Introduction to Flashbacks, Nightmares, and Intrusive Memories


Introduction to Flashbacks, Nightmares, and Intrusive Memories

February 14, 2015

Re-experiencing past trauma is the classic symptom of PTSD and can occur as a nightmare, flashback, or intrusive memory.

The difference between a flashback and an intrusive memory is simple. In a flashback you’re actually reliving the memory, which means you’ve lost touch with your current situation. With intrusive memories, you know where and when you are, but the memory keeps intruding in your mind.

Trauma nightmares are often recurrent, may include details of a past trauma, can be terrifying, and often wake you out of sleep. Sometimes they disrupt sleep so badly that you don’t want to sleep!  Their origins lie both in your trauma and in your high arousal state.

You can also experience severe emotional or physical distress without the actual memory attached. This can lead to misdiagnosis, as it may resemble a panic attack, an episode of acute pain, a seizure, or a cardiac event.

All of the above are examples of a traumatic memory that’s resurfaced and interfering with your daily life.


What are Traumatic Memories?

Traumatic memories are different from normal memories. In normal life, your brain lays down a sequential memory track, kind of like a video but including all the senses. This is managed by the hippocampus, a kind of filing cabinet for locating memories in your brain.

But in a terrifying situation, the brain grabs sequential snapshots, usually combined with very strong emotions, which it then isolates from your normal memory. This process is handled by the amygdala, a part of your brain that controls strong emotions. I like to think of a traumatic memory as an emotional abscess that your brain has carefully walled off.

Traumatic memories are extremely potent. They contain strong negative emotions like terror, rage, shame, and despair, which makes their reappearance in flashbacks and nightmares overwhelming and disturbing.

Trauma memories don’t deteriorate with time. Our normal memories diminish or get lost through the years, but if you activate a traumatic memory, even 50 years after the event, it recurs with the same emotional intensity it held when the trauma just occurred.

Why do our brains do this? I assume it serves some life-preserving function. If you survived the first event, then you can draw on this experience and repeat it whenever a similarly dangerous situation occurs. That’s why reminders of the original situation immediately trigger your old trauma memory.


 What are Triggers?

Triggers are reminders of the trauma, and can evoke the release of traumatic memories. Triggers are everywhere. They can be anything your mind sees as similar to the situation where you were traumatized. They cause your brain to retrieve the trauma memory in a “flash”.

Common triggers include:

  1. Environment: heat, cold, rain, storm, etc.
  2. Senses: smell, hearing, seeing, feeling, pain
  3. Thoughts: about self, about the past, about a similar situation
  4. Emotions: fear, anger, distress, disgust, guilt, shame
  5. Media: news or movies about a similar situation
  6. People associated with the trauma.

Your trigger may be as simple as a smell, a sound, a name, or the temperature outside. It may be a scene in a TV show, or a subject of conversation over dinner. In fact, we all do this with good memories, hear a song or smell a food that reminds us of a pleasant occurrence in our past.

Two-way communication about traumatic triggers is very helpful. If you have PTSD, it’s good to learn and keep a list of your own triggers. That helps you to anticipate problems and understand what’s happening when re-experiencing occurs. If you live around someone with PTSD, it’s good to know his or her triggers. That way you won’t unintentionally upset them.



Exposure Therapy is considered the gold standard. It involves revisiting the traumatic memory until it no longer evokes such strong emotions and physical responses. This utilizes the brain’s ability to become desensitized to a recurring situation. Some people don’t tolerate it well, but if you can complete the process, it does work.

There are a number of different kinds, including:

  • CBT for trauma
  • EMDR
  • Telling your story
  • Rewriting your story (often used with nightmares)
  • Reenacting the trauma
  • Virtual reality programs through the VA
  • Massage or body therapies.

The following Medications can help to disconnect triggers from the trauma memory, or prevent the creation of a new trauma memory if used immediately after trauma:

  • D-cycloserene
  • Propranolol
  • Cannabinoids
  • MDMA

Not usually taken as a daily medicine, they can be used before or immediately following exposure.

Trans-cranial Magnetic Stimulation (TMS) is now available. It involves a strong magnetic field placed near your brain and has been shown to decrease intrusive symptoms.

My next blog will discuss all these treatments in more detail.


Bottom Line:

Memories of severe trauma are stored separately and can return abruptly if you encounter a similar situation. This tendency to trigger can be significantly reduced using exposure therapy (desensitization) alone or with appropriate medications, or taking a series of Trans-cranial Magnetic Stimulation treatments.





kathleen.sales says:

There are two treatments that help nightmares. The first is a medication, prazosin, which blocks the stress chemicals in your brain which lead to nightmares. The second is a technique of rewriting your nightmare. Check out the blog: Treatment for Flashbacks, etc.

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