Are Highly Sensitive People More Prone to Illness?

I understand that on social media the question keeps arising about various health issues to which HSPs seem to be more prone–illnesses such as fibromyalgia, chronic fatigue, and migraines. The short answer: It may be an HSP also has an illness that they see as related to their sensitivity. But there is no clear research evidence that being an HSP directly causes any physical illness.

That was the short answer. Now the long answer. A shortened version of this will be on Psychology Today. This may be the longest blog I have written. I thought of dividing it into two parts, but I feel it all belongs together. So please be patient if I did not proof read it perfectly.

What Is SPS, Really?  

In a moment I will discuss the six actual research studies done so far that found an association between SPS (sensory processing sensitivity, another term for the trait) with health problems. But remember, an association or correlation, another term for the same thing, does not mean causation.  (By the way, if you are poking around on the internet looking at illnesses, don’t get our “HSP” confused with the initials for Henoch-Schönlein purpura!)

So let’s be clear about what SPS actually is, because it is literally hard to see.  SPS is one of two largely invisible survival strategies found in many species.  One strategy, employed by the majority, does not involve paying attention to the details of situations, and they do fine as long as these details do not matter very much, which is true most of the time.  They dash into situations or ignore them, always without a great deal of consideration.  (See Max Wolf and others on “Evolutionary emergence of responsive and unresponsive personalities,” published in 2008, although I warn you it is difficult reading.)

A substantial minority, in humans those we call HSPs, are using a different survival strategy.  They do pay attention to the details, and sometimes that pays off.  There is not much to see, however. when people are just paying attention and thinking about what they are observing.  That is why the trait can seem almost invisible.  HSPs simply soak up their environments and adapt.

Usually we are adapting to a social environment. All animals need to find food and reproduce, and in humans most of this occurs in a highly social world–jobs, dating, family life, friendships, support groups, etcetera.  I am going to argue that when all goes well, HSPs are largely invisible within most social environments. Other people may notice that they think deeply, notice details others miss, or have a great deal of empathy for others.  Sometimes they are noticed for preferring quiet or avoiding noisy, chaotic situations.  But most HSPs usually learn how to tolerate some over stimulation if is brief and generally to fit in and not make a “big deal” of their needs, even if they do feel a bit different than others.

Of course, HSPs do feel different, always being a minority.  Why always a minority? Not because this strategy of observing is not as good as one of ignoring details.  Its usefulness depends on the situation.  The example I like to use is a traffic jam (rather than famines or fires). If only a few people know their city well enough to find a short cut around a traffic jam, the short cuts remains a short cut.  When everyone figures out the short cut, it fills up with traffic and ends up taking just as long.  But generally, HSPs fit in well enough with others.

Differential Susceptibility Determines Our Visibility–The Visible HSP is the Stressed HSP 

HSPs are not always invisible, however. The only problem with this strategy of learning to adapt to the people around us is that, for all humans, much of that learning occurs in childhood, and humans tend to be conservative—the safest strategy is to expect people to keep treating us in the way they did in the past.  (Remember that for later.) However, if what a person learned in childhood about how to behave and what to expect from others is not working in adulthood, that person may become more visible, whether an HSPs or not, until they make a better adaptation.  For example, if someone grew up thinking everyone is always honest, the people around them will probably hear about the first time they are victims of a scam.   But since HSPs in particular absorb the details of childhood, if it was a difficult childhood. that can result in their being, very very visible.

This characteristic of HSPs that we are more affected than others by our childhood is an example of “differential susceptibility,” the concept developed and well researched by Jay Belsky and Michael Pluess.  Sticking to what we learned in childhood through noticing all the details gives us a huge advantage if the people around us loved us, made us feel secure, were reasonable when conflicts arose, and taught us behaviors that would help us adapt as we grew up.  We absorb this good stuff better than other children in the same good environment.  Naturally we grow up expecting to be liked and to like others.

Under these good-enough conditions, our trait is, as I said, mostly invisible, in that we fit in nicely into a “nice” social world. Sure, we may feel different, get easily overstimulated, and have trouble setting firm boundaries.  But mostly we hide all that and enjoy ourselves.  We are curious, processing everything deeply, and feel deep empathy, which tends to make others enjoy our company.

The problems arise if we had a different sort of childhood.  Maybe we felt threatened by the people around us and had to learn to adapt to that. Maybe we learned as children not to trust people, or that getting our needs met required being extra nice or clever. As a result, even as adults we may doubt that people really care about us, and we think we must work hard to get a bit of love and respect.  We are anxious, shy, or crazy overachievers.  Or maybe we were harshly punished or bullied, so even now we are always watching out for trouble, ready to defend ourselves.  Or we expect to be defeated, leaving us feeling hopeless and depressed.

HSPs with childhoods that left them with these outdated rules—outdated in the sense that most people around them are not intending to criticize, reject, or attack them–are often very noticeable for their anxiety, depression, defensiveness, or their fear of defeat or rejection.  They may feel victimized, even for being HSPs. Plus, all this expecting the worst means even ordinary interactions can feel stressful for them.  (At least until they unlearn those conservative strategies in therapy or in healthier relationships or through enough success to make them feel socially secure.)

These HSPs who had difficult childhoods are visible above all for being stressed.  Of course, “high functioning” HSPs with good childhoods can be stressed, too, if their current environment is stressful.  But again, with their good-enough childhood, they can often avoid or at least manage brief stressful situations.

But It’s Not That We Must Have Good Childhoods–It’s That Our Sensitivity Prepares us for an Expectable Future

What most fascinates me, however, is that the trait is not about needing to have a good childhood in order to function well as an adult, but it is, again, learning so well from what we observe.  In particular it is about learning from our childhood environment what we need in order to survive in the assumed-to-be-the-same environment as an adult. If ever in doubt what SPS refers to, remember this study:

In a paper titled “Role of childhood adversities and environmental sensitivity in the development of post-traumatic stress disorder in war-exposed Syrian refugee children and adolescents” (rather than full citations, I am giving you what you need to find an article in Google Scholar), data from 549 Syrian refugee children in Lebanon was collected.  There were data on childhood adversities (neglect, abuse, fighting in the family, etc.) plus their exposure to war traumas (unable to leave home due to bullets and bombs, seeing people die or be tortured, etc.), the Highly Sensitive Child Scale, and an assessment of their degree of PTSD.

Although childhood adversities, war events, and sensitivity were all significantly related to PTSD, previous childhood adversities before the war were the most important variable in predicting PTSD.  But look at this: HSCs who had experienced lower childhood adversities had the highest level of PTSD.   Those HSCs with high childhood adversity experienced the least PTSD.  Here is the essence of SPS.  It seems that high childhood adversity prepared sensitive children in particular for the adversities of war, while a “good” childhood least prepared them.  So it was not having a good upbringing, but the match between earlier childhood and later events that led to the least stress and the best outcome, if we can call it that.  The trait does not make us fragile or stress-prone.  It is designed to prepare us for the life we will live in the future.

Research on Health Outcomes for HSPs

I promised to tell you about the actual research on health and SPS.  There are six studies that I know of.

In 2006 Benham found an association between SPS and physical symptoms—including back pain, diarrhea, heartburn, and sore throat—in American university students.In contrast, in 2016 Grimen and Diseth found in their study of Norwegian university students that there was no clear correlation between SPS and “subjective health complaints.” When they looked at the three factors found in the HSP Scale (more on that later) individually, they did find a relationship for two of the three, but the personality trait of neuroticism was a better predictor of having such complaints.Takahashi and others, in a 2020 study of SPS and “dispositional mindfulness” (the personality trait of being less reactive or judging of emotions, being able to describe feelings, and acting with awareness in the present) found that HSPs also having this trait reported fewer physical symptoms. Like Grimen and Diserth, they found the association with physical complaints only with two of the HSP subscales.Imura and Tagasugi (2022) used a large adult sample and tried to control for more socioeconomic variables (but not degree of stress) and found a low but statistically significant correlation between SPS and gastrointestinal symptoms, although they are very clear that correlation does not mean they know the cause of this connection.These four studies only looked at symptom checklists, not diagnosed illness.  A 2017 study by Goldberg and associates did consider a genuine illness and found an association between SPS and Type I diabetes in adolescence. However, this type of diabetes often begins when a youth is under stress.  So we are back to studying stress, and HSPs only indirectly.Finally, Benham (who did the first study above, in 2006) and his colleagues published in 2023 “The pathway from sensory processing sensitivity to physical health: Stress as a mediator.”  Looking for and finding a mediator is how you try to get at the causation, the source of a correlation, this time between SPS and health, and stress was the clear mediator.  It is what lies between SPS and health.

(In 2010 in Iran Ahad and Basharpoor found a relationship between individual factors of the HSP Scale and a variety of measures, including measures of health, but they never looked at the trait as a whole.)

Medical research is clear that stress is the biggest contributor to all health problems.  Because HSPs are affected more by their environment than others, including stressful situations, often made more stressful by lessons learned from stressful childhoods, in that sense HSPs are definitely more prone to any health problem that is increased by stress, including catching a virus because of a weakened immune system or spraining an ankle because of being too stressed to notice where they are walking!  But from the research so far, stress is the problem, not a direct connection between highly sensitive any particular illness.

The Difficulties in Studying SPS and Physical Health

HSPs whose health is severely compromised are sometimes surprised that there is not more research on how much more HSPs suffer from specific illnesses or general poor health compared to others.  Alas, it is a frustratingly big step from personal experience to research confirmation, but let’s understand it so you can understand future articles on the subject.

First, HSPs with a long history of stress are a subgroup of HSPs, so a good study must measure stress and see if HSPs are more prone to illnesses whatever their stress.  But that brings us to a second problem, even if you could know a person’s stress level, to establish that all HSPs are prone to a particular physical problem, one would have to get a nearly perfect sample of all types of HSPs from all over the world, all ages, all socioeconomic and education levels, and above all, the quality of childhood and general life adversities and advantages, in order to compare them to the incidence of the particular problem in the general population.  (Getting that is also difficult, but for some illnesses there would be data.)  It seems that in North America and Northern Europe, white males with advanced educations and loving parents who supported them in whatever interests they wanted to pursue, are quite different from HSPs not enjoying these advantages, and no doubt healthier than most of the population.  But it would be difficult to include them in a survey given that they may not even know they are HSPs.  Indeed, sensitive men generally score lower on the HSP Scale, even though there is evidence that they are as frequent at birth as HS girls.  A thorough sampling of HSPs would also have to include those who are illiterate or can read but do not have internet access.

Instead, you may find studies on the internet, probably not published in any reputable scientific journal, that only looked at the percentage of HSPs having an illness or chronic problem.  Perhaps they were the percentage coming to a clinic or subscribing to a newsletter for those with the problem.   The results were probably that some large percentage of those with the problem are HSPs.  With no comparison group, that means less than nothing—except that perhaps someone who is selling a treatment is trying to convince HSPs in particular that they need it.

Third, asking people about their health complaints or even lack of complaints fails to measure superior health.  But given differential susceptibility, to understand health and SPS one has to look at the vantage sensitivity side–for example, lower than average blood pressure or better sleep.  Many HSPs will not just lack problems, but be healthier than others, having been more attentive to prevention or to what is especially health-promoting for them personally.  They may even indicate the same number of problems or even more, being very attentive to their health, but also, overall, be healthier.  A study of HSPs and health must have a measure of better than average health.

Fourth, there is the problem of the measurement of SPS.  As I have said elsewhere, the HSP Scale is being revised.  It is good enough for many purposes, and was designed to measure only one thing, high sensitivity.  But if you force a questionnaire with many diverse items into a factor analysis (a statistical process of identifying clusters of items), multiple subfactors have to emerge, in this case Ease of Excitation, Low Sensory Threshold, and Aesthetic Sensitivity.  But a factor analysis does not work very well in this case.  The first two factors are almost identical and focus entirely on the problem of overstimulation.  The third, constituting only 7 of the 25 items, is not really about aesthetic sensitivity so much as that 6 of the 7 are the only items worded positively!  (A recent study looked only at the Aesthetic Sensitivity factor and health-related quality of life, but that is not really a study of SPS.)

In short, the current HSP Scale only minimally measures our response to positive stimuli, empathy, and depth of processing. With this bias towards the negative, people who are having a negative experience of being overstimulated will naturally score higher on the measure used in these studies, and these same HSPs are more likely to be under stress and report physical complaints, greatly adding to the association between SPS and physical problems.

Finally, but perhaps most important, being more sensitive to physical stimuli, HSPs are more likely to notice a physical sensation and register it as a complaint on checklists like those used in all but one of these studies.  Indeed, one of the items on the HSP Scale is about being more sensitive to pain. Those who are not HSPs may not consider the same level of problem as something to list as a complaint.  (“Yeah, my feet hurt.  No big deal.”)  Thus, from the perspective of a health professional deciding on a diagnosis, HSPs may not have more health diagnoses, but suffer more from the ones they have.

What About the Medication Study?

You may be wondering now about the problems that might be lurking in the study I mentioned in the newsletter on sensitivity to medication.  Of course, it is actually unrelated to health problems, since a person might be very healthy but still have noticed such a sensitivity.  But it is worth looking at the steps we took to avoid some of the actual problems.  About the issue of trying to get a representative sample of all HSPs, that was helped a tiny bit by using three separate samples—two of university students and one online.  In each case these were selected from a general population, not those thought to be HSPs, so the full range of SPS in at least those populations was hopefully included.

The HSP Scale’s limitations were still there.  But one would not expect stress and being overstimulated to affect very much being sensitive to medications, which is probably a more fundamental attribute.  A person might be very healthy and not stressed, but still know they are sensitive to medications.  Further, all subjects took a separate measure of negative affect so that being anxious, depressed, feeling stressed and so forth could be “partialled out” or “controlled for” statistically, and sensitivity to medications remained when that was done. HSPs being more sensitive to physical stimuli and pain is probably a major contributor to sensitivity to medication, but linking that sensitivity to medication was a reason for the study, not a flaw in it

Finally, a limit of this study is that it relies on self-report.  Still, it is a valuable step in deepening our knowledge of SPS, and HSPs can now cite research evidence when they explained to their medical professionals that they are more sensitive to medications.

Bottom Line: A huge amount of research indicates that the key to good health for everyone is reducing stress as much as possible.  That means that you as an HSP, by giving stress reduction your attention, can be healthier than others.  Yes, you get stressed by being overstimulated.  But you can figure out how to avoid that. You can meditate, make rest a priority, eat right, exercise, and set boundaries.  Stop listening to the news. Change jobs if you have to. Hire help.  Find a way.

If something is stopping you from reducing your stress level, it is probable that you had a difficult childhood.  Maybe you learned some bad habits as a child or, worse, you got the message from your caregivers that your physical well-being was not very important.  So do what you have to do to get over all that!

Maybe you are thinking of those Syrian refugees and that any adversity you suffered as a child should only make it easier to handle stress in adulthood.  But who wants to grow up prepared to deal with living in a war zone?  Most of us live in a very mixed world in which there is very little violence and ample opportunity to find meaning and some happiness if we can stay rested.

You cannot eliminate stress.  It is part of life.  But look around you at what stresses other people, and what stresses you in particular.  As an HSP it is your nature to observe your world and then use what you have seen to find a better way.  You can do that!