Interoception: The hidden ‘sixth sense’

“See, hear, smell, taste, touch… With our five senses, we can learn so much!” You’ve probably heard some variation of this nursery rhyme. Most languages have their own version, walking kids through each of their senses. But those songs paint an incomplete picture of our sensory system, for they only include our outward-facing senses, which scientists call exteroception (literally, “external perception”).

We also have an internal sensory system that allows us to perceive and interpret signals originating from within the body — such as your heart, stomach, or lungs. For instance, you may feel hungry, sense your heartbeat increasing, or notice the air in your lungs. This process through which your nervous system maps your body’s internal landscape is called interoception.

Interoception is how we understand our body’s inner sensations. It’s our brain’s ability to sense what’s happening inside the body and adjust accordingly. And recent research suggests that this sixth sense may play a key role in our well-being and even our sense of self.

Interoception – Ness Labs Illustration

Making Sense of The Sixth Sense

People usually think of the brain as an organ designed to respond to external stimuli. Let’s say you’re in the kitchen, heating a pan of oil to fry some food. When you drop a piece of food into the pan, the heated oil splatters. You feel a few hot droplets hitting your skin and reflexively pull your hand away to avoid further splashes.

Now, imagine reading this in a cookbook: “When adding food to hot oil, especially those with high moisture content like fresh fish or certain vegetables, always do so cautiously to prevent dangerous splattering.” A weird thing may happen: simply reading this cautionary advice might make you experience the burning feeling of the hot oil droplets!

You’ve probably experienced something similar when a friend tells you a story and you get goosebumps, or when you wince when someone recounts an accident, or when watching a movie where someone is on the edge of a tall building and your palms get sweaty or your stomach is churning.

That’s because our brains didn’t evolve to merely react to the world around us, but rather to try to predict what will happen to us next based on both external and internal signals. This predictive process is how your brain makes sense of the world and guides your actions.

In addition to your five other senses, interoception is crucial to this predictive process. Interoception is how your brain integrates information about the body’s internal state. It helps the brain keep your body in homeostasis — continuously adjusting many variables such as your temperature and blood pressure to maintain the equilibrium that’s best for your survival.

The Five Fundamentals of Interoception

Interoception is an emerging topic of research that fascinates neuroscientists, including myself. Here are five things you need to know about how this sixth sense works:

1. Interoception can be conscious or subconscious. Interoception includes the processing of signals such as the rate of your heartbeat, your breathing, and whether you’re full or hungry, among many others. We perceive many of these sensations unconsciously, but some make their way into our conscious awareness. This conscious processing of our internal signals is known as interoceptive awareness.

2. Many factors shape our interoceptive abilities. Traumatic experiences can affect interoceptive awareness, either dulling or heightening your sensitivity to your internal experience. Our day-to-day environment, which includes factors like stress, dietary habits, and overall health, also has a significant impact on our capacity for interoceptive awareness. For instance, researchers explain that “we are currently exposed to an excess of exteroceptive stimuli for food consumption, marked by the high availability of a wide variety of ultra-processed and hyperpalatable foods, in addition to increasingly larger food portions that end up intensifying the reward responses and circumventing the homeostatic balance mechanisms.”

3. Interoception deeply influences both mental and physical health. Research suggests that a higher degree of interoceptive awareness has been linked to enhanced mental health, while lower interoceptive awareness is associated with several mental disorders. For instance, people suffering from depression may have a reduced ability to perceive bodily signals, which may contribute to emotional numbness. People with anxiety may be hypersensitive to cues from their own bodies, leading to exaggerated responses. This disconnection between what the body feels and how those signals are acted upon has also been found to be central to eating disorders like anorexia or bulimia.

4. Interoception can go awry. Being aware of our body’s internal signals is helpful, but we shouldn’t always use them to guide our decisions. For instance, in a study of decision-making and interoception, participants’ heart rates were monitored while they engaged in a gambling task. They were asked to identify profitable card decks. Interestingly, those with more accurate interoception aligned their choices with cardiac activity. But choosing a deck in response to an increased heart rate was a double-edged sword. If their heart rates surged when they picked a bad deck, these people fared worse than those with lower interoceptive awareness.

5. Interoception can be trained. Interventions focusing on enhancing interoceptive awareness are still in their early stages but show promise. One recent study looked at autistic adults, a demographic known to be at increased risk for anxiety. Participants were trained using heartbeat detection tasks, receiving feedback on their performance. The results were striking: those trained in interoceptive awareness exhibited a significant reduction in anxiety rates compared to the control group. Simply put, being able to tune into their inner states helped them de-catastrophize them more effectively.

Now that you know the five fundamentals — and you are hopefully convinced of the usefulness of mastering your sixth sense — let’s move on to some more practical insights.

How to Practice Conscious Interoception

We have established that better interoceptive awareness is linked to better mental and physical health. But how the heck are you supposed to improve your interoceptive awareness?

There are countless articles that have been published on the topic, but I’ll distill some of the most immediately applicable strategies you can start using right now.

First, you want to know where you stand in terms of interoceptive awareness. One simple exercise is to count your heartbeat in your head for over a minute and then compare it with the actual reading.

You may want to use a Heart Rate Variability (HRV) tracker — most smartwatches have one — or you could do it the old-school way by asking someone to count your heartbeats by placing their index and middle fingers on your wrist, at the base of your thumb. The second method is not as accurate but can be a good way to get started.

You can also fill out the Body Perception Questionnaire, which has been translated into many languages. You can download a version in English here. This is not necessary, but knowing your baseline score will allow you to track your progress over time.

Next, let’s have a look at three simple exercises that can help you improve your interoceptive awareness:

  • Body scanning. This involves mentally scanning your body from head to toe. Just sit down in a quiet space, and spend a few minutes noting sensations, tensions, or discomforts in each part of your body. Is your throat itchy? Does your chest feel tight? Over time, this will help you become better at recognizing your bodily signals.
  • Interoceptive journaling. Taking a few minutes daily to jot down internal sensations and emotions can help you create a habit of tuning in to the body’s signals. You can even incorporate this into your existing journaling practice. Here is a list of questions you can use for interoceptive journaling.
  • Interoceptive exposure. This one consists of intentionally placing yourself in situations that elicit stronger physiological responses and practicing noticing and labeling the corresponding internal sensations. You can start with simple ones, like brief cold exposure or safe cardiovascular exercise, and ramp it up to more challenging situations, like public speaking.

In addition to these three simple exercises, any mindfulness practice would probably help increase your interoceptive awareness (though of course not all have been thoroughly researched yet). That includes meditation, breathwork, and yoga.

That’s it, folks! As with most tools that can help you live better, it takes time and dedication to unlock some of the most impactful benefits of better interoceptive awareness. But even if you only do one of those exercises for a little while, you’ll find that it helps you become more aware of and able to regulate your emotions.

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