Many people with the lived or living experience of complex trauma have sudden memories, strong emotions, or physical reactions when something reminds them of past events. These experiences are often set off by cues called triggers and may be experienced as flashbacks.
Flashbacks can feel very real and distressing. People may feel as though they are reliving past experiences rather than remembering them.
Understanding how these responses work can help make them feel less confusing.
The brain’s threat system
The brain has systems designed to detect danger and keep us safe. When a threat is perceived, the body may activate survival responses such as fight, flight or freeze.
During traumatic events, these threat-response systems become highly active. At the same time, brain systems involved in organising experiences into coherent narrative memories may function differently.
As a result, traumatic experiences may sometimes be stored in ways that are strongly linked to sensory impressions, emotions and bodily reactions.
How triggers work
After trauma, certain cues can activate memory networks associated with the traumatic experience. These cues are known as triggers.
Triggers can include:
- sounds
- smells
- particular places
- physical sensations
- interpersonal situations
- emotions that resemble past experiences.
Sometimes everyday experiences or sensations can trigger these reactions, which can make flashbacks feel confusing or unpredictable. Flashbacks do not always occur only when someone feels distressed. They can sometimes occur even when a person is feeling calm or safe. This can happen because the brain’s threat-detection systems respond automatically to reminders of past experiences, even when the person is not consciously aware of the trigger.
When a trigger activates these memory networks, the brain’s threat-warning system may respond automatically. Even if the current situation is safe, the brain may briefly react as if danger is present.
Different ways flashbacks may be experienced
Flashbacks can occur in different ways. Not all flashbacks involve clear visual memories.
People may experience:
- Sensory flashbacks – vivid images or sensory impressions connected to past events
- Emotional flashbacks – sudden waves of fear, shame, panic or distress without a clear memory
- Somatic (body) flashbacks – physical sensations such as pain, tension, nausea or changes in breathing
- Cognitive flashbacks – intrusive thoughts or memories related to past experiences.
During a flashback, it can sometimes be difficult to recognise that the experience is a memory rather than something happening in the present. This is because the brain’s threat-response systems are highly activated, while systems involved in reasoning and orientation to the present may be less active.
Although flashbacks can feel immediate and overwhelming, they reflect memory networks being activated rather than current danger.
Emotional flashbacks
Some people experience emotional flashbacks, which involve intense emotional states connected to past trauma rather than clear memories of events.
During an emotional flashback, a person may suddenly feel overwhelming emotions such as fear, shame, sadness or helplessness without immediately understanding why. These reactions may be triggered by situations that resemble aspects of past experiences.
Unlike visual or sensory flashbacks, emotional flashbacks may not involve images or detailed memories. Instead, the person may experience strong emotional states that reflect how the brain and nervous system responded during earlier traumatic events.
Emotional flashbacks can be confusing because they may feel as though the emotions belong entirely to the present situation. Understanding that these reactions may reflect past trauma responses can help people respond to them with greater awareness and self-compassion.
Grounding, orientation to the present, and trauma-informed support can help reduce the intensity of emotional flashbacks over time.
The body and memory
Trauma memories often involve emotional and sensory memory systems that can influence bodily reactions.
This is why survivors sometimes say:
- “My body reacts before I understand why.”
- “Something small suddenly reminds me of the past.”
These reactions reflect how the brain stores and responds to experiences of danger.
Early warning signs of a flashback
Flashbacks often develop gradually rather than appearing suddenly. Many people notice early changes in their thoughts, emotions or body before a flashback becomes intense.
Learning to recognise these early signals can make it easier to respond before the experience becomes overwhelming.
Early warning signs may include:
- feeling suddenly tense, anxious or unsafe
- difficulty concentrating or feeling distracted
- strong emotional reactions that seem out of proportion to the situation
- changes in breathing, heart rate or muscle tension
- feeling disconnected from the present moment
- sensing that something familiar or threatening is about to happen.
These reactions can occur when the brain’s threat system detects reminders of past danger.
Noticing early warning signs can allow people to use grounding strategies sooner and reconnect with the present before the flashback intensifies.
Bringing the brain back to the present
Because flashbacks activate the brain’s threat systems, it can be difficult to think clearly or logically while they are occurring. One of the most helpful first steps is recognising that a flashback is occurring.
Strategies that help re-orient the mind and body to the present can reduce the intensity of these experiences.
These may include:
- Grounding – noticing the present environment through the senses
- Orientating – reminding yourself of the date, your age and where you are
- Self-talk – gently reminding yourself that the experience is a memory
- Movement or sensory awareness – helping the body reconnect with the present moment.
These strategies can help the brain recognise that the danger belongs to the past rather than the present.
What may help during a flashback
Flashbacks can feel overwhelming, but there are strategies that may help bring attention back to the present.
Grounding through the senses
Notice what is around you right now. Look for objects in the room, listen to nearby sounds, or touch something with a distinct texture. Using the senses can help reconnect the mind with the present environment.
Orientating to the present
Remind yourself where you are and when you are.
For example:
“I am safe right now.”
“It is 2026.”
“I am in my home/office.”
Gentle self-talk
Reminding yourself that the experience is a memory can sometimes reduce distress. For example:
- “This is a memory.”
- “This is a flashback.”
- “The danger is in the past.”
- “I am safe now.”
Movement and breathing
Slow breathing, stretching, or pressing your feet firmly into the ground can help the body reconnect with the present moment.
Seeking support
If flashbacks feel overwhelming, reaching out to a trusted person or trauma-informed professional may help.
Different strategies work for different people. Finding what works best may take time and practice.
Support and understanding
Flashbacks and strong trauma reactions can feel frightening or exhausting. Many survivors worry that these experiences mean something is wrong with them.
In reality, these responses reflect the ways the brain and nervous system adapt to overwhelming experiences. Being triggered or having flashbacks is not a sign of weakness and is not the survivor’s fault.
Learning about trauma and memory can help survivors understand these reactions with greater self-compassion. Trauma-informed therapy and support can also help people develop strategies to manage triggers and feel safer in the present.
Key message
Flashbacks occur when memory networks associated with past trauma are activated by reminders in the present.
Although these experiences can feel very real, they reflect memory and threat-response systems being activated by reminders of past danger.
Understanding how trauma affects memory can help survivors make sense of these experiences and support responses that promote safety, grounding and recovery.
