Learning More: Tonic Immobility

In our new series “Learning More” we will be addressing some different topics that we invite you to learn more about.

Today’s blog post is Part 1 on Tonic Immobility from Britta Koenen.


“I felt paralyzed”: breaking down a sexual assault reaction (Part 1)

Imagine this: you’re hosting a group of friends over for dinner, and the night is winding down. One by one, each of them depart and head home; only one friend remains to help clean up. The two of you banter and laugh while you work until you step away to return something to your bedroom. As you turn to leave, you realize your friend has followed you in and closed the door. That uneasy gut feeling tells you something is off as your adrenaline begins to spike. As they speak and approach you, your heart drops as you realize they intend to take advantage of you. Fear grips you as you struggle to assess what to do. They’re blocking the door, you’re in a corner, no one else is home—you feel trapped. As the assault starts, you try to talk and maneuver away to no avail, when suddenly you’re completely paralyzed. You can see and hear everything that’s happening, but your body is rigid, your voice won’t work, and you can’t feel any pain. The panic you’re feeling escalates as you’re stuck in your mind with no control over your body. There’s a name for this reaction: tonic immobility.


Researchers define tonic immobility as “a temporary catatonic-like state, marked by…motor inhibition, suppressed vocal behavior…[and] attenuated responsiveness to stimulation”1. Simply put, it’s when the brain puts the body into a short period of paralysis to protect it from serious injury or trauma. Oftentimes, this paralysis is accompanied by a host of other characteristics too. These can include the inability to vocalize, the inability to feel pain, tremors or muscle spasms, lowered heart rate, lower body temperature, and slower breathing. 

There are two crucial things to remember about tonic immobility. The first is that you’re fully conscious while it happens. Someone going through this is aware of the traumatic event happening and does fully remember it, often in very vivid, sensory detail. The second is that tonic immobility is involuntary; a person can’t “choose” to not freeze. Our brain has a deep, animal instinct that automatically turns on tonic immobility when the body receives certain danger cues; ultimately, this instinct is meant to protect us from harm. 

So what are these two cues that turn on tonic immobility? The first cue is extreme fear. In humans, tonic immobility can happen during highly traumatic events like sexual assault or rape, war-related trauma, urban violence, car accidents, natural disasters, and more. An individual going through any of these is likely to have extreme fear as the traumatic event is happening. The second cue is either physical restraint or the perception of being trapped. This can mean being held down by a perpetrator during a sexual assault or a seatbelt restraining you after an accident, but it can also mean feeling like there’s no way out of a situation—EVEN without physical contact occurring. This cue is why tonic immobility happens more frequently with sexual trauma than other types of trauma; sexual assault is more likely to have that physical component.

Tonic immobility is sometimes referred to as trauma-induced paralysis, rape-induced paralysis, freezing, or whatever language a survivor uses to describe the reaction they had. Regardless of the terminology used, the main takeaways about tonic immobility are summarized here:

      • Involuntary reaction to trauma
      • Inability to move, vocalize, or feel pain
      • Fully conscious
      • Extreme fear 
      • Physical restraint/feeling trapped

Over the next few days, we’ll learn about tonic immobility in the context of sexual assault, and how we can use this information to be more empathic to survivors. Stay tuned!

ABOUT THE AUTHOR: Britta Koenen is a senior at St. Olaf College studying biology and women’s and gender studies. Her senior project involved researching, writing, and creating educational programs focused on tonic immobility. Contact her at britta.koenen@hotmail.com.