A Perspective on Adversity, Emotional Memory Images and Pre-Sleep Arousal in Sleep Disorders

By Matt Hudson and Dr. Nazish Chaudhary

Abstract 

One of the vital body processes in human beings is sleep. The quality and quantity of sleep have a crucial role to play in a person’s wellbeing. Mental health, cognitive performance, and physiological immunity depend on adequate sleep. People with mental health conditions such as post-traumatic stress disorder (PTSD) and depressive disorders are known to experience emotional memory images (EMIs) of a traumatic event. An overwhelming amount of the global population, however, has suffered adversity, a lesser stress disorder to PTSD, yet still highly prevalent. The common sleep disorders associated with EMIs are insomnia and sleep apnoea. The frequent symptoms range from difficulty falling or staying asleep to difficulty in breathing rhythm during sleep. This complex process is often linked with and mediated by a variety of factors, one of which is pre-sleep hyperarousal. The brain becomes hyper-alert to subconscious perceived potential threats, making it difficult to relax and failing to maintain deep sleep, which may cause frequent awake cycles each night. This article proposesEMIs of adverse life events as a cause for hyperarousal during the pre-sleep phase. Sleep disorders are a serious danger to the physical and mental health of an individual. Thus, clearing EMIs with the therapeutic application of the Split-Second Unlearning (SSU) model may improve psychophysiological health through better sleep quality. This paper has implications for sleep specialists, mental health workers, patients and the non-clinical general population. 

Introduction

An EMI is a nonconscious threat to the system; therefore, cognitive and somatic arousal can be seen as natural responses to this perceived threat. This is akin to vicarious trauma or secondary traumatic stress, where individuals suffer terribly from an imagined trauma. The intricate relationship between sleep problems and stress has long been studied, revealing particular implications for individuals with PTSD (). Adverse childhood experiences (ACEs) is another area of trauma disorder, which has been extensively studied, highlighting how prevalent ACEs are and their far-reaching effect on morbidity and mortality (). This article choses the lens of adversity to view pre-sleep problems and insomnia (for the difference between PTSD and Adversity see ). Emotional states like low mood in depression is also considered widely recurrent adversity related experience following an increasingly stressful global environment, exemplified by the response to the COVID-19 pandemic (). Adverse experiences in life such as an unexpected adverse event, injury or stressful and traumatic situations can form emotional memory images (EMIs) in the mind of an individual. 

Research from Hudson and Johnson (2021) () adds another layer to our understanding by exploring the EMIs that can influence pre-sleep arousal without coming to our conscious awareness, especially in individuals who have experienced multiple adverse life events. The initiation and maintenance of sleep and wakefulness are controlled by built-in neural networks and are influenced by circadian rhythms. Suppression of the hypothalamic-pituitary-adrenal (HPA) axis allows sleep to begin and continue for an adequate amount of time. Alternatively, stimulation of the HPA axis releases glucocorticoids to encourage wakefulness and sleeping interruptions. This article asserts that the human subject when confronted with a nonconscious stressor (an EMI), has a distinct biobehavioural marker, which triggers the neuroendocrine to reroute energy reserves, enabling the subject’s survival (,). Prolonged exposure to adverse circumstances can, however, alter the baseline activity level of the HPA axis, leading to either hyper or hypo-reactivity (). 

Hyperarousal at the onset of sleep is repeatedly associated with the symptoms of insomnia disorder (). Insomnia is one of the most prevalent sleep issues, characterised by elevated levels of adrenocorticotropic hormone (ACTH) and cortisol, which is in line with a state of hyperarousal in the central nervous system ().

When confronted with a real or imagined threat, animals automatically activate the fear defence cascade. This evolutionary response to a threat subconsciously arouses the animal to an alert freeze response. This hypervigilant arousal response can mean the difference between life and death for the animal. After a rapid appraisal of the proposed threat, the active flight or fight response may be prompted. However, if the threat is assessed as more harmful than the capacity to cope, then the hyporarousal state of freeze, faint, tonic immobility, and quiescent immobility will take precedence (). This article proposes that affected individuals who have experienced an adverse or emotionally overwhelming event to an extent that necessitated a hyporarousal freeze response will form and continue to strengthen an emotional memory image (EMI) of the event each time they are triggered with exposure to a similar situation or stimuli. The EMI is stored extracorporeal, outside of the individual’s conscious awareness, becoming more vivid to the subconscious reptilian brain as sleep draws closer. The level of consciousness with respect to hyperarousal response creates a clear distinction between animals and humans. The stress response of an animal after escaping a predator switches off natural stress regulation response while this is not the case in humans. This paper further suggests the purported deregulatory stress that is highlighted in numerous studies, is actually a natural stress response to a nonconscious EMI.

The alteration in the emotional content of the memory is possible during a deep stage of sleep called Rapid Eye Movement (REM). Noticeably the encoding of emotions related to events activates the amygdala region in the brain. Breathing rate increases in wakefulness but this is not the case while asleep. Among the phases of sleep, the non-rapid eye movements (NREM) sleep stage transitions into the REM stage creating changes in respiration ().

Emotional Memory Images and Pre-sleep Arousal 

EMIs have been defined as “Trauma-induced, non-conscious, contiguously formed multimodal mental imagery, which triggers an amnesic, anachronistic, stress response within a split-second”. Affected subjects have recall and flashbacks, however, an EMI creates amnesia leaving no memory of the specific experience ( ,,  for an in-depth view of amnesia see ). Inserting an EMI into the process of pre-sleep arousal fills a gap in the literature. This answers the relationship between stress experienced during the day and the quality of sleep at night. Moreover, both physiological and cognitive forms of pre-sleep arousal have been implicated in further deteriorating sleep in stressful conditions.

Cognitive and Somatic Arousal

Pre-sleep arousal manifests in two categories: cognitive and somatic. Symptoms of cognitive arousal before bedtime often consist of anxiety, persistent thoughts, and a mind that won’t settle. On the other hand, somatic arousal manifests through physical symptoms such as an elevated heart rate, bodily discomfort, and issues with breathing. Both somatic and cognitive forms of pre-sleep hyperarousal have been demonstrated to influence the connection between daytime stress and deteriorating sleep quality ().

Hyperarousal During Pre-sleep Stage

As the biological clock turns and the circadian rhythms ebb towards the pre-sleep stage, the individual relaxes and the HPA axis stands down, allowing for the onset of natural sleep. However, if, as in the animal kingdom, the proximity of the predator is encroaching, then the EMI will trigger the alarm, regulating the fear cascade. When seen as an evolutionary heuristic, the approaching EMI rapidly (within a split-second) prompts the HPA axis to instigate a hyperarousal state. This state of hypervigilance will maintain the individual’s survival in the short term, although, over the longer term, the effects of insomnia can impact morbidity and mortality (). This paper suggests that hyperarousal pre-sleeping is a psychophysiological survival attempt in order to avert close proximity to an emotionally overwhelming past experience. The past experience and all of its connotations are held within the EMI as is the hyporarousal of the freeze response. EMIs are anachronistic, therefore, each time the individual falls asleep they face the original context, enduring the same experience of isolation and censorship, trapped by their captor, unable or unwilling to cry out “Enough!” This paper concludes that the heightened activation of the HPA axis is therefore a natural regulatory stress response to an EMI. The body raises the alarm, working hard to maintain a safe distance between the self (in the present) and the self (within the EMI in the past). The anachronistic nature of the EMI acts as a loyal messenger, seeking to amalgamate a missing piece of the individual’s life puzzle. Yet, each time integration is attempted, the door is firmly locked.

This results in irregular breathing and poor metabolic control. According to the model of Split-Second Unlearning, the original stress response learned in such a short time may lead to a chronic pathology (). This function can also be applied to similar emotionally overwhelming experiences that stir up distress such as grief, following a recently deceased significant other. Emotional components of memories may become a cause for sleep disruption when difficulty in emotional regulation and impaired cognitive functioning happens (). 

According to the existing literature, the most commonly occurring sleep condition as a result of respiratory distress is sleep apnoea. This experience is indicated by short episodes of breathing cessation. Sleep apnoea occurs primarily in three forms: central, obstructive, and complex. Among these, the most prevalent type is obstructive sleep apnoea (OSA). Obstructive form is characterised by the relaxation of muscles that block the airway and completely stop breathing as if a pause has occurred. These disruptions may appear once within an hour (). In such cases, there is no evident cause of the central apnoea and its occurrence is reported less commonly than the obstructive type (). This is a state in which the brain is unable to send proper signals to the muscles to control breathing. 

On the other hand, complex sleep apnoea refers to a type of sleep-disordered breathing characterised by the persistence or emergence of central apnoea (more than 5 episodes per hour). It is not easy to cure this condition despite the resolution of obstructive events through positive airway pressure (PAP) therapy (). Could the presence of an EMI provide greater insight into this distinct area of sleep? Sleep apnoea has been shown to impair the brain and body functioning which poses many risks to mental health; anxiety or depression have been linked to disturbed sleep (). 

Adversity, EMIs and REM Sleep

The Split-Second Unlearning model (SSU) () proposed an individual would have a sharp intake of breath when an EMI is activated, reading the body for the onset of a real or imagined adverse experience. The manifestation and characteristics of diverse maladaptive mental images are observed in illnesses, for example, obsessive-compulsive disorder and dissociative disorders (). This has a neuroanatomical and neurophysiological impact on the individual, which can leave a person feeling unsafe (). When an individual is sleeping, however, a sharp intake of breath as an alarm mechanism is of no use, therefore the authors propose that breathing is momentarily arrested to arouse the dormant individual. The EMI may therefore produce a psychophysiological obstruction to sleep, invoking sleeplessness as the brain is alerted to a predator attack (). Subsequently, this action prevents the EMI from entering the process of memory consolidation. The EMI then returns to its stored position within the mind and the peripersonal space of the individual. An alternate hypothesis may be that the presence of an EMI promulgates greater sleep, so the person remains dormant until the threat has passed; perhaps shedding more light onto the lethargy found in depression, Chronic Fatigue Syndrome (CFS) and Myalgic Encephalomyelitis (M.E). Also, look at Fibromyalgia: Imbalance of Threat and Soothing Systems (FITSS) (Pinto et al., 2023). 

Recurrent sleep disruption is a predictor of severe mental illnesses i.e., thinking and perpetual inaccuracies, negative emotions, and irritable behaviours with other problems (). A study suggested that wakefulness and sleep states might continue activating the stress response unless there is a method to clear emotional memories directly. The therapeutic model SSU clears EMIs to rapidly unlearn the constant firing of the stress response (). The interruption of EMIs may positively influence our mood, thoughts, and actions in daily life, particularly when recalling past experiences or planning for the future. This could enhance the mental health of those who suffer from distressing EMIs and possibly co-occurring sleep disorders. 

According to previous studies, clearance of emotional memories has been trialled with the help of neurological procedures (, ).  In a study to examine the prevention of memory retrieval, researchers observed that neuroimaging indicated suppression of the hippocampus and amygdala activity in the brain. As a result, their effect regulation was enhanced (). 

The SSU model provides a fresh viewpoint on disrupted sleep, which may shed more light on mental and physical health issues. The premise is simple – an EMI is created via a person’s first exposure to an adverse (traumatic) or emotionally overwhelming experience. This paper proposes that informational overwhelm caused by the first-time experience is then amplified within the pre-sleep state, thus disrupting and preventing restorative sleep. 

Novel, Unprecedented, Adverse Conditions Create EMIs

In 2020 the global population encountered a novel, unprecedented coronavirus, and the media around the world relentlessly reported deaths and ramped up fear. The response of Governments was to create a novel, unprecedented response, in the form of wearing facemasks, lockdowns, and self-isolation, all first-time events which have led to a tsunami of harm upon the trusting public. The European Academy for Cognitive-Behavioural Treatment of Insomnia forecast the maltreatment that the responses to curtail the virus would cause (). Currently, their evaluation specific to sleep shows a complicated situation where the pandemic has significantly harmed sleep quality. Additionally, individuals who already have sleep disorders could be more vulnerable to sleep changes triggered by specific aspects of a pandemic (4). Similarly introduced by European Scientific Institute, the exploration of the need for interventions for the post-crisis period has been conducted. This perspective article highlights the impact of adversity on sleep problems irrespective of demographics; therefore, the applicability of the SSU model is vast. 

During sleep, EMIs warn the sleeper to wake up and deal with the experienced threat, even though it is not present in reality. This disrupts sleep and leads to difficulty in maintaining the breathing rhythm, which leads to an OSA (). 

A group of researchers () illustrated that as soon as the human brain enters into the phase of REM sleep, certain characteristics, physiological functions, and clinical features are observed. Eye movements explain this state via the results of an electroencephalograph (EEG) showing mixed amplitude and frequency. Emotional processing of nightmares including enactment, fearful awakenings and frequent respiratory distress also occur at this stage. The sleeper experiences fearful images stored in the memory. As a result, the function is to activate the learned safety behaviours to survive the experienced threat. This is usually seen among patients with PTSD or anxiety-related disorders (). This paper asserts owing to the anachronistic nature of an EMI, the subject faces the EMI at the same point in time that the actual event occurred. This means that the subject continually confronts the mental threat within the same context and with the same internal resources that were present in the first event. This leaves the subject held within an arousal response when they enter REM sleep. 

The results of Nuffield Health’s 2022, ‘Healthier Nation Index’ highlighted that almost 6,000 of the 8,000 participants were getting poorer sleep and 1 out of 10 were surviving on between 2-4 hours of sleep per night (). The COVID-19 pandemic and the countermeasures that were enforced to contain the virus were unprecedented and created worldwide fear. The negative impact of these measures has also created increased stress anxiety and depression (,). This article purports that EMIs may be disturbing sleep owing to the continual adverse conditions of the modern world. As the novelist Charlotte Brontë put it “A ruffled mind makes a restless pillow” (Brontë, 1816-55).

Discussion

Sleep is understood with the two-process model for control of sleep-wake cycles. The circadian clock regulates in a cyclic pattern and homeostasis is maintained. Every 24 hours it repeats. Reticular activating systems and associated neuro-modulatory centres are involved in the promotion of sleep in mammalian brains. GABA inhibits the awakening state and it is followed by suppression of GABAergic pathways for activation and wake cycle whenever it reaches a threshold. Other than region loci, molecular functions are also part of the arousal circuit. The expression of these molecules is also identified to initiate or maintain the sleep-wake cycles. Sleep physiology is the foundation for predicting sleep disruptions and treatment of sleep disorders. Although greatly studied, the mechanism by which memory and sleep function remain unidentified, giving a fertile ground for further research. The biomedical approach is to grasp a sense of metabolic functions among human beings managed via the hypothalamus. 

This perspective paper proposes EMIs created via first-time adverse experiences drive HPA regulation in the pre-sleep stage of the sleep process, leading to insomnia. The removal of EMIs via the SSU process can therefore reduce disruptive sleep. EMIs are stored outside of a person’s conscious awareness through a combination of factors, and they will continue to appear unless there is a system that helps to clear the mind. The clearing takes place through the Split-Second Unlearning model. 

Using SSU, a practitioner scans the subject for a biobehavioural marker, once located the practitioner brings this nonconscious response to the awareness of the subject. The curious state of discovery that the practitioner engages the subject in, merged with new learning of their EMI trigger, causes full memory erasure (). Removing the EMI extinguishes the alert to the reptilian brain, preventing fear in the pre-sleep stage and allowing for continued restorative sleep. The disruption of sleep is a main risk factor that damages overall mental health. Clearing EMIs restores sleep and encourages individuals to maintain adequate physical, neurological, and mental health (). Eye Movement Desensitisation and Reprocessing (EMDR), a psychotherapeutic approach to freeing a person from traumatic memories, points to the revivification of the original scan path that the eye created during the traumatic event (). The subject’s eyes fixate on a certain “order, direction, shape, length and duration” (, ) and this is similar to what the SSU practitioner scans for. 

Conclusion

Professor of neuroscience and psychology, Matthew Walker, has stated:

“Sleep disruption further contributes to all major psychiatric conditions, including depression, anxiety, and suicidality” ()

The present paper proposes a way to identify, target and remove EMIs, which create a disruption during pre-sleep, leading to insomnia. EMIs are discussed in detail to connect them with the development of pathology among children and adults. Throughout a person’s life, stress and adversity are unavoidable. The therapeutic approach of SSU is introduced to remove EMIs from the mind’s eye by targeting the scan path of the eyes as they fixate or avoid these nonconscious stressors. Interrupting the connection between the brain and the EMI works on the principle of SSU. This therapeutic model breaks the informational loop between the EMI and the brain. Once the EMIs are cleared the natural sleep process can proceed. Future studies are recommended to test the efficacy of SSU as an interventional technique to prevent sleep disorders among different populations, with follow-ups or as a longitudinal study. This is applicable in a variety of settings. 

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