Interoception

We perceive the outside world through our eyes and ears and feel the texture of objects with our fingertips. This reception of external stimuli is called exteroception. The sense of the position and movement of our joints and muscles is called proprioception. Interoception adds a third dimension: sensing the body's internal state.

Here are some things we feel through interoception.

• The feeling of the heart beating quickly or slowly
• Feeling out of breath or breathing comfortably
• Hunger, thirst, and fullness
• The urge to urinate or have a bowel movement
• Nausea or changes in body temperature, such as feeling warm or cold

These signals originate in sensory nerves throughout the body and travel up to the brain along several pathways, including the vagus nerve. The brain brings these signals together to interpret "what state my body is in right now." A brain region called the insula is known to be deeply involved in this process.

Interoception works together with the autonomic nervous system. When you feel tense or anxious, the sympathetic nervous system becomes more active, making your heart beat faster and your breathing shallower. Noticing these changes is interoception. Conversely, when you feel at ease, the parasympathetic nervous system becomes dominant, your heart rate and breathing settle, and you also experience that ease through sensations inside your body.

This is why interoception is closely connected to emotions. A pounding heart, a tight feeling in the abdomen, and stiff shoulders often accompany emotions such as tension or worry. Noticing your body's signals can help you understand your current state. Bodily sensations can provide clues to interpreting emotions. This connection also extends to the pain–emotion interaction.

Interoception varies from person to person. Some people readily notice their body's signals, while others only notice hunger or fatigue much later. Researchers also examine interoception in several distinct dimensions. For example, how accurately you detect your actual heartbeat and how sensitive you feel you are to your body's signals are different aspects.

When life is busy or stress continues, it is easy to miss your body's signals. Conversely, when pain persists, those signals can feel stronger and more threatening. At such times, calmly observing the sensations in your body can help.

Breathing is one of the most accessible pathways to interoception. Because breathing is both an autonomic function and something you can consciously control, it offers an entry point for sensing the inside of your body.

Research suggests that breathing slowly, particularly with longer exhalations, as in slow breathing with prolonged exhalation, produces changes in heart rate variability and parasympathetic nervous system activity. The size and duration of these changes vary from person to person. Relaxation training, mindfulness, and biofeedback are all ways of paying attention to your body's signals and practicing self-regulation of tension and arousal.

With practice, you can become better at sensing signals from inside your body. Start with something simple.

• Feel your breathing — Sit comfortably and observe the air moving in and out through your nose and the rise and fall of your abdomen and chest for 1–2 minutes. You do not need to change anything; just notice it.
• Feel your heartbeat — After climbing stairs or doing some light exercise, feel the beating in your chest or the pulse at your wrist. Also notice how it gradually settles as you rest.
• Eat slowly — Chew each bite slowly, noticing how hunger subsides and the feeling of fullness builds.
• Body scan — While lying down, move your attention from your toes to your head in sequence, noticing where you feel warmth, heaviness, or aching stiffness. This method is often used in mindfulness and meditation.
• Name your body's state — Briefly put the sensations you feel right now into words, such as "My shoulders are stiff" or "My abdomen feels tight."

If discomfort feels intense or anxiety rises while you focus on your body's signals, pause, open your eyes, and look around. It is enough to proceed only as far as feels comfortable.