Sleep is one of the essential biological processes for physical and emotional recovery. However, in people who have experienced trauma, this mechanism can be significantly disrupted. Night terrors, recurring nightmares and sudden awakenings are not isolated episodes, but manifestations of a neurobiological system that keeps processing highly charged information, even while we rest.
These disturbances are closely linked to the functioning of two brain structures that are key to emotional regulation and memory consolidation: the amygdala and the hippocampus. Understanding how they interact during sleep, and how trauma alters their patterns of activity, helps explain why night-time can become a moment of vulnerability for so many people.
1. EXPLAINING THE CONCEPTS (PSYCHOEDUCATION)
To understand trauma and how it relates to disturbances of wakefulness and sleep, we need to understand the relationship between the hippocampus, the amygdala and the traumatic experience.
1. The hippocampus: the memory “library”
The hippocampus is a part of the brain responsible, among other things, for storing memories and placing them in time and space.
Think of it as the librarian who puts memories in order: what happened, when and where.
When a person has an ordinary experience, the hippocampus takes in this information, processes it and stores it in an orderly way.
But if the experience is very intense or traumatic, the hippocampus can become “overloaded” by the level of stress and fails to store the memory properly. That is why traumatic memories tend to be fragmented or extremely vivid, as if they did not belong to the past but were happening all over again.
2. The amygdala: the emotional “alarm”
The amygdala is the part of the brain that acts like an alarm that detects danger.
Its job is to trigger the appropriate emotional and physiological responses to threats: speeding up the heart, releasing adrenaline, preparing the body to flee or fight, and so on.
In traumatic situations, the amygdala becomes hyperactive and is “trained” to react to anything that is reminiscent of the traumatic experience, even when there is no longer any real danger, only a memory. In other words, with trauma, the alarm stays permanently switched on.
3. When the alarm and memory fall out of sync
In trauma, the brain experiences an imbalance between the amygdala and the hippocampus:
• The amygdala records the intense emotion (fear, terror, helplessness).
• The hippocampus fails to file the memory properly.
The result: the traumatic memory is not felt as something in the past, but is relived in the present (which is why, in PTSD – post-traumatic stress disorder – people experience flashbacks, nightmares or disproportionate reactions).
2. WHAT HAPPENS DURING A CRISIS?
The brain works on different “levels”:
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Rational brain (neocortex) → Makes decisions, analyses, plans.
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Emotional brain (limbic system) → Manages emotions and memories (amygdala, hippocampus…).
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When the brain perceives an intense or prolonged threat:
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The amygdala (the emotional alarm) takes control.
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The hippocampus “freezes” (it cannot put the experience in order).
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And the prefrontal cortex – the rational part – temporarily disconnects.
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Instinctive brain (brainstem) → Regulates survival, that is, breathing, reflexes and the fight-or-flight mechanisms.
Under normal conditions, these levels work together: you feel an emotion, recognise it and decide how to act. When the limbic system is activated, the person loses these abilities and may feel confused, disoriented or even unreal.
When the emergency system never rests
In trauma, especially if the experience that caused it was intense or repeated, this alarm system stays switched on even after the danger has passed.
That is when symptoms such as these can appear:
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Flashbacks or intrusive memories: the amygdala fires as if the danger were still present.
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Depersonalisation or confusion: the hippocampus cannot place the memory in the past.
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Intense emotional reactions with no apparent cause: the rational cortex tries to make sense of something it cannot control.
All of this creates a dissociation between thought and emotion.
“I know I’m safe, but my body reacts as if I weren’t.”
6. WHAT TO DO DURING A CRISIS?
First, it is important to be able to regulate the body (turn down the alarm – amygdala). Then we can put the mind in order and bring it back to the present moment (separating what is memory from what is present – hippocampus).
