of a dream. In all dreaming recalls, patients reported that the amputated limbs were intact and completely functional and they no longer experienced phantom limbsensations. Phantom limb experiences, that during wake result from a conflict between a pre-existingbody scheme and the sensory information on the missing limb, were suppressed during sleep in our patients in favour of the image of an intact body accessed during dream…
So if REM sleep is a state of proto-consciousness (Hobson, 2009), i.e. a contextually (REM sleep) emergent property of self-sustaining systems (the related brain networks), the self as it appears in REM sleep dreams is no longer affected by waking experiences because it feeds from an embodied and functionally intact body scheme.” (Emphasis added)
Reading this I had two thoughts; 1. If, during REM sleep dreams, the “self” is no longer affected by waking experiences and “feeds from a functionally intact body scheme” would any influence of central sensitisation or pain related brain changes be negated during dreaming – do people with CRPS experience allodynic dreams? 2. Is pain also an emergent property of self-sustaining systems (probably as good a definition as any for pain), and does this suggest that pain, as is experienced in the waking state, is just not able to be experienced in a dreaming state?
I’m not convinced that the content of a dream can include the subjective experience that we label pain in a waking state. There is good empirical evidence that nociception occurs when we sleep and that this is “processed” in the brain to some degree, but I’m not persuaded that this is sufficient to be given a label of the subjective experience of pain, even if the nociceptive stimulus is followed immediately by appropriate nociceptive-avoidant behaviour such as withdrawal or other responses such as grimacing or moaning.
One key difference for me is that any reports of pain in a dream are necessarily after the fact. Reports of dream pain are always about pain; meta-comments on what the person remembered of the dream and any pain content. Obviously this is very different from asking a person to report on what they are feeling now, as they feel it. Is the memory of a pain experience pain itself, clearly not. Perhaps there are some answers to these questions in lucid dreams, but whether this is a real dream state or not has its own controversy.
As I sit writing this, I can recall a recent, severe pain experience at the dentist. I can recall what the ceiling looked like, what was being said at the time “this might hurt a little…”, I can recall my response as the ultrasonic scaler hit a patch of exposed dentine and if I really ‘put myself in the experience’ I experience, right now, a shivery, cringing motor output and, for want of a better phrase, a sickening feeling. But, and it’s a big but, I can’t experience the painfulness of the original pain at all (thankfully!!) even though the rest of the experience can be remembered quite vividly. Maybe this is what dream pain is like? All the remembered bits of a past pain experience, what you think pain should be like, but none of the painfulness of waking pain? I’ve never had the experience of dreaming that I was experiencing pain so I’d love to hear from anyone who has.
Let us know in the comments – have you ever dreamt that you were experiencing pain? What about reports from your clients?
Nelson J (1966) Can one tell that he is awake by pinching himself? Philosophical Studies; 17(6)
Hodges M and Carter WR (1967) Nelson on Dreaming a Pain. Philosophical Studies;