This post elaborates on the ‘overstimulation’ section of The HSP Owner’s Guide.

In this week’s episode of The Gentle Rebel Podcast, we look at the relationship between sensory processing sensitivity and overstimulation.

Overstimulation is a term we often hear when people talk about high sensitivity. It’s the second word in the DOES acronym after Deep Processing and before Emotional Responsiveness or Empathy, and Sensing Subtleties as a description of core characteristics of the trait.

But what do we actually mean by overstimulated? What does it look like? And is there anything we can do about it other than avoiding stimulating environments and situations? At the get-go, I want to answer that question with a resounding yes. We don’t have to write ourselves out of the situations, environments, and experiences that really matter to us. We have the capacity to build sustainable approaches to this stuff.

https://youtu.be/qy8XxQe7_iU Responsiveness and Stimulation

Because highly sensitive people are all different, it’s important to remember that sensitivity isn’t who we are. It’s more like the rails our nervous system runs on. It is often described as a spectrum of sensory responsiveness. Those on the high end take in a huge amount of sensory data and process it deeply. Those on the low end take in less, and most people are somewhere in the middle. As a species, we have evolved and benefit from individuals existing along this continuum.

Environmental Sensitivity researchers describe this variation through the concept of differential susceptibility. Some individuals are more profoundly influenced by their environment, for better or worse. It’s not about weakness or fragility. It’s about responsiveness and depth of processing. Studies show that highly sensitive individuals flourish in supportive settings but face greater challenges in chaotic ones.

I like to visualise this difference using microphones. A sensitive condenser mic is uniquely effective in quiet, controlled spaces. It picks up every subtle detail. But in a loud environment, it can get overwhelmed by noise. A dynamic mic has a narrower field of responsiveness and can work in almost any environment because it picks up less background noise. Both are useful, but for different purposes. This helps us remember that high sensitivity isn’t a flaw or superpower, it’s just a variation in human temperament, useful in some contexts and less so in others.

What Overstimulation Looks Like

Overstimulation can look different from individual to individual. It is caused by an overload of the nervous system with environmental, emotional, social, or cognitive information.

It’s not always evident to others when a highly sensitive person is overstimulated. Despite appearing calm or composed, HSPs may be grappling with intense physical discomfort or emotional distress due to nervous system overload. Rising levels of stress hormones such as adrenaline, noradrenaline, and cortisol exacerbate this heightened sensitivity, leading to strong reactions to excitement, tension, temperature changes, or sensory stimuli in the environment.

What looks like calmness in a person might be a kind of shutting down. This happens to me when I’ve had too much stimulation – I can look really chilled out, but in actual fact I’m unable to function properly.

You might experience:

Physical symptoms of overstimulation

• Lightheadedness or dizziness
• Internal tremors (feeling shaky inside without visible shaking)
• Heart palpitations or irregular heartbeat sensations
• Nausea or digestive discomfort
• Temperature sensitivity

Cognitive effects of overstimulation

• Difficulty concentrating or focusing on tasks
• Short-term memory lapses
• Mental fog or feeling disconnected from surroundings
• Racing thoughts

Emotional responses

• Irritability disproportionate to the situation
• Sudden emotional surges, such as tears or outbursts of frustration
• Social withdrawal urges
• Heightened startle response

Behavioural changes

• Restlessness or inability to settle
• Increased sensitivity to light, sound, or touch
• Sleep disturbances despite fatigue
• Impulsive decisions to remove oneself from situations

Overstimulation may be subtle. It can build gradually like a low background hum. And sometimes it hits all at once, like flood defences breaking. I remember experiencing it in shops as a child. The fluorescent lights, drudging through aisles, would leave me suddenly feeling drowsy and disconnected, despite being excited at the idea of going shopping.

The Physiology Behind Overstimulation

When overstimulated, the nervous system activates stress responses.

• Neuroception, the subconscious threat detection system, becomes hyper-alert
• Stress hormones such as cortisol and adrenaline flood the system
• The prefrontal cortex becomes less effective, making rational thinking harder
• Sensory filters become less discriminating, letting in too much information

This explains why two people can enter the same environment and one feels energised while the other feels overwhelmed. It’s as much about the state of your nervous system as the external situation, and also about the cumulative load of stimulation you carry between contexts. This is also why it’s important to consider Deb Dana’s words, “story follows state,” which remind us that for highly sensitive people, it’s not as simple as choosing our mindset. We need to start by selecting environmental elements that lead to a calm and less stimulated nervous system before particular thoughts may be able to change.

How to Regulate When Overstimulation Hits

We might think of regulating overstimulation through two broad filters: proactive and responsive.

Proactive regulation involves preparing your nervous system before entering a stimulating environment or situation:

• Notice environments that tend to overstimulate you (and how it tends to happen)
• Consider the contributing factors, e.g. timing, social energy, and sensory intensity
• Plan strategies ahead of time that help you identify green/red flags when facing invitations/opportunities, prioritising margin and bridging between environments, and planning for realistic preparation/recovery space and time where possible

Responsive regulation is what you do when you feel your nervous system becoming overstimulated. Again, different things work for different people, and what works for one person might make it worse for someone else. It’s about experimenting with things like:

• Finding a quiet space with reduced sensory input
• Calming tools such as earplugs, weighted items, or familiar textures, tastes, smells etc
• Breathing techniques
• Stepping outside or moving your body
• Creative practices like doodling, writing, or playing an instrument
• Co-regulating alongside others away from the source of the stimulation

Long-term adaptation might include:

• Scheduling buffer time between activities (and bridges that help you leave and arrive well)
• Identifying recurring triggers and adjusting environments
• Developing a personal preparation/recovery toolkit

The goal isn’t to shut down your sensitivity or avoid life. It’s to notice, understand, and collaborate with your nervous system so you can navigate stimulating environments more comfortably.

The Social Side of Overstimulation

Social interaction is a major source of overstimulation. It’s rarely just the conversation. It can be the context, the unknowns, and the processing afterwards (reliving the conversations, wondering why you said what you did and didn’t say what you should have!) You might really enjoy someone’s company and still leave drained.

Noticing red flags and green flags helps. Big groups with unstructured conversation might deplete you, while small gatherings feel energising. Individual differences matter too. Someone might be draining even if you share interests, while another person energises you despite little obvious common ground.

After-care is crucial. Sometimes being fully drained can feel good if recovery time is planned. The real challenge is when life leaves no margin, stacking one overstimulating event on another. For people with full-time caring responsibilities, this lack of margin is a constant reality.

Sensitivity Beyond the Self

I believe sensitivity has an important social role. Highly sensitive people often notice gaps in care and justice, and their responsiveness and empathy support social cohesion. Noticing and responding to sources of stimulation isn’t just about individual survival; it’s tied to our capacity to change the world around us. It’s about shaping communities, environments, and expectations to work for different people. Not least because when we make the world conducive for individuals to flourish, it is good for all of us.