There is some positive correlation between experiencing fear during dreams and the ability to manage fear during wakefulness, according to two recently published complementary studies. Whilst not proving a causal link, the results provide a step towards better understanding of the neurophysiological role of dreams. If a causal relationship could be established, it could, potentially, open the way for dreams being integrated in the treatment of anxiety disorders.
It is already known that sleep, irrespective of dreaming, supports emotional management, including through supporting fear extinction learning, which is the reduction in a conditioned response over time, when not reinforced. Less is understood about the specifics of dreaming. It has been theorised that fear in dreams could fulfil a neurobiological function as a form of ‘exposure therapy’. Dream simulations of threatening situations could prepare threat-avoidance skills which can then be adapted in real life, promote fear extinction or desensitisation learning through ‘exposure’ and ‘response’ within the dream or facilitate the resolution of current emotional conflict.
This dream/wakefulness studies, conducted at the University of Geneva, University of Liège and University of Wisconsin, establishes correlation between incidence of fear in dreams amongst healthy participants (all free of neurological or psychiatric disorders) and ‘resistance’ to fear in wakefulness – but, as the authors state and contrary to some media reports: “correlational results cannot be interpreted in a unidirectional and/or causal way. Indeed, we could also suggest that fear suppression during wakefulness may lead to increased excitability of fear‐related experiences during sleep…”
The first of the two complementary studies used electroencephalography (EEG) recordings of brain wave activity to establish that there is correspondence in the activation of neural networks during fear dreaming and, those known activation areas during fear in wakefulness – namely in the insula and the midcingulate cortex (the latter during REM sleep). The authors identified that further studies are needed to establish more specific activations at a subcortical level, for example, in the amygdala.
Existing research suggests that the insula, particularly, the anterior part, plays a part in the experience of conscious feelings and in the emotional response to cognitive or interoceptive signals. The midcingulate cortex is known to play a key role in behavioural/motor responses to threat. These networks’ activation during dreaming occur in a situation where, it is proposed, “memories from a person’s affective history are replayed in the virtual and safe environment.”
The second part of the study, involving some pre-existing study results, sought to show that the high activation of these neural networks during sleep correlated to a less reactive response during wakefulness. Participants’ incidence of fear during sleep, through sleep and dream diaries, was compared with their neurophysiological and emotive responses to negative stimuli, including ‘negative’ facial expressions. Functional magnetic resonance imaging (fMRI) and eye pupil measurement and movement tests were conducted for this.
Amongst participants who reported high incidence of fear during dreams, the results showed decreased activation when responding to fear stimuli, in the insula and amygdala – parts associated with fear and perception of negative emotion, whilst activity of the medial pre-frontal cortex (mPFC) was increased. The mPFC is thought to regulate responses to threatening stimuli by reducing the output of the amygdala (Phelps et al., 2004; Quirk et al., 2003; Herry et al., 2010; Kalisch et al., 2006).
According to the study report, “participants who frequently reported fear in their dreams had reduced autonomic responses to aversive stimuli during wakefulness, suggesting a better ability to regulate defensive and alerting reactions to threatening signals in those individuals.”
The study excluded a small percentage of participants who reported no dreams during the dream diary recording stage, or, who reported dreaming words, rather than images. Inclusion of these individuals in the results may have affected the findings.
The authors suggest the need for further research into the potential roles of sleep and dreaming in exposure and extinction‐based therapies for affective and anxiety disorders. A potential next step, for stronger evidence of the causal ‘exposure therapy’ theories of fear dreams, would be a study where the type of fear dreamt matches the aversive stimuli introduced – thereby, excluding the possibility that participants have existing resistances to the aversive stimuli.
The notion of sleep and dreams necessarily being a ‘safe’ virtual environment must also be questioned. The study excluded people suffering psychiatric or neurological disorders, with it being suggested that these cases represent ineffective emotional management processing. Fear during sleep, in these cases, does not correlate with reduced fear during wakefulness – and, may correlate with high fear response during wakefulness, including decreased regulatory activity of the mPFC.
Whilst not proving a simple causal relationship, the findings suggest a role played by fear dreaming in effective emotional regulatory processes or affective homeostasis. Alongside existing sleep research, it adds further evidence that sleep is an important tool for management of emotions. Whether dreams can be effectively utilised for treatment of anxiety or affective disorders requires further study, including the testing of specific types of fears.
Stock images in Anna Vanes’ design are credited here.