Overstimulation and High Sensitivity (The HSP Owner’s Guide)

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://www.youtube.com/watch?v=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 dizzinessInternal tremors (feeling shaky inside without visible shaking)Heart palpitations or irregular heartbeat sensationsNausea or digestive discomfortTemperature sensitivity Cognitive effects of overstimulation Difficulty concentrating or focusing on tasksShort-term memory lapsesMental fog or feeling disconnected from surroundingsRacing thoughts Emotional responses Irritability disproportionate to the situationSudden emotional surges, such as tears or outbursts of frustrationSocial withdrawal urgesHeightened startle response Behavioural changes Restlessness or inability to settleIncreased sensitivity to light, sound, or touchSleep disturbances despite fatigueImpulsive 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-alertStress hormones such as cortisol and adrenaline flood the systemThe prefrontal cortex becomes less effective, making rational thinking harderSensory filters become less discriminating, letting in too much information This explains why two people can enter the same environment ...