Do you often struggle with feelings of anxiety or depression? Perhaps you find yourself feeling disconnected, lethargic, or fatigued, or alternatively, anxious, overwhelmed, and frazzled? These experiences might indicate a narrow window of tolerance—a concept that describes our nervous system's capacity to handle stress while staying engaged and present.

As a clinician specializing in neurodivergence, I’ve observed how understanding and expanding the window of tolerance can help individuals become more grounded and regulated in their daily lives. This concept is particularly relevant for neurodivergent people, who often experience a smaller window of tolerance, making it challenging to navigate day-to-day stressors. By learning about and working with our window of tolerance, we can enhance our ability to manage stress and lead more fulfilling lives.

What is the Window of Tolerance?

The window of tolerance is a metaphor for a state of nervous system balance where we can stay present, adaptable, and engaged with our surroundings. When we operate within this window, we can effectively respond to everyday stressors and challenges. In this state, the sympathetic (responsible for "fight or flight") and parasympathetic (responsible for "rest and digest") branches of our nervous system work together smoothly, allowing us to navigate life with resilience and grace. The larger our window of tolerance, the more we can handle without becoming dysregulated. This state is often referred to as having a regulated nervous system.

The Vagus Nerve & Vagal Tone

Imagine the sympathetic nervous system as the gas pedal and the parasympathetic nervous system as the brakes in a car—then the vagus nerve is like the driver. This cranial nerve plays a key role in regulating essential bodily functions, including heart rate, breathing, blood pressure, and digestion.

Because the vagus nerve is part of the parasympathetic nervous system, it helps manage the balance between "rest and digest" and "fight or flight" responses. When it’s active, the vagus nerve slows the heart rate, lowers blood pressure, and promotes relaxation. When less active, the body is more geared towards action and alertness.

High vagal tone means the vagus nerve is efficiently managing this balance, allowing for a more flexible and adaptable nervous system that can handle stress and recover quickly. This flexibility expands your window of tolerance, making it easier to stay present and grounded during daily challenges.

For more details on the vagus nerve and its role in the nervous system, check out my in-depth article on the neurodivergent nervous system.

The Ideal Level of Arousal

Throughout our day, our nervous system naturally shifts between states of higher and lower arousal. Sometimes, our sympathetic nervous system (the gas pedal) takes the lead, like when we’re exercising or dealing with a challenge. Other times, our parasympathetic nervous system (the brakes) becomes more active, such as when we’re winding down for sleep.

These fluctuations are normal and necessary, much like driving a car requires different levels of acceleration and braking. As long as we remain present, grounded, and engaged, we’re operating within our window of tolerance, effectively managing these shifts in arousal.

The Window of Tolerance

The window of tolerance is the optimal zone where we can manage and process intense emotions and stress in a healthy way. When we're within this window, our nervous system is balanced, allowing us to respond to challenges without becoming overwhelmed. In this state, our executive functioning—our ability to plan, focus, and manage tasks—works at its best.

Being present, calm, grounded, and engaged are signs that we're in our window of tolerance. In this state, the sympathetic and parasympathetic nervous systems work together harmoniously, like the gas and brake pedals of a car, ensuring smooth and adaptive responses to everyday stress.

However, when stress exceeds what we can handle, we exit this window and become dysregulated. This can lead to either hyperarousal (overactivation) or hypoarousal (shutdown). Let’s explore what these states look like.

Hyperarousal

Hyperarousal is a state where the sympathetic nervous system dominates, leading to an overactivation of the fight-or-flight response. In this mode, the body becomes mobilized for action, often resulting in feelings of anxiety, aggression, hyper-vigilance, impulsiveness, or intense fear. Physically, hyperarousal is marked by an increased heart rate, rapid and shallow breathing, high blood pressure, and elevated stress hormones like adrenaline and cortisol. When stuck in this state, we may find ourselves becoming more argumentative, defensive, panicky, or impulsive.

Hypoarousal

If hyperarousal is a state of sympathetic dominance, then hypoarousal is a state where the nervous system shuts down due to overwhelm, leading to reduced energy and activity. In this state, we might feel depressed, fatigued, foggy, numb, and dissociated. Dissociation is a common response in hypoarousal, where the mind disconnects from the present moment as a protective mechanism. Physiologically, hypoarousal can result in a slowed heart rate, shallow breathing, and disruptions in digestion. When operating from this place, it can be difficult to make decisions, stay focused, or engage socially, as the body is in a state of conservation rather than activation.

What Can Affect the Window of Tolerance

The size of our window of tolerance determines how much stress we can handle without becoming hyperaroused or hypoaroused. A larger window allows us to manage stress more effectively, while a smaller window makes it easier to become dysregulated. Various factors can influence the size of our window of tolerance.

One significant factor is trauma. Individuals who have experienced ongoing trauma, especially in childhood, often have a smaller window of tolerance. Living in a state of constant stress during formative years can prevent the nervous system from developing the capacity to regulate effectively. This results in a nervous system that is either always on high alert or constantly shut down as a means of self-protection.

Neurodivergence is another factor that can impact the size of the window of tolerance. People with conditions such as OCD, ADHD, or Autism often have a more narrow window of tolerance. This could be due to a combination of factors, including the inherent vulnerabilities in their neurological and sensory systems, higher rates of adverse experiences, and challenges with sensory processing.

The Window of Tolerance and Neurodivergence

Autistic and ADHD individuals often have what I call more “rigid nervous systems” compared to neurotypicals, as measured by reduced heart rate variability. This rigidity leads to a smaller window of tolerance and lower vagal tone, making it easier to become dysregulated—whether in a state of hyperarousal, hypoarousal, or both.

Additionally, neurodivergent individuals often have a heightened stress response, with increased cortisol and adrenaline release and higher HPA axis activation. These factors make returning to a regulated state more challenging, often requiring extra time, effort, and support.

Understanding your Window of Tolerance

To get to know your nervous system, it’s helpful to regularly check in with yourself—a practice sometimes called nervous system mapping. This might involve setting aside time, perhaps once or twice a day, to take a breath, scan your body, and observe how you’re feeling.

For example, during a body scan, you might notice signs like slow breathing or fatigue, indicating hypoarousal. Or, you might feel a racing heart or tension, pointing to hyperarousal. If you feel grounded and calm, you're likely within your window of tolerance.

Consistently checking in can reveal patterns over time. Personally, I tend to experience hypoarousal when dysregulated, so I might engage in activities that help energize my nervous system, like walking or listening to music. Understanding and tracking these patterns is a helpful first step in gradually expanding your window of tolerance.

Another way to understand your window of tolerance is by tracking your heart-rate variability (HRV). HRV reflects how adaptable your heart is to changes, with higher HRV indicating a larger window of tolerance. Devices like Apple Watch or a Fitbit can help track HRV. To learn more about HRV, check out my detailed article here.

Increasing your Window of Tolerance

There are various tools and practices that can help expand your window of tolerance. Psychological work, such as processing trauma and healing attachment wounds, can be foundational in this process. Beyond that, working directly with the nervous system through specific exercises can also be helpful. When introducing new practices, it’s important to take it slow. Trying one or two exercises consistently for a month before adding more can prevent overwhelm.

Breathwork

Slow, deep breathing can be a simple yet powerful way to activate the vagus nerve, easing anxiety and helping you feel more grounded. On the flip side, quick, shallow breaths can kickstart the sympathetic nervous system, giving you a boost of energy when needed.

Laughter

A good laugh really is great for your health! Laughter can stimulate the vagus nerve through diaphragmatic breathing. Just ten minutes of laughter a day can make a difference, so try to incorporate more humor into your life.

Humming, Chanting, & Singing

Using your voice mindfully through humming, chanting, or singing can activate the vagus nerve. Chanting “om,” for example, can help calm the part of the brain responsible for stress and emotions.

Vagal Nerve Stimulators

Using a vagal nerve stimulator can help strengthen your vagal tone, enhancing the flexibility of your nervous system. My personal favorite is the Sensate. Use code NeuroInsights to get 10% off. Additionally, tools like the Sensate device, the Safe and Sound Protocol, or a TENS unit with ear clips can also help stimulate the vagus nerve.

Exercise & Movement

Moving your body is a great way to tone the vagus nerve and increase heart rate variability. Whether it’s a vigorous walk, some weightlifting, or gentle somatic movement, find what feels good for you. Weight lifting can offer deep pressure on the joints, which many neurodivergent folks find calming.

Mindfulness & Meditation

Mindfulness and meditation can do wonders for your mental health. They’re not only linked to better memory and reduced brain inflammation but also help boost heart rate variability. When combined with breathwork, these practices can also activate the vagus nerve.

Probiotics & Omega-3s

Taking care of your gut health with probiotics and omega-3s can have a direct impact on your nervous system. Since the vagus nerve is closely connected to your digestive system, maintaining a healthy gut can enhance nervous system function and contribute to better stress resilience and emotional regulation.

Massage

Massage can be a soothing way to increase vagal tone, whether it’s from someone else or self-massage. This kind of mindful touch stimulates the vagus nerve and releases oxytocin, the bonding hormone.

Havening

Havening is a self-soothing technique that involves comforting, therapeutic touch. This can boost serotonin levels, creating a sense of calm and safety. Try cupping your hands on your cheeks or crossing your arms as if giving yourself a hug.

Cold Exposure

Incorporating brief cold exposure into your routine—like ending your shower with 30 seconds of cold water or placing ice on the back of your neck—can help stimulate vagal activity and improve heart rate variability. Just be mindful and use caution, especially if you have certain health conditions, as cold exposure can be intense.

Relaxation Exercises

Relaxation exercises like deep breathing, progressive muscle relaxation (PMR), or meditation can help bring your body out of a stressed state. These are great tools to use before bed, in the morning, or whenever you need to recover from stress.

Summary: The Window of Tolerance

When we operate within our window of tolerance, we face the day with clarity, grounding, and engagement. A larger window means we can handle more stress, change, and challenges while remaining present.

However, when overwhelmed, we become dysregulated, either hyperaroused or hypoaroused, with our nervous system taking over to protect us—sometimes in ways that aren't beneficial. Understanding and expanding this window through self-observation and regulating exercises can build our capacity for stress and change over time.

If you're interested in exploring this topic further, consider checking out our Nervous System Workbook. for more resources on understanding your nervous system and expanding your window of tolerance.

References

Beauchaine, T. P., Gatzke-Kopp, L., Neuhaus, E., Chipman, J., Reid, M. J., & Webster-Stratton, C. (2013). Sympathetic- and parasympathetic-linked cardiac function and prediction of externalizing behavior, emotion regulation, and prosocial behavior among preschoolers treated for ADHD. Journal of consulting and clinical psychology, 81(3), 481–493. https://doi.org/10.1037/a0032302

Bellato, A., Arora, I., Hollis, C., & Groom, M. J. (2020). Is autonomic nervous system function atypical in attention deficit hyperactivity disorder (ADHD)? A systematic review of the evidence. Neuroscience & Biobehavioral Reviews, 108, 182-206.

Bergland, C. (2016, September 18). How self-initiated laughter can make you feel better. Psychology Today.

Christensen J. H. (2011). Omega-3 polyunsaturated Fatty acids and heart rate variability. Frontiers in physiology, 2, 84. https://doi.org/10.3389/fphys.2011.00084

Gerritsen, R. J. S., & Band, G. P. H. (2018). Breath of Life: The Respiratory Vagal Stimulation Model of Contemplative Activity. Frontiers in human neuroscience, 12, 397.

Jungmann, M., Vencatachellum, S., Van Ryckeghem, D., & Vögele, C. (2018). Effects of Cold Stimulation on Cardiac-Vagal Activation in Healthy Participants: Randomized Controlled Trial. JMIR formative research, 2(2), e10257.

Fenning, R. M., Erath, S. A., Baker, J. K., Messinger, D. S., Moffitt, J., Baucom, B. R., & Kaeppler, A. K. (2019). Sympathetic-Parasympathetic Interaction and Externalizing Problems in Children with Autism Spectrum Disorder. Autism research : official journal of the International Society for Autism Research, 12(12), 1805–1816.

Gourine, A. V., & Ackland, G. L. (2018). Cardiac vagus and exercise. Physiology, 33(6), 486-487.

Gerritsen, R. J. S., & Band, G. P. H. (2018). Breath of Life: The Respiratory Vagal Stimulation Model of Contemplative Activity. Frontiers in human neuroscience, 12, 397. https://doi.org/10.3389/fnhum.2018.00397

Spratt, E. G., Nicholas, J. S., Brady, K. T., & et al. (2012). Enhanced cortisol response to stress in children with autism. Journal of Autism and Developmental Disorders, 42(1), 75-81.