What a Trauma and Anxiety Psychologist Wants You to Know About Calming the Nervous System
By Dr. Lienna Wilson, Licensed Psychologist | Vagus Vitality
Trauma and anxiety can both leave the nervous system stuck on high alert. When a strong emotion hits, it can take over the whole body: the racing heart, the tight chest, the urge to act right now. In those moments, trying to think your way out rarely works, because the thinking brain is not fully online. That is where body-based skills that engage the vagus nerve can help.
To learn more, I had the pleasure of interviewing Anna Sheedy, PsyD, a highly skilled licensed psychologist and founder of the Center for Valued Change, where she helps teens and adults heal from trauma and quiet anxiety. Dr. Sheedy is trained in Cognitive Behavioral Therapy, Cognitive Processing Therapy, and Dialectical Behavior Therapy (DBT), and she often teaches clients fast-acting calming skills drawn from DBT. I asked her how these skills work on the nervous system, who they help most, and how they lay the groundwork for deeper trauma healing.
What Is DBT?
Dialectical Behavior Therapy (DBT) was developed by psychologist Marsha Linehan, PhD, to help people whose emotions come on fast, hit hard, and are slow to settle, a pattern clinicians call emotion dysregulation. Originally designed for people with borderline personality disorder and chronic suicidal behavior, DBT balances two ideas that can seem at odds: accepting yourself as you are, and working actively to change. It teaches four sets of skills: mindfulness, distress tolerance, emotion regulation, and interpersonal effectiveness.
DBT has a strong research base. In people at high risk for suicide, it has been shown to help reduce suicide attempts and self-harm (Linehan et al., 2015). It has also been adapted for trauma and was shown to reduce PTSD severity in women with PTSD related to childhood abuse (Bohus et al., 2020). Dr. Sheedy draws on DBT skills in her work with trauma and anxiety, and one of the skills she teaches most often is built around a reflex that runs directly through the vagus nerve.
What Is the Dive Reflex?
“The dive reflex is a biologically hardwired reflex that all mammals have,” Dr. Sheedy explains. “When we are submerged in cold water, our bodies go into ‘conservation mode.’ Our parasympathetic nervous system gets activated, which means everything slows down.” Heart rate drops and the body shifts toward conserving energy. Much of that slowing is carried by the vagus nerve, the main nerve of the parasympathetic nervous system. Research supports its calming potential: in a study of adults with and without panic disorder, submerging the face in cold water for 30 seconds while holding the breath significantly lowered heart rate and reduced self-reported anxiety and panic symptoms in both groups (Kyriakoulis et al., 2021).
Why DBT Teaches This Skill
Dr. Sheedy explains that the dive reflex matters because of who DBT is designed to help. “Clients who seek DBT struggle immensely to regulate their nervous systems; they can get emotionally dysregulated very quickly,” she says. “Practicing the dive reflex helps these individuals quickly slow down, which brings down the intensity of their emotions. This can help them access their other skills to help them problem-solve better.”
The dive reflex belongs to a family of DBT skills known as distress tolerance skills. Dr. Sheedy notes that other skills in this group, such as paced breathing and progressive muscle relaxation, “have a similar purpose as the dive reflex: they activate the parasympathetic nervous system.” Slow, paced breathing in particular has a well-studied relationship with vagal activity and heart rate variability (Lehrer & Gevirtz, 2014).
The goal, Dr. Sheedy emphasizes, is not calm for its own sake. “Parasympathetic nervous system activation allows us to ‘rest and digest’ and slow down overall,” she says. “In the context of DBT, these skills help lower the intensity of an emotional experience so we can access rational thought and problem-solving skills. We cannot access those things when we are emotionally dysregulated.” And once the thinking brain comes back online, the payoff is real. “Being able to access rational thought helps us figure out how to best act and proceed from our values-based self, instead of our impulsive, emotionally based self.”
Mindfulness and the Dive Reflex: Separate but Intertwined
“Mindfulness is the core of DBT,” Dr. Sheedy says. “It is the skill set that everything else in DBT rests on.” She sees mindfulness and body-based skills like the dive reflex as working together to slow down physiological responses, but not as interchangeable. “Practicing mindfulness can certainly be a route to activating the parasympathetic nervous system, but it is often not enough to dial down emotional intensity in individuals who are in DBT,” she explains, “so I do see them as separate, but intertwined, systems. They are both very necessary when it comes to emotion regulation.”
Who Benefits Most from Rapid-Acting Skills
“Individuals who benefit from these rapid-acting skills tend to be high in emotional intensity and impulsivity,” Dr. Sheedy says. “These are individuals who naturally feel very deeply and strongly; when an emotion comes on, it often comes on very fast and very hard.” In those highly emotional states, people often make choices that end up making their situations worse. Anyone who struggles with this pattern can benefit from distress tolerance skills, but Dr. Sheedy is clear that these skills have a specific job. “Once we are in a calm, wise state, however, that is when we do not need to use these skills anymore,” she says. “If someone is calm but still struggling, I would steer them towards a different skill set, like emotion regulation or interpersonal effectiveness.”
Why Suppressing Emotions Backfires
“Many individuals who have experienced complex and chronic trauma are very afraid of experiencing emotion,” Dr. Sheedy explains. “They often spend a lot of time trying to suppress and control their emotional experiences, which actually backfires; we know that emotional suppression actually intensifies emotion.” The result is a self-reinforcing loop: the harder someone pushes feelings down, the more intense and out of control those feelings become. Research on emotion regulation points in the same direction. In one experiment with people diagnosed with anxiety and mood disorders, those instructed to suppress their emotions during a distressing film showed an increase in heart rate, while those instructed to accept their emotions showed a decrease in heart rate and less negative emotion afterward (Campbell-Sills et al., 2006).
This is why Dr. Sheedy often starts with distress tolerance. “A lot of my work focuses on teaching these distress tolerance skills first so that clients can learn how to experience some emotion in a way that feels safe to them,” she says. “In my experience, this helps trauma clients feel safer and more willing to engage in trauma reprocessing.” The skills-first approach has a relational benefit too. According to Dr. Sheedy, “It can also build trust and rapport with me, which helps increase a sense of safety before engaging in tougher parts of trauma work.”
How Long Does It Take to Feel Safe Again?
“It really depends in my experience,” Dr. Sheedy says. “There are so many factors that affect someone’s ability to learn that they are safe again.” For people with high emotional reactivity and a long-standing pattern of extreme avoidance, trauma work may take longer to help them feel safe. “For individuals who have more willingness and openness to face trauma triggers and experience discomfort, it may take a relatively short period of time,” she explains. “With very focused trauma work where we can meet consistently, build trust quickly, and begin the trauma processing, I have seen people transform in as little as 12 sessions (though it often takes longer).” That timeline is consistent with structured trauma treatments such as Cognitive Processing Therapy, one of the approaches Dr. Sheedy is trained in, which is typically delivered in about 12 sessions and has strong support from randomized trials (Resick et al., 2002).
Building Trust with Trauma Survivors
Many of the trauma survivors Dr. Sheedy works with have experienced interpersonal trauma, meaning harm inflicted by another person. For them, she says, “building trust and safety from the start is essential. The therapeutic relationship is a vehicle to start experimenting with trust and safety.” Dr. Sheedy describes her approach as open, honest, and genuine. “I have very little to hide with these clients because I know that the more open I am, the more they can learn to trust me,” she says. “I am always consistent, and I let them know that I want them to experience a sense of control and consent within our work.” The research backs up this emphasis: across hundreds of studies, the strength of the therapeutic alliance is one of the most consistent predictors of how well therapy works (Flückiger et al., 2018). For Dr. Sheedy, these strategies help clients “feel seen, heard, and cared for before we embark on the trauma work.”
How to Try the Dive Reflex
If you want to try this skill yourself, here is how Dr. Sheedy teaches it. The classic version is to fill a bowl with cold water, submerge your face, and hold your breath for up to 30 seconds. “If that feels too scary or overwhelming for some people,” Dr. Sheedy says, “they also have the option to splash cold water on their face, or take a cold pack from the freezer and blot their face and neck with it.”
When emotions run hot, the answer is not to force them away. As Dr. Sheedy’s work shows, calming the body first, through skills like the dive reflex and paced breathing, can open the door to clearer thinking, a safer relationship with emotion, and eventually deeper healing from trauma and anxiety.
About Anna Sheedy, Psy.D.
Dr. Sheedy is a licensed psychologist and founder of the Center for Valued Change in King of Prussia, Pennsylvania, where she specializes in trauma and anxiety. She earned her doctorate in clinical psychology from La Salle University and completed her postdoctoral residency specializing in trauma, anxiety disorders, and personality disorders in teens and adults. Dr. Sheedy is trained in Cognitive Behavioral Therapy, Cognitive Processing Therapy, and Dialectical Behavior Therapy, and she sees clients in person in King of Prussia and virtually across Pennsylvania and other PSYPACT states.
Note: skills like the dive reflex are typically taught by a trained clinician as part of a broader treatment plan. Because the dive reflex slows heart rate, check with your doctor before trying cold-water face immersion if you have a heart condition, a history of fainting, an eating disorder, or other medical concerns. If you’re struggling with intense emotions or the effects of trauma, talk to a qualified mental health professional about what’s right for you.
References
Bohus, M., Kleindienst, N., Hahn, C., Müller-Engelmann, M., Ludäscher, P., Steil, R., Fydrich, T., Kuehner, C., Resick, P. A., Stiglmayr, C., Schmahl, C., & Priebe, K. (2020). Dialectical behavior therapy for posttraumatic stress disorder (DBT-PTSD) compared with cognitive processing therapy (CPT) in complex presentations of PTSD in women survivors of childhood abuse: A randomized clinical trial. JAMA Psychiatry, 77(12), 1235-1245. https://doi.org/10.1001/jamapsychiatry.2020.2148
Campbell-Sills, L., Barlow, D. H., Brown, T. A., & Hofmann, S. G. (2006). Effects of suppression and acceptance on emotional responses of individuals with anxiety and mood disorders. Behaviour Research and Therapy, 44(9), 1251-1263. https://doi.org/10.1016/j.brat.2005.10.001
Flückiger, C., Del Re, A. C., Wampold, B. E., & Horvath, A. O. (2018). The alliance in adult psychotherapy: A meta-analytic synthesis. Psychotherapy, 55(4), 316-340. https://doi.org/10.1037/pst0000172
Kyriakoulis, P., Kyrios, M., Nardi, A. E., Freire, R. C., & Schier, M. (2021). The implications of the diving response in reducing panic symptoms. Frontiers in Psychiatry, 12, 784884. https://doi.org/10.3389/fpsyt.2021.784884
Lehrer, P. M., & Gevirtz, R. (2014). Heart rate variability biofeedback: How and why does it work? Frontiers in Psychology, 5, 756. https://doi.org/10.3389/fpsyg.2014.00756
Linehan, M. M., Korslund, K. E., Harned, M. S., Gallop, R. J., Lungu, A., Neacsiu, A. D., McDavid, J., Comtois, K. A., & Murray-Gregory, A. M. (2015). Dialectical behavior therapy for high suicide risk in individuals with borderline personality disorder: A randomized clinical trial and component analysis. JAMA Psychiatry, 72(5), 475-482. https://doi.org/10.1001/jamapsychiatry.2014.3039
Resick, P. A., Nishith, P., Weaver, T. L., Astin, M. C., & Feuer, C. A. (2002). A comparison of cognitive-processing therapy with prolonged exposure and a waiting condition for the treatment of chronic posttraumatic stress disorder in female rape victims. Journal of Consulting and Clinical Psychology, 70(4), 867-879. https://doi.org/10.1037/0022-006X.70.4.867