This 'hidden' human sense can be crucial to studying mental health

[00:00:00]From very early on, we all are taught that humans have five senses. Sight, hearing, smell, taste, and touch. That is the answer we all learned in school.

[00:00:11]But scientists are now saying that this might be wrong. There is a whole sense running in the background of your body that almost nobody ever talks about. And new research suggests it might be one of the biggest hidden factors in our mental health. This sixth sense is called interosception.

[00:00:32]And by the end of this video, you're probably going to notice it everywhere.

[00:00:36]Hi, my name is Somia Pelle and welcome to another episode of Pure Science. So, what actually is interosception?

[00:00:44]Interception is your body's ability to sense and interpret what's happening inside it. Not the world out there, the world in here. your heartbeat, your breathing, whether you're hungry or thirsty or too hot or in pain, all that is being tracked constantly by a sense you probably never learned the name of.

[00:01:07]Psychologists Jennifer Murphy and Freya Apprentice, who study this at Royal Hol and UCL, explained this as a sense that makes sure every system in your body is running the way it should. But for a long time, that's basically all scientists thought interosception did.

[00:01:27]Housekeeping for your body, which means basically keep the body balanced, keep it alive. Nothing more dramatic than that. Researchers are now finding links between interosception and a range of mental health conditions, including anxiety, depression, PTSD, and eating disorders. The working theory is that the brain continuously reads internal signals like heart rate, muscle tension, and breathing for cues about whether a situation is safe or threatening. When that internal reading process is disrupted, it may contribute directly to these conditions. For example, a person with anxiety may become especially aware of their own heart rate during a stressful situation such as a job interview or a social event. That heightened awareness of a bodily signal can itself intensify the feeling of anxiety rather than simply reflecting it. There also appears to be a difference between men and women. Now, Murphy and Apprentice reviewed 93 studies on the subject and found that women on average performed less accurately than men on tasks measuring heartbeat awareness. The researchers suggest this could be one factor among several in why conditions like anxiety and depression become more common in women from puberty onwards. They are careful to note that the relationship is complex and not yet fully understood.

[00:03:06]The feeling of hunger offers another example. A study published this year in the journal Ebiio Medicine examined how hunger affects mood and found that people with more accurate interosception experienced fewer mood swings when hungry than those with less accurate interosception. This doesn't mean that they felt hunger any less. According to Nils Chromemer, a medical psychologist at the University of Tubingen and one of the study's authors, these individuals were simply better at keeping their mood stable despite it. Perhaps the clearest evidence comes from research on anorexia nervosa conducted by scientists at UCLA.

[00:03:52]For years, it was widely assumed that people with anorexia were consciously ignoring their body's hunger signals. To test this, researchers used an ingestable vibrating pill capable of measuring how accurately a person can detect sensations in their own gut. The results challenged that assumption.

[00:04:15]People with anorexia were not simply ignoring signals from the body, but their nervous systems appeared to process gut sensations differently, making those signals harder to detect, trust, and learn from. Notably, this difference persisted even after patients had restored a healthy body weight, which may help explain why symptoms can continue long after physical recovery.

[00:04:43]Now, not every scientist agrees on how to define interception or even whether it should be treated as a single unified sense. A paper published in frontiers in psychology led by cognitive scientist Felix Kohler of MIT argued that interosception may not exist as a single coherent concept at all, but rather on a broad label applied to several distinct and poorly understood processes. Other researchers such as Barry Smith of the University of London have proposed that humans may have as many as 30 distinct senses once the category is broken down further. So the scientific picture is still being worked out. What does seem clear, however, is that the body communicates with us far more than we typically recognize. A racing heartbeat or a sudden drop in mood when hungry may not be trivial background noise. These signals could be central to understanding conditions like anxiety and eating disorders. As the researchers here put it, a better understanding of what shapes our ability to sense our own bodies could eventually lead to improved treatments for a range of mental health conditions. If this topic feels personally relevant to you, particularly around eating or anxiety, it's worth remembering that support is available and speaking with a professional is a reasonable and helpful step. With this, we come to an end to this episode of Pure Science. I'm Somia Ple and you are watching this on the print.