A woman who appears to be a Highly Sensitive Person leaning against a fence watching horses

Why Are Some People Highly Sensitive & Most Aren’t?

Ever wonder why some people are Highly Sensitive, but most people are not?

Highly Sensitive People (HSPs) are born that way. Highly Sensitive.

High Sensitivity is not a disorder. Nor is it an attempt to be dramatic or to get attention. It’s a trait in the same way eye color is a trait.

HSPs’ nervous system is calibrated differently than non HSPs’.

The way HSPs process social, environmental, emotional, and physical stimulation is more intense and at a deeper level than people without the trait. It is biological.

If you are a Highly Sensitive Person, you’ve likely been called “too sensitive”, at least a thousand times. And advised more than a few times to “have a thicker skin” or to “lighten up.” (If I had a nickel for every time these comments were made to me….)

You may be among the 15-20% of people who is Highly Sensitive if, among other features, you tend to:

  • Notice nuance and details
  • Get stressed out or annoyed in chaotic environments – and need to retreat somewhere quiet to regroup
  • Feel rattled when there’s a lot to do in a short period of time
  • Find that you’re unable to watch violent movies or television shows – it’s just too disturbing
  • Experience peace and awe in nature
  • Need plenty of sleep, consistently, in order to function
  • Are prone to getting hangry

The High Sensitivity trait, which occurs equally in males and females, is a result of a combination of genes. In fact, scientists have discovered at least three different genetic combinations among Highly Sensitive People. The gene variants include different configurations of the following neurotransmitters:

  • Serotonin Transporter
  • Dopamine
  • Norepinephrine

Let’s look at these in more detail.

1. Serotonin Transporter and Highly Sensitive People:

Serotonin transporter is a chemical that transports serotonin out of the brain. HSPs have a variant of this gene (officially called 5-HTTLPR).

The 5-HTTLPR gene variant increases sensitivity to surroundings and is associated with learning from experience. The presence of the gene enhances the effects of both good and adverse childhood experiences.

This may explain why childhood experiences–positive and adverse–impacts wellbeing so much for a Highly Sensitive adult. For better or worse, HSPs’ childhood experiences affect them more than does the childhood of a person without the trait.

2. Dopamine:

This neurotransmitter is known as the reward chemical.

If you have a sensitive nervous system, you don’t need much to feel “rewarded” by external stimuli. Chaotic, noisy, loud environments exhaust rather than excite you.

Let’s just say you don’t exactly get the same kind of dopamine hit that your non Highly Sensitive friends gets at a rock concert or other loud venue.

The same Dopamine variant is also relevant in understanding why HSPs feel more rewarded by positive social or emotional cues.

3. Norepinephrine and Highly Sensitive People:

Norepinephrine helps the body with the stress response.

And there’s one variant, common in HSPs, that boosts emotional vividness. If you have it, you tend to experience emotional aspects of the world intensely. You may also have more going on in parts of the brain that create internal emotional responses to experiences.

Most HSPs respond more strongly to emotions than do non-HSPs. In addition, they often notice emotional nuances where others don’t pick up on anything.

If you’re Highly Sensitive, this gene variant may be at least partly responsible. And it directly drives the level of empathy and awareness you have for others’ feelings.

Evolutionary Benefit

So if 15-20% of a population has something in common, such as High Sensitivity, it is not considered a disorder. The rate is a lot of people in total but still uncommon enough that HSPs often report feeling weird or different.

HS has been found in at least 100 species, including fish, horses, fruit flies, and chimpanzees.

Highly Sensitive People and HS animals pick up on more environmental cues, recognize things that others don’t, and make wise decisions in new settings. They don’t rely on routines, which non HSPs and non HS animals tend to do.

There is definite survival advantage to being keenly aware of your environment.

In general, people who take the time to notice environmental cues before making a decision come out ahead — even with a high cost to doing so. HSPs’ sensitivity means they make better and better decisions over time.

So, here is the key point: If the rate of High Sensitivity were 100%, everyone would notice nuance and details. No one would have any advantage. That could explain why HSPs are about 15-20 percent of the population rather than 90, 95, of 100 %!

No more wondering why no one else thinks things through the way HSPs do. HSPs are able to see things others don’t see and feel emotions others don’t feel, That in and of itself creates value.

Further, HSPs feel positive things and negative things more intensely. Highs can be joyous, and lows can be horrible. For the survival of our species, only a subset with those features could exist.

The world needs diversity of all kinds, including people who are Highly Sensitive. And people who are not.

Dr Elayne Daniels is a psychologist in MA who enjoys helping HSPs thrive. Contact her here.

Dr. Elayne Daniels


  1. Sally Mahoney on April 20, 2022 at 9:56 am

    When I mentioned to my doctor that the tramadol I take for fibromyalgia does much more for my depression/anxiety than my actual depression medicine does, she said, “You must be really sensitive to serotonin!” So I decided to look online for information about serotonin sensitivity and found your article. I can say that the part about finding peace and awe in nature is very true for me, and I had never before seen anything written about it in this context. I was much younger than my siblings, so they had all left for college by the time I started 5th grade (the first one left when I was 5 years old). After their departure, someone suggested I ride my pony to check on snd count our cattle each day, and I did. The farm and nature became my dearest companion from that day till I left for college. At a young age I could tell that without that time in nature I would’ve had great difficulty making it through those years. And nature is still huge to me—the sky, the trees, the sound of the leaves and grasses and snowmelt.
    Tramadol has helped lessen the pain of sensitivity without losing the happy end of the spectrum. This trait definitely runs in my family.

    • Dr. Elayne Daniels on April 20, 2022 at 6:55 pm

      Hi Sally,

      Thank you for sharing about your experience with medication. HSPs do often have a different kind of reaction to medications than do non-HSPs.
      Your description of nature and of your relationship with it is beautiful and brought me a huge smile!
      Thank you.

  2. Melissa on April 29, 2022 at 2:56 pm

    Is there any known connection between HSP and the autism spectrum, specifically what we once called “aspergers” ?

    • Dr. Elayne Daniels on April 29, 2022 at 3:59 pm

      Hi Melissa,

      Thank you for the great question!

      The research I’ve done suggests that High Sensitivity (HS) and Autism Spectrum Disorder (ASD) are NOT the same thing, although there’s overlap. For example, HSPs and people with Autism show more sensitivity to the environment than do people without HS or Autism. In both cases, overwhelm is common if there is too much environmental stimulation. (Such as sound, smell, commotion…)

      Recent research highlights 3 main differences between HS and ASD:

      1. People on the AS often have social difficulties, such as with reading social cues, making eye contact, or with mirroring (e.g. smiling when smiled at).
      People with HS tend to have a ‘sixth sense’ and are ultra attuned to social cues and mirroring.

      2. Relationships are important to HSPs and People with ASD. But to HSPs, there is more meaning involved. Basically, HSPs tend to experience social interactions as more rewarding than do people with ASD.

      3. The brains of HSPs and people with ASD are wired very differently, with one exception. The brains of both HSPs and people with ASD are more easily stimulated than are the brains of people without HS or ASD. (See #1) However, the areas of the brain related to calmness, emotion, and sociability are way more active for HSPs than for people with ASD.

      A great reference to learn more about the similarities and differences between HS and Autism is: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5832686/

      Hope that helps, and thanks again for the question!

  3. Heather Ripley on November 24, 2022 at 4:57 pm

    Thanks for this writing, Dr. Daniels. I find the science-focussed explorations of the HSP trait help ground it for me. I only found out about it in April this year, so am still digesting all that it means!
    Do you happen to know if there is any research that shows a relationship between suicidality and the HSP trait?

    • Dr. Elayne Daniels on November 27, 2022 at 9:18 am

      Hi Heather,
      Thank you for reaching out. There is indeed a lot to digest.
      Your question about high sensitivity and suicidality is a really good one. I am going to look into it!
      I am thinking that HSPs may indeed be at higher risk of suicide. There may also be some protection the trait provides.
      Said in another way, differential susceptibility could account for a higher probability of suicide and/or less probability due to protective factors.
      HSPs tend to be acutely aware of life’s dichotomies, including both the strengths and vulnerabilities that accompany the trait. Another example is the awareness that without sorrow there is no joy.
      When I find more information on the topic, I will email you privately if that’s ok?

      • Heather on December 1, 2022 at 7:34 am

        Hi Dr. Daniels,
        Thank you so much! I appreciate you checking into this. I’ve been researching it (online) and haven’t found any answers yet. I think what you say about differential susceptibility makes sense. Please feel free to email me when/if you find anything. I did check the sensitivityresearch.com website a few months back and emailed them but didn’t hear back.

        • Dr. Elayne Daniels on December 1, 2022 at 5:23 pm

          Dear Heather,

          Thank you for following up! I will be in touch!

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