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Many things in this world cause intense sensations we perceive and feel. In my work as a physical therapist, much of this discussion surrounds sensory overload and assisting people in building up their ability to mitigate their responses to adverse sensory stimuli. But I want to speak to a less known sense, interoception. Interoception is the collection of senses that allows a person to tune in to what is happening inside their body; the body's ability to sense changes within itself. All of your organs send signals to your brain. Your body is in constant communication with your brain. How does this happen? Through interception.
Interoceptors include chemoreceptors, humoral receptors, specialized mechanoreceptors, and free nerve endings or nociceptors (1). These interoceptors send information from our organs, including our skin (the body's largest organ), to the central nervous system, which processes, interprets, and integrates this information. This is, of course, not a one-way channel. The brain doesn't just collect signals from the body; it sends signals that either modulate or intensify a response. This is why we can slow our heart rate through meditation and make our stomach ache with anxiety. We can amplify or mitigate pain by sending an area of the body signals of panic or breathing into the area of pain to release and minimize that sensation, all through a mere signal from the body to the brain AND from the brain to the body.
When we enter a sauna, the heat immediately intensifies our sensory experience. It further amplifies with the smell of the cedar, the sound of the crackling fire, and the water poured over the rocks, the way the steam burns in our nostrils and expands our lungs. The glorious trickle of sweat rolling down our skin, the heat of the benches. It can all be a bit much. Our body instantly sends information about how it is reacting to these inputs. While our senses of smell, sight, touch, and even taste may be the senses that we are most aware of in sensory-rich experiences like sauna, it is tuning inward to our sense of interoception that allows us to make further use of the physiological benefits of sauna.
By now, most of us have heard the vagus nerve come up in casual, non-therapeutic-focused conversation. It's a buzzword of sorts and deserves all the attention it gets. Concerning interoception, we currently understand the vagus nerve to be the body's main pathway for communicating what is happening within the body to the brain (2). The more we practice tuning in to our interoception and understanding our internal responses to internal and external stimuli, the better equipped we are to navigate the physical and psychological stressors of everyday life.
At times, tuning out physical or psychological pain can be protective. Ignoring fear can be adaptive. But a lack of interoception is indicated in various mental health struggles, including anxiety, depression, eating disorders, and even suicidal ideation.
When in the sauna, people often can't help but remark on the increased sensations they feel in their bodies. It's good to notice these things. Sauna is an opportunity to practice tuning in. Get to know your interoceptors, and you open a channel of communication from your body to your brain. Your body is speaking to you, and it serves each of us well to listen.
References:
1. Berntson GGB, et al. Neural Circuits of Interoception. This issue of Trends in Neurosciences. [PMC free article] [PubMed] [Google Scholar] [Ref list]
2. Backman, I. (2022, March 16). Revealing Communications Between Brain and Body. Yale School of Medicine. Retrieved July 3, 2023, from https://medicine.yale.edu/news-article/revealing-communications-between-brain-and-body/#:~:text=The%20body's%20ability%20to%20sense,by%20specialized%20vagal%20sensory%20neurons.
