Fear in dreams and in wakefulness: evidence for day/night affective homeostasis

Abstract

Recent neuroscientific theories have proposed that emotions experienced in dreams contribute to the resolution of emotional distress and preparation for future affective reactions. We addressed one emerging prediction, namely that experiencing fear in dreams is associated with more adapted responses to threatening signals during wakefulness. Using a stepwise approach across two studies, we identified brain regions activated when experiencing fear in dreams and showed that frightening dreams modulated the response of these same regions to threatening stimuli during wakefulness. Specifically, in Study 1, we performed serial awakenings in 18 participants recorded throughout the night with highdensity EEG and asked them whether they experienced any fear in their dreams. Insula and midcingulate cortex activity increased for dreams containing fear. In Study 2, we tested 89 participants and found that those reporting higher incidence of fear in their dreams showed reduced emotional arousal and fMRI response to fear-eliciting stimuli in the insula, amygdala and midcingulate cortex, while awake. Consistent with better emotion regulation processes, the same participants displayed increased medial prefrontal cortex activity. These findings support that emotions in dreams and wakefulness engage similar neural substrates, and substantiate a link between emotional processes occurring during sleep and emotional brain functions during wakefulness. SIGNIFICANT STATEMENTHighly debated while pivotal to current theoretical models of dreaming, the relationship between emotion processing during wakefulness and in dreams remains elusive. In a first study, we used high-density EEG recordings and observed that regions involved in fear processing (i.e. the insula and midcingulate cortex) were activated during fear-related dreams. This first finding demonstrates that emotions in dreams engage similar neural circuits as during wakefulness. In a second study, using fMRI, we show that higher incidence of fear in dreams was associated with reduced emotional arousal and brain responses indicative of better emotion regulation during wakefulness. Together, these results strongly support the idea that experiencing fear in a secure environment, as in dreams, relates to more adapted responses to threatening events in real life. 2000), others reported a balance of positive and negative emotions (Schredl M and E Doll 1998), or found that joy and emotions related to approach behaviors may prevail (Fosse R et al. 2001;Malcolm-Smith S et al. 2012). When performing a lexicostatistical analysis of large datasets of dream reports, a clear dissociation between dreams containing basic, mostly fear-related, emotions and those with other more social emotions (e.g. embarrassment, excitement, frustration) was found, highlighting distinct affective modes operating during dreaming, with fear in dreams representing a prevalent and biologically-relevant emotional category (Revonsuo A 2000;Schwartz S 2004). Thus, if fear-containing dreams serve an emotion regulation f...

EEG microstates of dreams

“…The main goal of this study was to determine whether there exist distinct transient brain states of the sleeping brain that may play a critical role in experiencing and remembering dreams during NREM sleep. A couple of previous studies suggested different brain regions and frequency modulations to be associated with the conscious experience during NREM sleep 13 , 16 , 17 , 26 – 28 . By using the EEG microstate approach, which identifies brain states by the spatial properties, rather than the spectral content of the EEG, we were able to identify and precisely time two microstates that dominate during sleep as compared to awake, and found that these two states dissociated the EEG during dreaming and no dreaming: microstate 3 was more present when participants reported their dreams, while microstate 4 dominated when no dreams were reported.…”

Relationships between Dream and Previous Wake Emotions Assessed through the Italian Modified Differential Emotions Scale

“…Another intriguing, complementary, hypothesis that comes to mind when looking at the general pattern of data is the existence of some sort of “day/night affective homeostasis” (an idea already suggested by [ 75 ]), with the dreaming experience of negative emotions balancing the prevalent expression of positive affect during wake time.…”

The Functional Role of Dreaming in Emotional Processes

“…According to the idea that DE play a role in the emotional processing, more recently awake fMRI measures revealed that subjects experiencing frequent fear during DE have a higher activation of mPFC and reduced activation in the insula, amygdala and midcingulate cortex when faced with aversive stimuli (Sterpenich et al, 2019 ). The results are consistent with the view that mPFC should exert an inhibitory control on fear expression by reducing amygdala activity (Phelps et al, 2004 ).…”