The relationship of dreaming to memory consolidation

during sleep, and to pre- and post-sleep cognition

Professor Mark Blagrove

Sleep Laboratory

Department of Psychology

Swansea University

• Background: Sleep, memory & dreaming

• Possible functions of dreaming, or no

function

• Dreaming, metaphor and insight

• Post-sleep effects of considering and

sharing dreams

• Background

• Slow Wave Sleep and REM sleep are

involved in memory consolidation during

sleep

• Replay of memories in HC during sleep

• Memory consolidation is greater for salient

or important materials

Welsh language recall across 12 hours

wake or 12 hours incl sleep

Van Rijn et al., 2017, J Sleep Res

Lesion sites associated with loss of dreaming but

preserved REM sleep (Solms, 1997)

• Possible functions of dreaming

• Hartmann E (1995). Making Connections

in a Safe Place: Is Dreaming

Psychotherapy? Dreaming, 5: 213-228.

• Dreaming and psychotherapy involve the

freeing of associations, without acting out,

in a safe environment.

• Dreaming and psychotherapy can make

connections between trauma and other

relevant memories. Dreams at first replay

the trauma, but then change to include

related material, using metaphor.

• During this change the same dominant

emotion remains

• Dreaming makes more broad and

peripheral connections than does waking

thought

Another theory is…..

• Revonsuo’s (2000) Threat simulation

theory.

• This is a virtual reality theory, as opposed

to mnemonic or emotional processing

theories

• This theory holds that dreaming is a

selective simulation of the waking world

and its threats

• In dreaming we practice overcoming the

threats

• Revonsuo et al. (2015) have now

amended this theory to include dreaming

being a simulation of social reality, as well

as of physical threats.

• Links to memory consolidation in general

That dreaming might reflect functional

neural processes during sleep results

in the following bold statement:

“Dreaming is the poor man’s fMRI!”

Bob Stickgold, 2012

Dream content as a function of hours of TV

watched on 9/11 (Propper et al., 2007)

• They speculate that the dream content

was related to unresolved emotion from

TV watching, as effect was not found for

length of time spent talking about it on the

day

Often cited as support for

dreaming having a beneficial

effect / function

• Wamsley et al, (2010) Current Biology

• Dreaming of a Learning Task Is

Associated with Enhanced Sleep-

Dependent Memory Consolidation

• Hypothesized that dreaming in NREM sleep about learning a virtual navigation maze task would be associated with improved performance across sleep on the task.

• Memory improved across sleep, compared

to across wake.

• Improved performance at retest was

strongly associated with task-related

dream imagery during the nap.

However

• Task-Related reports were not veridical reiterations of the learning experience

• The reports were unquestionably related to the maze, but consisted of remote associations and memories thematically related to the task.

• Maybe memory consolidation is highly

associative

• Or maybe dreams reinstate the context of

learning, like the context of an odour,

allowing re-excitation of what was learnt.

• An endogenous ‘Targeted Memory

Reactivation’

• Most important objection to Wamsley et al,

2010, and to their J Sleep Research (in

press) replication, is that dreaming of the

task was also correlated with pre-sleep

low performance

• So dreaming might not reflect or be related

to a within-sleep brain function

• Similar to DeKoninck (2012) and language

learning, we dream of mistakes

What does it mean to say

dreaming has a function?• It means the hypothesis that we have

evolved to have dreams of a particular

type. People with those dreams have a

reproductive advantage.

• For most such theories, dreams that we do

not remember on waking, or that occurred

while we remained asleep, do something

beneficial for us.

But why propose a function?

• Nielsen & Levin: we dream of waking life so as to extinguish fear memories

• Revonsuo: we dream of threats so as to practice overcoming them

• Hartmann: we dream of waking life emotional events so as to connect memories more widely

• The null hypothesis: we just dream of waking life

• The null hypothesis has two versions:

• Dreams are similar to waking life and

reflect our waking life thinking, the

continuity theory of Domhoff and Schredl,

or

• Dreams are a scrambled version of waking

life memories, as in Hobson’s Activation-

Synthesis theory

Is there still a possibility of dream

function?

• Maybe higher level learning / restructuring /

interpersonal emotional social learning is

occurring in REM sleep and is reflected by

dream content.

• Maybe we are dreaming of social learning, e.g.,

why was I being tested on that maze, how was I

treated, how do I feel?

• After all, dreams are very social, often with many

characters

• Hu et al. (2015).

• Cognitive neuroscience. Unlearning implicit social biases during sleep.

• Science, 348(6238):1013-5.

• This form of social memory consolidation could be related to the plot, characters and emotions of dreams

• But this learning usually has long time scales and the cue for it can also be temporally diffuse, unless it is a trauma, so it is difficult to study

• Evidence from the dream-lag effect, the

delayed incorporation of waking life

experiences into dreams, might support a

memory consolidation function of

dreaming

Nielsen et al. (2004, J Sleep Res)

The time course for the incorporation of recent naturalistic events into dreams has shown day-residue and dream-lag effects

The nature of delayed dream incorporation (‘dream‐lag effect’): Personally significant events persist, but not major daily activities or

concerns

The nature of delayed dream incorporation (‘dream‐lag effect’): Personally significant events persist, but not major daily activities or concerns, First published: 22 April 2018,

DOI: (10.1111/jsr.12697)

Fig. 1. Design of experiments. Experiment 1 – participants kept a daily log for 10 days before having dream reports collected during

one night in the sleep laboratory or at home. Experiment 2 – participants kept a diary of dreams spontaneously recalled at home...

E. van Rijn, J.-B. Eichenlaub, P.A. Lewis, M.P. Walker, M.G. Gaskell, J.E. Malinowski, M. Blagrove

The dream-lag effect: Selective processing of personally significant events during Rapid Eye Movement sleep, but not

during Slow Wave Sleep

Neurobiology of Learning and Memory, Volume 122, 2015, 98–109

http://dx.doi.org/10.1016/j.nlm.2015.01.009

Fig. 3. Mean number of incorporations of the instrumental awakenings night into home dream reports for participants in the sleep

laboratory group who recorded the impending experimental night as being a major concern. Incorporations are identified by

participa...

E. van Rijn, J.-B. Eichenlaub, P.A. Lewis, M.P. Walker, M.G. Gaskell, J.E. Malinowski, M. Blagrove

The dream-lag effect: Selective processing of personally significant events during Rapid Eye Movement sleep, but not

during Slow Wave Sleep

Neurobiology of Learning and Memory, Volume 122, 2015, 98–109

http://dx.doi.org/10.1016/j.nlm.2015.01.009

• Difficulty here is studies of relationship

between dream content and any waking

life change are correlational, they can’t

show causation

• We can’t yet assign participants randomly

to dream content conditions so as to see if

that content has any effect

• But a 2017 paper might lead to work that

gives clues as to whether dreaming has a

function

• Within-subjects multiple awakenings design

• Dreaming occurs in NREM and REM sleep when

the posterior ‘hot spot’ changes activity.

• Hot-spot activity can even predict dream / no

dream on awakening

• Next step is to find out why the hot spot is turned

on.

• Is virtual simulation of the world sometimes

needed to complete/enhance emotional memory

processing?

Dreams are decorative ‘spandrels’

• Flanagan and Domhoff and Schredl:

dreaming is an epiphenomenon, like the

noise from a factory, or a by-product of

waking life imagination.

• But it is a complicated by-product!

• Domhoff: Dreams are embodied

simulations that dramatize conceptions

and concerns.

APA journal

Dreaming, 2017

• Domhoff’s view is that there is non-

functional embodied enactment of waking

life conceptualizations and concerns.

• Dreaming includes long-term concerns

and past misfortunes, including dreaming

of long-deceased loved ones, that

Domhoff & Schneider say are not

characteristic of SST ‘forward-looking

social rehearsal’.

• Despite dreaming and dream formation

being so complex….

• We don’t know if dreaming has a function.

• Unrelated question:

• Can the consideration of dreams give

insight or self-awareness?

Dream content, creativity and

insight

• This is a completely different issue from

whether dreaming / REM sleep / sleep has

a cognitive, memory, emotional or virtual

reality function!

Some evolutionary

function

Yes No

Can be

source of

insight

Yes Hartmann Freud

No Hobson;

Revonsuo

Flanagan

Domhoff

Claims of dreams and insight

• For example, the claimed insight of Kekulé

about the circular shape of the benzene

ring after dreaming of a snake eating its

own tail

Measuring insight and creativity

• There are many difficulties

• Assessing novelty and validity of the

insight or creativity

• E.g. Stockhausen

• In 1991 he was commissioned to compose a string quartet

• “And then I had a dream. I heard and saw the four sitting players in four helicopters flying in the air and playing. At the same time I saw people on the ground seated in an audio-visual hall, others were standing outdoors on a large public plaza.”

• This led to his Helicopter Quartet, in which

each of the four members of a string

quartet is in a helicopter, the sound of its

rotating blades being mixed with the sound

of the strings.

• To investigate such claims it must be clear

that creativity or insight has occurred

• Allan Hobson: “I never learned anything

from a client’s dreams that I did not

already know.” (in Hobson & Schredl,

2011)

• Use Ullmann Dream Appreciation

technique

Found two types of insight

• A distinction can be made between:– Insight about the sources of an item of dream

content: “Aha, this is where that part of the dream came from.”

– Insight about one’s waking life as a result of considering the dream: “Aha, this tells me this about myself”.

• The Gains from Dream Interpretation questionnaire exploration-insight subscale assesses these, and engagement in working with the dream

Control conditions needed

• Someone else’s dream

• A waking life episode

• Because it may be the process and time

given to interpretation that may result in

insight or creativity, rather than the dream

itself – (Clara Hill et al, 1993)

• In Blagrove et al. (in press, APA’s Psychology of Consciousness), participants claim that approximately 50% of dream discussions provide some insight about the dreamer or their life. The insight might not be astounding, but the dream content acts as a reminder, a reference to what might be being ignored, and it may do so in a metaphorical way

• It may be that any new metaphor will

provide some restructuring of waking life

knowledge, even if the waking life issues

are quite well known and already well-

considered and explored.

They may (just) raise

awareness

• “Homophobia” (coined 1971)

• We knew it already, but the new word

moves awareness on, increases it, a little.

New phrase

• “Check your priviledge”

• It is consciousness-raising, increasing

awareness, it is reminding.

• What is new is that you didn’t have that

reminder. That might be one type of

insight that dreams give.

An Example

• The capitalized tweet dream!

• The play, Harry Potter and the Cursed Child

Extensive literature on dreams

and metaphor• Lakoff (1993, Dreaming). How metaphor

structures dreams: the theory of the

conceptual metaphor.

• Malinowski and Horton (2014, Frontiers in

Psychology). Metaphor and

hyperassociativity: the imagination

mechanisms behind emotion assimilation

in sleep and dreaming.

• But beware Timpanaro’s (1976) The Freudian Slip critique, re Aliquis slip in Freud’s Psychopathology of Everyday Life

2011, APA journal Dreaming

• Can there be a benefit, such as one of

increasing self-awareness, possibly

mediated by metaphorical content, if we

consider or share our dreams?

• What if we gave the dreamer a drawn

illustration of the dream, to return to

across time, on their own or with

significant others?

• Just as people return to and lend or

recommend their favourite film

The analogy with films

• The film can be impactful

• It can generate (metaphorical)

understandings and insights and

reconceptualisations

• You can see it repeatedly

• You can recommend it to friends

• You can show it to friends

• You can loan the DVD to friends

• How you view it over time can change

• The illustration is made during a 40 - 50

minute discussion about the dream.

• The artist Julia Lockheart and I have been

doing this, starting at the British Science

Festival in September 2016

• The aim had / has been to elicit insight in

the dreamer, give them a record of an

impactful dream to share with others.

• But in doing the project we started to

realise the effect the discussions were

having on us, and could have on the

significant others of the dreamers.

• We speculate that increased empathy on

discussing a dream with someone and

relating it to their waking life is mediated

by the dream being fiction.

• Keith Oatley and Raymond Mar in

Toronto, and others, have shown a

relationship between engaging with fiction

and increased empathy

• They state that the reader sympathizes

with the characters in the story, through

taking the perspective of the characters,

and experiences the events as if they are

the reader’s own experience.

• But they state that this effect only occurs if

the reader is fully immersed into the story,

‘transported into this narrative world.’

• They state that the emotional response is

greater than with non-fiction, because of

the involvement with the characters and

story, and because ‘the focus of fiction is

primarily on eliciting emotions, rather than

on presenting factual information...’

2016

• Oatley concludes: ‘While some everyday

consciousness can remain inside the

individual mind and be externalized in

small pieces during conversations, fictional

stories can be thought of as larger pieces

of consciousness that can be externalized

by authors in forms that can be passed to

others so that these others can internalize

them as wholes, and make them their

own.’

• The dream simulation, which has social

content, can similarly be passed to others

who internalize it

• Dreams are fictional because they have

scenes and characters but don’t copy

waking life episodes:

• Fosse, Fosse, Hobson and Stickgold

(2003). Dreaming and Episodic Memory: A

Functional Dissociation? J Cognitive

Neuroscience.

Fig 2. Characters and places of the dreams.

Vallat R, Chatard B, Blagrove M, Ruby P (2017) Characteristics of the memory sources of dreams: A new version of the content-

matching paradigm to take mundane and remote memories into account. PLOS ONE 12(10): e0185262.

https://doi.org/10.1371/journal.pone.0185262

http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0185262

• The similarity between story production

and dreams is detailed in Bert States’

(1993) Dreaming and Storytelling

• And in:

• The dream might thus act as a piece of

fiction, that others explore with the

dreamer and that, like is proposed for

literary fiction, can then induce interest in

and empathy about the life of the dreamer.

Caveat from Toronto empathy team

• “There is nothing more boring than

listening to someone else’s dream!”

• In a recent study we found that Trait empathy was significantly associated with frequency of listening to the dreams of others (r=.14, p=.045), frequency of telling one’s own dreams to others (r=.32, p<.001), and positive attitude towards dreams (r=.29, p<.001).

• Future studies should investigate the effect on state empathy of experimental alterations in frequency of telling and listening to dreams.

• Increased dream telling might counteract current societal decreases in empathy, in that empathic concern and perspective taking, the main two components of empathy, have greatly diminished between 1979 and 2009 (Konrath et al., 2011).

• Konrath, S.H. et al. (2011). Changes in dispositional empathy in American college students over time: a meta-analysis. Personality and Social Psychology Review, 15, 180-98.

•

Within-sleep function theories

• Dream production is complex:

• Threat simulation

• Fear extinction

• Weak or novel associations are created

• And at the point of dream production,

dream function occurs.

• This empathy effect occurs later than

dream production, when we are awake

and share the dream.

• So far the proposal for this effect is

plausible.

• Now a more speculative aspect.

• Could the fictional / story-like characteristic of dreams have been enhanced in evolution, and in particular by sexual selection, as part of the selection for emotional intelligence and empathy?

• This would be on a timescale similar to that for language, storytelling and group cohesion and cooperation in humans (Smith et al., 2017).

• Smith, D. et al. (2017). Cooperation and the evolution of hunter-gatherer storytelling. Nature Communications, 8, 1853.

• There would thus be similarities between

the told dream simulation and blushing, in

that both signal the emotional state of the

dreamer/blusher to others, and hence both

are subject to selective pressure.

• Because the blush is involuntary, it is a

believable signal about regret and not

wishing to transgress in the future

(amongst the signalling of other emotions).

• This possible function of dreams would

utilise the social characteristics of the

simulation/dream, when the

simulation/dream, on waking, is told to

others.

• It may also utilise the architecture of sleep:

• Implication for the science of

consciousness

• As with dreaming, theories of waking life

consciousness range from epiphenomenal

to first-person accessing of neural

processing, to thinking about and

imagining the past and the future, and

error detection (spotting the unexpected)

• Maybe a further function of human

consciousness is passing on our vignettes

to others, so they can internalize and

understand and sympathise with one’s

own experiences