Trauma refers to life-threatening events that overwhelm the nervous system. The overwhelmed nervous system becomes dysregulated by ongoing continuous autonomic nervous system activity. This hyperactivation of the sympathetic or parasympathetic arms of the ANS is marked by intense sensory memories: for example, the sound of squealing tires before a crash, the image of rage on a parents face before being hit, or other smells and physical bodily sensations. A dysregulated ANS can trigger at least a dozen different sleep disorders (see chapter 1 of Putting Trauma to Sleep).
Nightmares are a common response emerging right after trauma. These can disrupt sleep long after the initial event. Research shows that up to 70% of trauma survivors continue to experience nightmares.
· Nightmares range in intensity from vivid replays of the trauma (e.g. a flashback of the sound of cars crashing) to symbolic dreams that reflect differing images of the underlying overwhelming danger (running to escape a bomb exploding).
· These nightmares are so real they can create a fear of sleep and worsening insomnia.
· This fear stems from a sense of losing control when falling asleep. This fear triggers continuous hyperarousal — a state of heightened alertness linked to continuous alarm activation by the locus coeruleus (LC).
· The LC releases the neurotransmitter norepinephrine (NE). The continuous, tonic activation of LC-NE keeps the entire brain in full alert throughout the night, preventing restful sleep.
· When REM sleep does occur, it is swamped by the intense images of the trauma, often with accompanying terrifying feelings of being annihilated, and awakening with heart pounding from how real the terror felt.
· Therapists can assess the impact of trauma by asking about nightmares and using tools like the Nightmare Disorder Index to understand their frequency and severity.
· Treating these disruptive dreams is key to restoring restful sleep. See chapter 8 in Putting Trauma to Sleep for more information on assessing and treating nightmares and intrusive experiences.