Does more stress resolve a disordered stress response?
The late George Carlin provided an apt description of the origins post-traumatic stress disorder (PTSD) in one of his 1980's stand-up routines that has been republished on YouTube.
There's a condition in combat... it's when a fighting person's nervous system has been stretched to its absolute maximum. It's either snapped, or it's about to snap. In the first World War, that condition was called 'shell shock.' - comedian George Carlin (1937-2008).
Carlin explains that the phrase "post-traumatic stress disorder" was invented during the Vietnam War to distance society from the severity of the condition.
Since the 1970's we've learned a great deal more, including the fact that PTSD doesn't just happen to soldiers. It can happen to anyone who experiences an extreme, unresolved stress event.
In the book In An Unspoken Voice: How the Body Releases Trauma and Restores Goodness (2010) renowned psychologist Peter Levine, PhD reframes PTSD as neither a disease nor a disorder. He describes PTSD as an injury -- a description that may encourage trauma survivors to pursue healing of their wounds.
The question is, "How?"
The origins of PTSD
PTSD can occur when stress overwhelms the capacity to respond. Children are especially vulnerable (Carr 2023) because their capacity to respond it lower. Because not every extreme stress situation results in traumatic injury, Levine sought to identify patterns that might predict when stress will be successfully resolved, and when it might lead to longer-term trauma-related disorders.
He discovered two factors that greatly increased the odds of traumatic injury under stress:
powerlessness, and
immobilization.
It is no coincidence that these correspond to autonomic fight or flight responses to threats. Powerlessness frustrates the hormonal and vascular changes that are preparing the human body to fight when attacked. Immobilization frustrates the instinct to flee. Author Gavin de Becker (The Gift of Fear 1996) writes that victims who fight back or flee are less likely to experience PTSD-related symptoms after assault. In the fighting or the fleeing, the victims are exercising agency that gives their somatic, adrenal response an outlet, and it seems to offer some psychological protection. Stripping the victim of the choices their bodies are biologically preparing them for creates a discordance between the sympathetic nervous system activation and the reality of their experience.
Hence, their unresolved stress can manifest as trauma.
While de Becker's explanation is sensible and satisfying, Levine goes even deeper. In his foreward he describes being run over by a car.
Although he remained conscious, he had no motor control of his injured body. He was immobilized, but because he could still speak, Levine was not powerless.
For example, an off-duty paramedic witnessed the crash and rushed to Levine, peppering him with questions. The aggressive tone in the man's voice contributed to Levine's confusion.
He told the paramedic "Please back off," and the man did.
Levine lay on the asphalt, trembling, trying to make sense of what had happened, until he heard the ambulance arrive.
I see the emergency team slip a collar onto my neck and then they cautiously slide me on to a board... . The ambulance paramedic takes my blood pressure and records my EKG... . She fiddles with the equipment and then indicates that it might be a false reading... . My heart rate is 74 and my blood pressure is 127/70. "Thank you," I say. "Thank God I won't be getting PTSD." - Peter Levine, PhD
How does Levine know he won't be suffering long-lasting ill-effects from unresolved trauma?
Because he allowed his body to tremble in response to his trauma, and as a consequence, his pulse and his blood pressure returned to normal levels. The trembling released his body from the fight or flight mode of being attacked by the car.
Although Levine could not run, or fight, the autonomic shaking of his limbs allowed his body to express its natural adrenal response and release the stress that otherwise would have nowhere to go.
When he explained that to his ambulance nurse, she asked him:
"I've noticed that they often purposely stop people from shaking when we get them to the hospital. Sometimes they strap them down tight and give them a shot of Valium. Maybe that's not so good?" "No, it's not," I answered. "It may give them temporary relief, but it just keeps them frozen and stuck." She asked, "You were, it seemed to me, just shaking. Is that what brought your heart rate and blood pressure down?" "Yes," - Peter Levine, PhD
Somatic routes to recovery
Trembling, shaking, tremoring, and shivering are all phenomena that help release the energy being generated when the sympathetic nervous system is in fight or flight activation. However, when these big muscle movements are physically impossible, trembling becomes a viable way to avoid the immobilization that will increase risk of PTSD.
The same phenomenon is often found in patients recovering from surgery. "Perioperative shivering" was once thought to be a thermoregulatory response in patients who entered a hypothermic state during or after surgery. However, there were irreconcilable problems with that hypothesis (Witte & Sessler 2002) and new hypotheses related to the stress and trauma of the surgery have been posited.
For example, patients undergoing brain surgery will often experience a post-operative trembling or shivering -- even when kept warm. In this case, their shivering is unrelated to thermogenesis. Rather, it is a natural response to the trauma of the surgery called post-traumatic tremors.
In one case, a 48-year-old Australian man experienced PTSD resulting from a 2009 car crash that resulted in a six-day coma and required facial reconstructive surgery. Doctors trained the patient to self-administer a trembling intervention that "involved learning to activate spontaneous movements, including shakes and tremors in a safe, controlled and self-regulated way through guided group practice twice daily" (Beattie 2019).
The trembling therapy resulted in extraordinary improvements in the patient's self-reported pain, anxiety, negative thoughts, and ability to cope. The study authors concluded that "the suppression of spontaneous movements including shakes and tremors may be inadvertently increasing the risk of PTSD."
Resolving PTSD
The post-traumatic stress response is characterized by spontaneous and often unpredictable flashbacks to the moment or circumstances of the trauma. Although victims often suffer from the shame of being unable to control their own thoughts, what most people don't realize is that human beings are biologically hard-wired to relive unresolved trauma seeking a position of control. This biological imprinting is so strong, it can even be coded into the expression of our genome and passed down to our children (Seager 2020).
Despite our suffering, there are important evolutionary advantages to being encoded for this compulsion to repeat.
Repetition of the experience in our imagination might provide two evolutionary adaptive advantages:
It allows us to experiment in our minds with new resolutions or stress responses resulting from “What if… ?” creative problem-solving, and
It may reinforce fear-based behavioral adaptations that strengthen automatic threat-avoidance reactions.
Imaginative re-experiencing as a way of exploring alternate outcomes sometimes takes place in therapeutic settings. The risk in any re-experiencing is re-traumatization without resolution -- reinforcing disordered patterns. Nonetheless, according to exposure therapy theory, a gradual re-experiencing of the traumatic event in talk therapy, through journaling, or even virtual reality, will eventually desensitize the sufferer to memories and improve their emotional processing skills (e.g., Powers et al. 2010, Lely et al. 2018).
In human children and in animals, we're more likely to see imaginative re-experiencing of trauma in play than in therapy. Levine describes this phenomena in his book Trauma and Memory (2015), in which he includes this description of three cheetah cubs who survived a lion attack:
In Levine's example, exploring different options and responses in play allows the cubs to resolve the life-threatening trauma of the attack by gaining control of the experience. Empowered by their new self-defense skills, they no longer fear a repetition of the traumatic attack.
Although the cubs will retain the memory of the attack, they will have released the negative emotions associated with that memory, because in the successful reliving of the trauma they will have gained confidence that they can handle the threat.
In this respect, human children work in the same way that cheetah cubs do. For example, in Playful Parenting (Cohen 2002) Lawrence Cohen, PhD describes how a toddler might respond to the trauma of a visit to the doctor’s office for shots.
A three-year-old gets a shot at the doctor’s office. She comes home, and what game does she want to play? Doctor, of course. And who does she want to be? The doctor or nurse—definitely not the patient. And who does she want to to give (the shot) to? Well, her first choice is a parent or another adult. If no one is available, she might use a stuffed animal or doll. And how does she want the game to go? She wants you to pretend to howl and say, “No, no, no please don’t give me a shot. I hate shots! No, no, no,” and act as if you are in agony of pain and terror. This response lets the child be in the more powerful position. It is a simple game of role reversal, but it is very satisfactory… . The play shot might be pretend, but the need for emotional recovery is real. The child chooses this fantasy game because she wants a hand with her genuine feelings about the actual shot. This isn’t just play for fun… . The purpose is to go through the incident again, but this time letting the scary feelings out. That’s why a child likes to play this kind of game over and over and over. - Lawrence Cohen, PhD
Reliving the experience in play rearranges the meaning of the story and those rearrangements have profound consequences. They change our emotions, our identities, our capabilities, and our prospects. They change our perceptions, our beliefs, and consequently they change the biochemistry of our bodies.
The ice bath changed my life. The freezing temperatures helped heal my PTSD in ways no other therapy touched. I needed to reach Fight or Flight and choose my breath and my healing to change the way my brain and body reacted to stress and triggers. - Anna McNally, Inside Sales Rep, Morozko Forge
Stress treats stress?
The counter-intuitive realization of exposure therapy, and related techniques like stress inoculation training (Meichebaum 2017), is that the key to resolving PTSD is titration of trauma by incremental, additional, and repeated re-experiencing of the stressful events.
The underlying biochemical basis for this approach may be related to cortisol.
The popular understanding of cortisol is that temporary, elevated levels in response to acute stressors are a normal and healthy reaction to stress, but that chronically elevated cortisol levels are associated with adverse health outcomes including obesity, inflammation, and depression. However, some studies show that cortisol can be chronically too low in PTSD patients, and that dosing with pharmaceutical cortisol prior to stress exposure can speed resolution of trauma (Yehuda & Golier 2009). Moreover, military veterans with higher levels of cortisol before and after exposure treatments for PTSD received greater benefit from the treatment (van Gelderen 2020).
Given that cold exposure is a validated instrument of psychological stress testing, an ice bath may be an effective mechanism for stress inoculation. For example, previous cold pressor studies have demonstrated a cortisol boost from immersion of one hand in ice water during the cold pressor test (Schoffs et al 2009). Another measured elevated blood serum cortisol resulting from cold water immersion of human subjects (see Figure).
We found that short-term whole-body cold water immersion produced a stressful physiological reaction, which was manifested as hyperventilation, increased muscle shivering, increased metabolism, and increased heart rate. In addition to these stressful physiological responses, cold water immersion induced the marked release of the stress hormones epinephrine, norepinephrine, and cortisol. - Eimonte et al. 2021 (emphasis added)
Another study performed autopsies on hypothermia victims and found elevated blood serum cortisol levels (Shida et al. 2020).
However, other studies are less definitive. A longer-term study in Finland looked at the effects of 20 seconds of winter swimming at 1C three times weekly. After four weeks, subjects showed reductions in cortisol that persisted for the remainder of the 12-week study period (Leppäluoto et al. 2008). Meanwhile, researchers in the Czech Republic studied 10 young men immersed in 14C (57F) baths for one hour, and they also measured a reduction in cortisol levels that exceeded reductions achieved while immersed in warmer baths (Šrámek et al. 2000).
It's not possible to make reliable inferences from these studies, given the different temperatures and exposure times. For example, the study of Czech men is peculiar, because the cortisol levels prior to cold water immersion were nearly twice the levels measured in groups prior to warm water immersion. This anomaly casts some doubt on the reproducibility of the experiment.
Nonetheless, a new study of Lithuanian men in their twenties might clarify some of the confusion. 17 participants enrolled in a randomized cross-over study of short (10 min) and long (170 min) term whole body immersion at 14C, compared to 24C controls. The results showed that both short- and long-term whole-body, cold-water immersion groups measured blood cortisol levels in the low 400's (mmol/L) for several hours after a morning plunge, which is about where they started that day. Studies of diurnal fluctuations of cortisol consistently show that levels are highest in the morning hours, so the cold treatment didn’t boost cortisol as much as it maintained the morning highs. By contrast, the control group in thermoneutral water experienced a reduction in cortisol levels over a comparable period that was consistent with normal diurnal rhythms (Eimonte et al 2022).
What’s really interesting about the Lithuanian results is that the subjects who measured the highest pre-immersion cortisol levels weren’t boosted by the cold bath at all. They didn’t experience the normal diurnal decline that usually happens in the late morning, but neither did they increase their cortisol. Meanwhile, some subjects with lower pre-cold cortisol did experience a little boost as a result of their cold bath.
It's possible that cold water immersion boosts those with depressed cortisol to levels that allow them to benefit from PTSD-targeted therapies, even if the cold water has little effect on those with normal levels of cortisol prior to cold water immersion. That is, the effect of whole-body cold-water immersion might be to normalize cortisol in those subjects with depressed levels, rather than boost it in all subjects. That is, the effect of whole body cold water immersion might be to normalize cortisol in those subjects with depressed levels, rather than boost it in all subjects.
If PTSD is an injury, as Levine claims, then it makes sense to treat it with the tools known to support injury recovery. An ice bath may be one of those tools, both because of the psychological activation of the stress response, and physiological stimulation of beneficial hormones like cortisol. However, no one has yet measured what happens to subjects with chronically low levels of cortisol under whole body cold water immersion.
To shiver, or not to shiver?
I'm often asked about whether it's better to shiver, or to resist the urge to shiver when in the ice bath. My answer is always, "It depends on what you're working on."
If your ice bath practice is primarily for metabolic health, then promoting your shivering thermogenesis will accelerate glucose consumption in the short-term, but may delay the activation and recruitment of brown fat for non-shivering thermogenesis in the longer term. I've been practicing in my Morozko Forge for 2-4 minutes a day, 5-7 times a week now for about four years. I'm certain I've already recruited plenty of brown fat, because I rarely feel cold anymore -- not even in Helsinki in January.
However, I've noticed that the days when I'm most stressed -- maybe I've had a fight with my girlfriend or maybe I'm worried about slow sales during the winter at Morozko Forge -- are the days when I begin shivering almost right away.
What if shivering in my ice bath is the wisdom of my body, releasing my stress?
If that's the case, then like Levine, the trembling in my muscles is not for thermogenesis, but to allow my nervous system to release the fight or flight energy that built up during the argument with my girlfriend. Suppressing that shivering in an attempt to build more brown fat might be the exact opposite of what my body needs from my ice bath in that moment.
About the Author
Thomas P Seager, PhD is an Associate Professor in the School of Sustainable Engineering at Arizona State University. Seager co-founded the Morozko Forge ice bath company and is an expert in the use of ice baths for building metabolic and psychological resilience. Subscribe the Self-Actual Engineering newsletter at https://seagertp.substack.com/ for more information on taking charge of your own physical & mental health.