What Happens During a PTSD Flashback?

What Happens During a PTSD Flashback?

A flashback is an intrusive, unintentional, vivid memory of a traumatic event. Flashbacks are one symptom of post-traumatic stress disorder (PTSD).

Defining PTSD

Post-traumatic stress disorder (PTSD) occurs in the aftermath of a traumatic event, including military conflict, assault, interpersonal violence, a car accident, or a natural disaster. PTSD can also occur among first responders, as well as people whose loved one experienced a traumatic event.

To be diagnosed with PTSD, an individual must experience symptoms in the following four categories for at least a month after the trauma:

  1. Re-experiencing the event. People suffering from PTSD often re-experience the event in unwanted, unintentional ways, including flashbacks and nightmares.
  2. Avoidance of the event. Someone who is experiencing PTSD will often try to avoid reminders of the event.
  3. Negative thoughts or emotions. The person may experience negative emotions (or a lack of positive emotions), feel self-blame, or lose interest in activities they previously enjoyed.
  4. Hypervigilance. PTSD patients typically feel as thought they are constantly on “high alert.” They may have trouble sleeping, be irritable, or become easily startled, for example.

While many people may develop some of these symptoms immediately after a traumatic event, not everyone who experiences a trauma develops PTSD.

What a PTSD Flashback Feels Like

Flashbacks can be incredibly vivid and involve re-experiencing the sights, sounds, and smells that were present during the traumatic event. Some people become flooded with the emotions that they felt at the time of the trauma. Flashbacks can be so overwhelming and immersive that the person experiencing the flashback may temporarily feel that they have physically returned to the moment of the traumatic event. In some cases, a person experiencing a flashback may behave as though they were back in the traumatic event.

Flashbacks can occur as a result of a trigger-that is, when they notice something in the environment that reminds them of the traumatic event. However, people can also experience a flashback without being aware of a particular trigger that caused it.

Flashbacks vs. Memories

Flashbacks occur when individuals involuntarily re-experience a memory of a traumatic event. Importantly, the psychological definition of a flashback differs from the common colloquial use of the term. A flashback is not simply a “bad memory." Rather, it is an experience in which an individual actually feels as if they are re-living parts of the traumatic event.

Flashbacks in PTSD are different from intentional memories because they occur without the person trying to do anything to bring back the memory. In fact, psychologist Matthew Whalley and his colleagues have found that patterns of brain activation are different when people are exposed to words that they associate with flashbacks, compared to words that they associate with non-flashback memories.

Studies on PTSD Flashbacks

Psychologists have investigated whether it is possible to prevent the development of flashbacks after a traumatic event. Researcher Emily Holmes and her colleagues have suggested that, since flashbacks are often powerful visual images, it may be possible to reduce the severity by "distracting" the visual system.

To test this idea out, Holmes and her colleagues conducted an experiment in which participants watched a potentially traumatizing video. Afterwards, some participants played Tetris, and others did not. The researchers found that participants who played Tetris only had about half as many flashbacks as the participants who didn't. In other words, it appears that a neutral activity such as Tetris kept the visual systems in the participants' brains occupied, making flashback images less likely to occur.

In another paper by Dr. Holmes' team, researchers asked emergency room patients who had experienced a traumatic event to participate in a similar study. Some participants played Tetris while others did not, and the researchers found that participants who played Tetris had fewer intrusive memories of their traumatic event over the next week.

More broadly, researchers have found that psychotherapy and medication can reduce the severity of PTSD symptoms, including flashbacks. One type of therapy, Prolonged Exposure, involves discussing the traumatic event in a safe, therapeutic setting. Another therapeutic technique, Cognitive Processing Therapy, involves working with a therapist to change one's beliefs about the traumatic event. Researchers have found that both types of therapy are able to lessen the severity of PTSD symptoms.

PTSD Flashbacks Key Takeaways

  • Post-traumatic stress disorder is a mental health condition that can occur in the aftermath of a traumatic event.
  • Flashbacks are a PTSD symptom that involve re-experiencing memories of the traumatic event.
  • PTSD flashbacks can be extremely vivid and may make individuals feel as though they are re-living the traumatic event.
  • Several treatments are currently available for PTSD, and new research is investigating whether PTSD flashbacks can be prevented.


  • Brewin, Chris R. “Re-experiencing Traumatic Events in PTSD: New Avenues in Research on Intrusive Memories and Flashbacks.” European Journal of Psychotraumatology 6.1 (2015): 27180. //
  • Friedman, Matthew J. “PTSD History and Overview.” U.S. Department of Veterans Affairs: National Center for PTSD (2016, Feb. 23). //
  • Hammond, Claudia. “PTSD: Do Most People Get It After Terrifying Incidents?” BBC Future (2014, Dec. 1). //
  • Holmes, Emily A., James, E.L., Coode-Bate, T., & Deeprose, C. “Can Playing the Computer Game 'Tetris' Reduce the Build-up of Flashbacks for Trauma? A Proposal from Cognitive Science.” PloS One 4.1 (2009): e4153. //
  • Iyadurai, Lalitha, et al. "Preventing Intrusive Memories After Trauma Via a Brief Intervention Involving Tetris Computer Game Play in the Emergency Department: A Proof-of-Concept Randomized Controlled Trial." Molecular Psychiatry 23 (2018): 674-682. //
  • Norman, Sonya, Hamblen, J., Schnurr, P.P., Eftekhari, A. “Overview of Psychotherapy for PTSD.” U.S. Department of Veterans Affairs: National Center for PTSD (2018, Mar. 2). //
  • “PTSD and DSM-5.” U.S. Department of Veterans Affairs: National Center for PTSD (2018, Feb. 22). //
  • Whalley, M. G., Kroes, M. C., Huntley, Z., Rugg, M. D., Davis, S. W., & Brewin, C. R. (2013). An fMRI Investigation of Posttraumatic Flashbacks. Brain and Cognition, 81(1), 151-159. //
  • “What Is Posttraumatic Stress Disorder?” American Psychiatric Association (2017, Jan.). //

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