Sleep

Terror Management Theory (TMT) and REM Sleep

We can observe anxiety-buffering mechanisms in real time during dreams.

Posted Jul 05, 2020

TMT argues that human beings, uniquely among the animals have a kind of awareness of death that could be psychically paralyzing if that awareness was allowed to intrude into our daily thoughts (Greenberg, Pyszczynski, & Solomon, 1991; Solomon, Sheldon, Greenberg, J. & Pyszczynski, T. (1991) "A terror management theory of social behavior: The psychological functions of esteem and cultural worldviews", in M. P. Zanna (Ed.) Advances in Experimental Social Psychology, Volume 24, Academic Press, pp. 93–159 ).

The idea is that there is a terror associated with the experience of death-associated ego dissolution or annihilation that causes human beings to erect all kinds of psychic defenses to ward off the terror. Some TMT theorists argue that culture itself acts as a defense or buffer against the anxiety that implicit death awareness causes.

We attempt to anesthetize the awareness-of-death-induced anxiety with tried-and-true strategies of boosting the ego (building up self-esteem), investing in meaningful interpersonal relationships, and erecting cultural world-view systems like religion or philosophical theories. When all these fail or are unavailable, we turn to addictions to drown that self-awareness as much as we can in some kind of oblivion.

While at first glance, none of this sounds entirely plausible—for example, I invest in relationships because I love or value these people, I adhere to a cultural world view because it appears to me to be true and I boost my ego only moderately if at all—yet, TMT backs up its claims with literally hundreds of experiments. Many of these experiments use clever ways to remind people of the possibility of death.

These are called mortality salience (MS) manipulations. For example, they may ask participants to simply write out a narrative of what their death would look like and then test them on defenses against death awareness. When people are exposed to these sorts of MS manipulations, they inevitably engage in behaviors designed to boost their egos, vociferously defend their cultural worldviews (often their religious views) and they wax sentimental about their close relationships.

Decades of work within the TMT paradigm have suggested that when thoughts of death and its associated anxiety are in conscious awareness, a set of proximal defenses involving death thought suppression emerges, which basically attempt to get rid of thoughts of death altogether. But even when death thoughts are out of conscious awareness, a second set of distal defenses kick in to mop up whatever lingering sentiments of death anxiety remain. These distal defenses proceed unconsciously (I will suggest below perhaps in dreams) and include the development of cultural worldview adherence (for example, development of a religious worldview), self-esteem enhancement, and increased commitment to meaningful interpersonal relationships. Working together, these defenses help the individual overcome the overwhelming and acute death anxiety that would otherwise compromise their ability to function in society.

Anxiety Buffering Defense Theory; ABDT is a recent development of TMT to explain the onset and maintenance of post-traumatic stress disorder (PTSD). It posits that anxiety syndromes like PTSD result from a disruption in one's death anxiety-buffering mechanisms. The disruption of these mechanisms leaves the individual defenseless in the face of overwhelming anxiety, which in turn leads to the major symptom clusters of PTSD. 

Support for ABDT comes from studies that demonstrate that individuals with PTSD do not respond to mortality salience reminders (e.g. death primes) in the defensive ways (i.e. boosting attachment to one's cultural-religious worldview, one's self-esteem or interpersonal attachment targets) that psychologically healthier individuals do.

Despite the growing body of evidence supporting some of the TMT/ABDT's central propositions the mechanisms of anxiety-buffer disruption remain unclear. Without directly clarifying the different neurocognitive mechanisms of anxiety buffer disruption, it is difficult to know what should be addressed in TMT/ABDT-based clinical treatment proposals for anxiety syndromes and PTSD.  

I suggest that the neurocognitive mechanisms of anxiety buffer function after mortality salience increases is REM sleep-dependent emotional memory consolidation processes; and conversely, disruption or breakdown in buffering mechanisms is the breakdown of the normal REM sleep-dependent emotional memory consolidation process that handles all fear-related memories. Normally when these REM-dependent memory consolidation processes break down due to sleep deprivation of sleep disorder one gets disturbing dreams and nightmares and daytime distress. But there is evidence also that self-esteem suffers and maintaining cultural worldviews becomes difficult as well.

A fear memory circuit is normally and preferentially activated during REM. Indeed, many sleep scientists now see REM as a functional system designed to integrate threat, fear, trauma, terror into long term memory systems so that the individual can learn from these experiences and not be paralyzed by these negative events and emotions.

Structures in the fear memory circuit overlap to a significant extent with structures that are activated after mortality salience (i.e. threat) manipulations. Specifically, these structures include the amygdala, hippocampus, insula, ventromedial prefrontal cortex, among other structures.

It is generally agreed that the key structures involved in the consolidation of fear memory include the hippocampus, the insula, the central and basolateral nucleus, the bed nucleus of the stria terminalis of the amygdala (Ce, BLA, BST), and the ventromedial prefrontal cortex (vmPFC)—all activated (via theta coupling) during REM. The vmPFC appears to facilitate depotentiation of amygdala reactivity via inhibition of brainstem-projecting central nucleus of amygdala referents. Synchronized amygdalohippocampal and medial-prefrontal activity during REM sleep correlates with individual differences in consolidation efficacy, supporting a role for theta oscillations among limbic system structures in sleep-dependent consolidation processes. Neuroimaging studies of patients with nightmares associated with post-traumatic stress disorder (PTSD) show reduced vmPFC activity/volume and amygdala hyper-responsivity.

The benefits of identifying TMT-based anxiety buffering mechanisms with REM sleep-dependent emotional memory consolidation mechanisms is that a great deal is now known about REM sleep neuro-cognitive processes and mechanisms. By looking at REM sleep and dreams after morality salience manipulations one might be able to observe, in real time, construction of cognitive buffering and thus be able to target these mechanisms in treatments for PTSD and nightmares.