Dreams Part II – What else is oneirology telling us about the function of dreaming?

by Mark Redmond

A previous Inside Out article focused on the hypothesis that dreams process unresolved emotional responses to new or past experiences (Redmond, 2023). This article will briefly review other dream theories that have appeared in the literature since the turn of the millennium, but due to the pressure of space will not include critique by other theorists. The review will also not explore lucid dreaming or parasomnias, both of which offer interesting insights into dreaming consciousness. The review is not an attempt to shoehorn dreams into theoretical boxes or diminish their mystery and wonder with scientific reductionism; rather it is my curiosity running free as I try to understand consciousness via an exploration of the paradox of sleep – the intrusion of consciousness/wakefulness into sleep. There is an ongoing debate between biologists, cognitive neuroscientists, and clinically orientated psychologists as to the function of dreams. There are two general dream theory categories; the first is the in-sleep dream theories where the function of dreaming is independent of remembrance, and the second is where the function is only present when dreams are processed post-sleep. In-sleep dream theories are hard to test empirically and are accused of relying on associated findings that cannot show causation, whereas post-sleep theories are more amenable to testing.

To begin, I will briefly summarise the central hypothesis outlined in the previous article. This is encapsulated in what Hartmann (2014) calls The Contemporary Theory of Dreaming, which posits that dreaming is a sleeping form of consciousness that is guided by emotions and uses picture-metaphor to make broad connections in neural networks to help weave new or unresolved past emotional experiences into existing memory systems. Hartmann (1995, 1996) equates dreaming to the process of psychotherapy where connections are made in a safe place. What follows are other dream theories from the literature that have caught my attention.

Continuity Theory

The Continuity Theory is one of the most widely studied models of dreaming which posits that dreams are psychologically meaningful and continuous with waking concepts and concerns. The first mention of continuity and dreams was pre-Freudian and made by Calkins (1893), though it was dream researchers Bell and Hall (1971) who published the concept in a more concrete form. More recently the theory is associated with Schredl (2006, 2010, 2012) who also defended it in a discussion with Hobson (Hobson & Schredl, 2011). Domhoff (2010) points out that with continuity

Much, but not all, dream content is continuous with the dreamer’s waking concerns and interests. The most direct continuities involve the main people in a dreamer’s life and the nature of the social interactions with them. (p. 5)

The opposites to continuity theories of dreams are the ones that consider ‘discontinuity’ which seek to account for bizarreness and “elements that the dreamer has never experienced in his waking life, e.g., flying, pain experiences, hearing in congenitally deaf person etc.” (Hobson & Schredl, 2011, p. 6).

Activation-synthesis, AIM Model and proto consciousness.

Activation-Synthesis, a neurobiological theory by Hobson and McCarley (1977), was openly anti- Freudian and posited that dreams are meaningless and the result of largely random firing in the brainstem (activation) and the higher brain’s efforts to make sense of it (synthesis). Hobson (1999) called dreaming “a physiological Rorschach test … What we see, feel, and do in our dreams reveals our specific and personal predilections” (p. 93). As technology has developed, the hypothesis has undergone an evolution leading to the three-dimensional AIM Model (Hobson, 1999, 2009; Hobson et al., 2000), which accounts for all forms of consciousness or brain-mind states such as waking, dreaming, delirium, psychosis, etc. These diverse brain-mind states are variations of three variables:

1. Activation – The amount of electrical activity in the brain as measured by electroencephalography (EEG).

2. Information – Is data coming from the outside world via the senses and perceptions or internally from stored images and imagination?

3. Mode – Whether the aminergic or cholinergic system is powered up. The aminergic- cholinergic system modulates cognition – attention, volition, and insight, which all differ radically between waking and dreaming.

Hobson (2009) defines primary consciousness as simple awareness of perception and emotion and secondary consciousness as the capacity for abstract thinking, self-reflection, and metacognition. Rapid eye movement (REM) dreams have primary consciousness only and may constitute a “proto conscious state” (p. 803) providing a virtual reality model of the world that is of functional use to the development and maintenance of secondary consciousness and could have a role in brain development.

In humans the amount of REM sleep peaks in the third trimester of gestation and plummets after birth, as waking time and cognitive capability increase. Thus, primary consciousness declines and secondary consciousness grows with the development of the brain and the capacity for prolonged waking. (Hobson, 2009, p. 804)

Hobson’s (2009) hypothesis accounts for discontinuity and is future orientated since the developing brain may be self-activating in a way that anticipates its later, wake-state operation. Hobson’s (2009) hypothesis builds on the work of Jouvet (1973), who proposed that REM sleep promoted the rehearsal of instinctual behaviour.

Neurocognitive Theory

Neurocognitive Theory, which builds on the Continuity Theory, was first published by Domhoff (2001, 2003) at the turn of the millennium and has since been refined in line with data emerging from ongoing innovations in neuroimaging technology (Domhoff, 2010, 2019a, 2019b). Theories such as Activation-Synthesis posit that brain regions for dreaming and waking cognition are different, whereas Neurocognitive Theory explores commonality in active brain locations for diverse brain-mind states. The region of special interest is the default network (default mode network augmented by secondary visual and sensorimotor cortices), which is more active when engaged in passive cognitive tasks such as waking fantasy, mind wandering and dreaming (Domhoff, 2011; Domhoff & Fox, 2015). Recognising the findings of Foulkes (1999) on children’s dreams, the theory views dreaming as a gradual cognitive achievement “that depends upon the development of cognitive abilities that are also important in waking life” (Domhoff, 2010, p. 4). Domhoff (2010, 2019a, 2020) believes that dreams do not have an adaptive function, but do have “psychological meaning, and they therefore can portray central emotional preoccupations in creative and dramatic ways, but this does not necessarily mean that they have a purpose” (Domhoff, 2010, p. 8). However, Domhoff (2010) recognises that many cultures have developed ‘uses’ for dreams, including creative inspiration and personal exploration.

Threat Simulation Theory

For Revonsuo (2000), the only appropriate dream function theories are those that are biological, adaptive, and therefore ‘natural’ as opposed to ‘invented’, which provide psychological adjustment to an individual incarnation only: i.e., they are “invented by us, not by natural selection” (p. 879). The lifespan of our early ancestors was short, their habitat full of predators and they possibly lived in a continuous post-traumatic state, so any advantage for survival or reproductive success would have been selected by evolution. Switching the context in this way, Revonsuo (2000) posits that the biological function of dreaming “is to simulate threatening events, and to rehearse threat perception and threat avoidance” (p. 877), and if, “dreaming does have any biologically adaptive functions, they must have been effective in the evolutionary context” (p. 878). Revonsuo (2000) is careful to point out that not every dream will have this function; only real threatening events will fully activate the threat simulation system. The theory has since been extended to include simulations of social reality in a new theory called the Social Simulation Theory (Revonsuo et al., 2015), which posits that the dreaming self is an avatar in a simulated social reality endeavouring to master social skills.

Dreaming as overnight therapy

The theory of overnight therapy for REM dreams (Walker, 2018) postulates that dreams help remember salient experiences by integrating them with existing knowledge and putting them into autobiographical perspective. A second function is, “to forget, or dissolve, the visceral, painful emotional charge that had previously been wrapped around those memories” (p. 206). Key to this processing is the neurochemically calm, (i.e., low noradrenaline) safe dream brain environment of REM sleep. Walker (2018) posited that the anxiety associated with PTSD disrupts this safe sleep environment and a fortuitous encounter with Raskind confirmed his hypothesis. When treating PTSD patients with the drug Prazosin for high blood pressure, Raskind et al. (2013) noticed as a side effect that it suppressed noradrenaline in the brain which helped to alleviate re-occurring PTSD nightmares.

Neuro-psychoanalysis

Though not a theory per se, the work of Solms (2021) is worthy of inclusion in this review. His brain lesion studies identified the mesocortical-mesolimbic dopamine circuit as the driver of dreaming. This is the ‘seeking system’, responsible for our motivated actions in relation to survival and our desires. According to Solms (2021), this demonstrates that Freud was on the right track with the wish-fulfilment view of dreams. The neurons driving the seeking system circuitry originate from the brainstem, therefore linking the mid-brain and brainstem as brain correlates of dreaming. Solms (2021), an advocate for a neuro-psychoanalysis approach to consciousness research, is critical of many contemporary approaches that treat personal memory content just like that in a mobile phone, excluding consciousness and the subjectivity of the human experience.

Network Exploration to Understand Possibilities (NEXTUP)

In their recent publication, Zadra and Stickgold(2022) present their NEXTUP dream function hypothesis, which posits that dreaming is “a unique form of sleep dependent memory processing that extracts new knowledge from existing memories through the discovery and strengthening of previously unexplored weak associations” (p. 108). Due to the demands of waking experience, focused waking thought tends to ignore these weaker associations and therefore misses possibilities for connection making. This theory pays homage to Hartmann and Cartwright’s view that dreams regulate negative emotions by making neural connections with previous experiences in memory. It also integrates Stickgold’s et al. (2001) memory consolidation theory of dreams and, in particular, research that demonstrated the preference for connection making via weaker associations (Stickgold et al., 1999). This searching through weaker associations also explains dream bizarreness. The main feature of NEXTUP is that dreaming is future oriented and that the goal of memory consolidation is not for accurate recall, but to better remember what will possibly be most useful in the future.

Empathy function and human self-domestication

After many years of post-sleep dream processing using the Ullman (2006) dream discussion method in groups, Blagrove started to notice the ‘empathic effect’ of dream sharing for dreamers and listeners (Blagrove and Lockheart, 2023b). This observation was strengthened further when hosting ‘DreamsID events’ (Blagrove and Lockheart, 2023a), which showed that discussing a dream in a group influenced all participants. Subsequent research on dream sharing and empathy did indeed demonstrate that ‘trait empathy’ (the ability to show empathy as a personal trait, as opposed to ‘state empathy’ which is the transient affective reaction elicited in concrete situations) is significantly correlated with the frequency of telling dreams to others, the frequency of listening to others’ dreams, and that dream sharing increases empathy in the listener/discusser toward the dream sharer (Blagrove et al., 2019; Blagrove et al., 2021). They concluded that: “These findings of post sleep, social effects of dreaming, with possibly a group bonding function, go beyond theories of dreaming that have a within-sleep emotional or memory processing function for the individual” (Blagrove et al., 2021, p. 128). Blagrove and Lockheart (2022, 2023b) posit that in early humans, dreaming may originally have had a memory consolidation, threat rehearsal function or simply been a ‘spandrel of sleep’. But with mounting evolutionary pressure, dreaming became part of human self-domestication (Hare, 2017; Shilton et al., 2020), with the fictional and story like aspect of dream content selected to promote empathy and social bonding via post-sleep sharing of dreams with others. Blagrove and Lockheart (2022, 2023b) provide strong arguments linking dream function to human self-domestication, citing the work of Shilton et al. (2020) who emphasise the importance of storytelling during our evolutionary social development, and the work of Boyd (2018) who highlights the role of fictional story telling in human self-domestication. For Boyd, “there would be a craving for understanding our world not only in terms of our own direct experience, but through the experience of others, whether those others were real or, as occurs in fiction, imagined” (Blagrove & Lockheart, 2022, p. 89).

The Embodied Cognition Theory of Dreaming (ECTD)

Wagener, an assistant professor of counselling, presents a dream function hypothesis slightly similar to Hobson’s (2009) Proto consciousness Theory. Wagener (2023) views dreams as preparations for an individual’s waking life and builds on the theory of embodied cognition and embodied metaphor. Wagener (2023) posits three reasons for dreaming:

The first is to organise schemas congruent with individuals’ affective and sensorimotor understandings of self-in-context. The second is to prepare individuals to react to schemas, and the third is to prepare individuals to use sensorimotor processes likely to be needed in waking experience. ECTD posits that dreaming exists to prepare individuals to react to the types of experiences that were affectively significant in waking. (Wagener, 2023, p. 35)

Discussion

Each dream theory presented here has unique features but a general theme running through many seems to be the mastery of emotions or skills that may be of relevance to the future. The neural correlates of dreaming are hard to pin down; some theories locate the origins of dreaming in the cortex, others in the mid-brain and others in the brainstem. This review has demonstrated that there is no research on the function of dreaming from a psychotherapeutic perspective, possibly due to the dominance of the reductionist scientific paradigm that views non-evolutionary ‘invented functions’ (see Threat Simulation Theory) as irrelevant. Jung (2007) would disapprove. He would agree that the purpose of the morning of life is important for the biological survival of our species, but the second half of life (the afternoon) is important for individuation and the advancement of culture, which is important for the long-term survival of our species. Considering the Anthropocene and the threat the human species now puts on the biosphere, it is time for conscious evolution (Hubbard, 2015) and research should now, out of necessity, focus more on the ‘invented’ rather than the ‘natural’ functions.

Conclusion

If all theories are valid, then there are many forms of dream consciousness that involve diverse brain regions. Indeed, Proto consciousness theory indicates the existence of a primordial state of brain organisation that is a possible building block for consciousness. However, regardless of whether dreaming has a function or purpose in addition to that of sleep, dreaming has a use in creative inspiration and personal exploration in our culture. It is heartening as a psychotherapist to see the advancement in the last few years of the Empathy Function and Embodied Cognition theories of dreaming. I am also heartened that the essence of The Contemporary Theory of Dreaming is still present in some of the more recent theories presented. Research from a psychotherapeutic perspective is warranted as it would bring a new perspective to the ongoing debate on the function/purpose/use of dreaming.

Mark Redmond MIAHIP, Dip. Counselling and Psychotherapy, MSc (Loss and Bereavement), BTech. Mark works in private practice in south Wexford and in cancer support. He likes working with dreams and nightmares and can be contacted at info@markredmond.ie.

Mark Redmond MIAHIP, Dip. Counselling and Psychotherapy, MSc (Loss and Bereavement), BTech. Mark works in private practice in south Wexford and in cancer support. He likes working with dreams and nightmares and can be contacted at info@markredmond.ie.

References: 

Bell, A. P., and Hall, C. S. (1971). The personality of a child molester: An analysis of dreams. Transaction Publishers.

Blagrove, M., Hale, S., Lockheart, J., Carr, M., Jones, A., and Valli, K. (2019). Testing the empathy theory of dreaming: The relationships between dream sharing and trait and state empathy. Frontiers in psychology, 10, 1-13. https://doi.org/10.3389/fpsyg.2019.01351

Blagrove, M., and Lockheart, J. (2022). Dream-sharing and human self-domestication. International Journal of Dream Research, 15(1), 86-94. https://doi.org/10.11588/ijodr.2022.1.83442

Blagrove, M., and Lockheart, J. (2023a). The science and art ofdreaming. DreamsID.com https://dreamsid.com/index.html

Blagrove, M., and Lockheart, J. (2023b). The science and art of dreaming. Routledge.

Blagrove, M., Lockheart, J., Carr, M., Basra, S., Graham, H., Lewis, H., Murphy, E., Sakalauskaite, A., Trotman, C., and Valli, K. (2021). Dream sharing and the enhancement of empathy: Theoretical and

Boyd, B. (2018). The evolution of stories: from mimesis to language, from fact to fiction. WIREs Cognitive Science, 9(1), 1-16. https://doi.org/10.1002/wcs.1444

Calkins, M. W. (1893). Statistics of dreams. The American Journal of Psychology, 5(3), 311-343. https:// doi.org/10.2307/1410996

Domhoff, G. W. (2001). A new neurocognitive theory of dreams. Dreaming, 11(1), 13-33. https://doi. org/10.1023/A:1009464416649

Domhoff, G. W. (2003). The scientific study of dreams: Neural networks, cognitive development, and content analysis. American Psychological Association. https://doi.org/10.1037/10463-000

Domhoff, G. W. (2010). The case for a cognitive theory of dreams. The DreamResearch.net Dream Library. https://dreams.ucsc.edu/Library/domhoff_2010a.html

Domhoff, G. W. (2011). The neural substrate for dreaming: Is it a subsystem of the default network?

Consciousness and cognition, 20(4), 1163-1174. https://doi.org/10.1016/j.concog.2011.03.001 Domhoff, G. W. (2019a). The neurocognitive theory of dreams at age 20: An assessment and a

comparison with four other theories of dreaming. Dreaming, 29(4), 265-302. https://doi. org/10.1037/drm0000119

Domhoff, G. W. (2019b, March 22). Book preview: The neurocognitive theory of dreaming: Where, how, when, what, and why. [Conference paper] Annual Meeting of the Society for the Neuroscience of Creativity 2019, San Francisco, California, United States.

https://dreams.ucsc.edu/NCTD/Neurocognitive_Theory_of_Dreaming_SNC2019.pdf

Domhoff, G. W. (2020). Dreaming is imagination roaming freely, based on embodied simulation, and subserved by an unconstrained default network. In A. Abraham (Ed.), The Cambridge handbook of the imagination (pp. 676-691). https://dreams.ucsc.edu/Library/domhoff_2020b.pdf

Domhoff, G. W., and Fox, K. C. R. (2015). Dreaming and the default network: A review, synthesis, and counterintuitive research proposal. Consciousness and cognition, 33, 342-353. https://doi. org/10.1016/j.concog.2015.01.019

Foulkes, D. (1999). Children’s dreaming and the development of consciousness. Harvard University Press.

Hare, B. (2017). Survival of the Friendliest: Homo sapiens evolved via selection for prosociality. Annual Review of Psychology, 68(1), 155-186. https://doi.org/10.1146/annurev-psych-010416-044201 Hartmann, E. (1995). Making connections in a safe place: Is dreaming psychotherapy? Dreaming, 5(4),

213-228. https://doi.org/10.1037/h0094437

Hartmann, E. (1996). Outline for a theory on the nature and functions of dreaming. Dreaming, 6(2), 147-170. https://doi.org/10.1037/h0094452

Hartmann, E. (2014). The nature and functions of dreaming. Oxford University Press. Hobson, J. A. (1999). Dreaming as delirium: How the brain goes out of its mind. The MIT Press.

Hobson, J. A. (2009). REM sleep and dreaming: towards a theory of protoconsciousness. Nature Reviews Neuroscience, 10, 803-813. https://doi.org/10.1038/nrn2716

Hobson, J. A., and McCarley, R. W. (1977). The brain as a dream state generator: an activation-synthesis hypothesis of the dream process. The American Journal of Psychiatry, 134(12), 1335-1348. https:// doi.org/10.1176/ajp.134.12.1335

Hobson, J. A., Pace-Schott, E. F., and Stickgold, R. (2000). Dreaming and the brain: Toward a cognitive neuroscience of conscious states. Behavioral and Brain Sciences, 23(6), 793-842. https://doi. org/10.1017/S0140525X00003976

Hobson, J. A., and Schredl, M. (2011). The continuity and discontinuity between waking and dreaming:

A dialogue between Michael Schredl and Allan Hobson concerning the adequacy and completeness of these notions. International Journal of Dream Research, 4(1), 3-7. https://doi.org/10.11588/

18 applied implications. Dreaming, 31(2), 128-139. https://doi.org/10.1037/drm0000165 19

ijodr.2011.1.9087

Hubbard, B. M. (2015). Conscious evolution: Awakening the power of our social potential. New World Library.

Jouvet, M. (1973). Essai sur le rêve. Archives italiennes de biologie, 111(3-4), 564-576. http://www. architalbiol.org/index.php/aib/article/view/111564

Jung, C. G. (2007). Modern man in search of a soul. Routledge. (Original work published 1933). Raskind, M. A., Peterson, K., Williams, T., Hoff, D. J., Hart, K., Holmes, H., Homas, D., Hill, J., Daniels,

C., Calohan, J., Millard, S. P., Rohde, K., O’Connell, J., Pritzl, D., Feiszli, K., Petrie, E. C., Gross, C., Mayer, C. L., Freed, M. C., . . . Peskind, E. R. (2013). A trial of prazosin for combat trauma PTSD with nightmares in active-duty soldiers returned from Iraq and Afghanistan. American Journal of Psychiatry, 170(9), 1003-1010. https://doi.org/10.1176/appi.ajp.2013.12081133

Redmond, M. (2023). Dreams – Making neural connections. Inside Out, 100(1), 40-47.

Revonsuo, A. (2000). The reinterpretation of dreams: An evolutionary hypothesis of the function of dreaming. Behavioral and Brain Sciences, 23(6), 877-901. https://doi.org/10.1017/ S0140525X00004015

Revonsuo, A., Tuominen, J., and Valli, K. (2015). The avatars in the machine: Dreaming as a simulation of social reality. In T. K. Metzinger and J. M. Windt (Eds.), Open MIND. MIND Group. https://doi. org/10.15502/9783958570375

Schredl, M. (2006). Factors affecting the continuity between waking and dreaming: emotional intensity and emotional tone of the waking-life event. Sleep and Hypnosis, 8(1), 1. https://www. sleepandhypnosis.org/ing/Pdf/0c3593dc08ee409cb3a0a3aa6f5a79c6.pdf

Schredl, M. (2010). Characteristics and contents of dreams. International Review of Neurobiology, 92(1), 135-154. https://doi.org/10.1016/S0074-7742(10)92007-2

Schredl, M. (2012). Continuity in studying the continuity hypothesis of dreaming is needed. International Journal of Dream Research, 5(1), 1-8. https://doi.org/10.11588/ijodr.2012.1.9306

Shilton, D., Breski, M., Dor, D., and Jablonka, E. (2020). Human social evolution: Self-domestication or self-control? Frontiers in psychology, 11. https://doi.org/10.3389/fpsyg.2020.00134

Solms, M. (2021). The hidden spring: A journey to the source of consciousness. Profile books.

Stickgold, R., Hobson, J. A., Fosse, R., and Fosse, M. (2001). Sleep, learning, and dreams: Off-line memory reprocessing. Science, 294(5544), 1052-1057. https://doi.org/doi:10.1126/science.1063530

Stickgold, R., Scott, L., Rittenhouse, C., and Hobson, J. A. (1999). Sleep-induced changes in associative memory. Journal of Cognitive Neuroscience, 11(2), 182-193. https://doi. org/10.1162/089892999563319

Ullman, M. (2006). Appreciating dreams: a group approach. Cosimo-on-Demand.

Wagener, A. E. (2023). The embodied cognition theory of dreaming: A proposal for how dreams prepare individuals for waking life. International Journal of Dream Research, 16(1), 35-39. https:// doi.org/10.11588/ijodr.2023.1.90586

Walker, M. P. (2018). Why we sleep: The new science of sleep and dreams. Penguin.

Zadra, A. and Stickgold, R. (2022). When brains dream: Understanding the science and mystery of our dreaming minds. WW Norton and Company.