Brain with neural pathways to pupil showing interconnected rhythms

Unlocking Your Body's Rhythms: Why Breathing Patterns Change During Mental Tasks

Soraya Malik in Mind & Education August 2025 • 4 min read.

"Discover how cognitive engagement impacts the connection between breathing and pupil dilation, affecting focus and stress levels."

Our bodies are constantly orchestrating a symphony of automatic processes, from the gentle rise and fall of our chest to the subtle adjustments in our heart rate. Respiratory sinus arrhythmia (RSA), the natural variation in heart rate that occurs with each breath, is a well-known example of this intricate dance. It's a sign of a healthy, responsive parasympathetic nervous system, often measured to assess our overall well-being. Similarly, our pupils, those windows to the soul, subtly dilate and constrict with each inhalation and exhalation, reflecting the interplay between our sympathetic and parasympathetic nervous systems.

But what happens to these rhythms when we engage our minds in complex tasks? How do our breathing patterns and pupil responses shift when we demand focus and concentration? Pupil diameter is modulated by cognitive processes via the locus coeruleus (LC) and prefrontal cortex and is used as an index of the cognitive or arousal state. A recent study has shed light on this fascinating question, revealing how cognitive engagement can override the body's natural autonomic control.

The study published in Respiratory Physiology & Neurobiology sought to investigate how respiratory-linked pupil fluctuations behave during cognitive tasks, challenging assumptions about autonomic stability under mental load. By understanding these shifts, we can potentially unlock new strategies for optimizing focus, managing stress, and enhancing cognitive performance.

The Cognitive Task Switch: How Mental Focus Changes Your Breathing and Pupils

Brain with neural pathways to pupil showing interconnected rhythms

Researchers at Hyogo College of Medicine and the National Institute of Physiological Sciences in Japan recruited healthy volunteers to participate in a delayed matching-to-sample (DMTS) task. This task required participants to memorize a sequence of visual figures and then identify matching figures after a short delay, testing their attention and memory. Throughout the experiment, the researchers meticulously measured the participants' pupil sizes, breathing patterns (through nasal airflow), and heart rate variability (R wave-to-R wave intervals, or RRIs).

The results revealed a fascinating interplay between cognitive engagement and autonomic control. During the delay period, as participants prepared for the task, both their pupil sizes and RRIs exhibited the expected respiratory fluctuations – pupils dilated during inhalation and constricted during exhalation, mirroring the rhythmic changes in heart rate. However, something remarkable happened during the discrimination stage, when participants actively focused on identifying the matching figures.

Here’s a breakdown of what the study revealed:

Respiratory fluctuations in pupil size vanished.
Heart rate variability remained linked to breathing.
Cognitive engagement led to increased pupil dilation.
The task revealed a cognitive state override.

The regular, breath-linked fluctuations in pupil size disappeared, while heart rate variability remained connected to the respiratory cycle. Furthermore, the more engaged participants were in the task (i.e., during successful matching), the more their pupils dilated. This suggests that the cognitive demands of the task triggered a control mechanism that overrode the usual respiratory-related autonomic regulation of pupil diameter. In essence, the brain prioritized focus over the body's natural rhythms.

What This Means for You: Practical Applications and Future Directions

This study offers valuable insights into the complex relationship between our minds and bodies. It highlights how cognitive engagement can influence autonomic functions, potentially impacting our ability to focus, manage stress, and perform optimally. By understanding these mechanisms, we can explore strategies to enhance cognitive performance and overall well-being.

About this Article -

This article was crafted using a human-AI hybrid and collaborative approach. AI assisted our team with initial drafting, research insights, identifying key questions, and image generation. Our human editors guided topic selection, defined the angle, structured the content, ensured factual accuracy and relevance, refined the tone, and conducted thorough editing to deliver helpful, high-quality information.See our About page for more information.

This article is based on research published under:

DOI-LINK: 10.1016/j.resp.2018.07.005, Alternate LINK

Title: Respiratory Fluctuations In Pupil Diameter Are Not Maintained During Cognitive Tasks

Subject: Pulmonary and Respiratory Medicine

Journal: Respiratory Physiology & Neurobiology

Publisher: Elsevier BV

Authors: Nozomu H. Nakamura, Masaki Fukunaga, Yoshitaka Oku

Published: 2019-07-01

Everything You Need To Know

How does focusing on mental tasks like the delayed matching-to-sample (DMTS) task change the connection between breathing and pupil size?

During demanding mental activities like the delayed matching-to-sample (DMTS) task, the usual respiratory-linked changes in pupil size disappear, but heart rate variability (RRIs) stays connected to breathing. The more someone focuses, especially when successfully matching figures in a DMTS task, the more their pupils dilate. This means that the brain's need to concentrate takes over the body's normal automatic control of pupil size.

What is Respiratory Sinus Arrhythmia (RSA), and how do pupils reflect the interplay between the sympathetic and parasympathetic nervous systems?

Respiratory sinus arrhythmia (RSA) refers to the natural variation in heart rate that occurs with each breath. It is an indicator of a healthy parasympathetic nervous system. When someone inhales and exhales, their pupils dilate and constrict. These changes reflect the interaction between the sympathetic and parasympathetic nervous systems. The study indicates that during cognitive tasks, cognitive engagement can override the body's natural autonomic control.

What is the delayed matching-to-sample (DMTS) task, and what measurements are taken during this task to understand cognitive load?

The delayed matching-to-sample (DMTS) task is used to evaluate attention and memory. In this task, people memorize a sequence of visual figures and then identify the matching figures after a short delay. During the DMTS task, researchers measure pupil sizes, breathing patterns (through nasal airflow), and heart rate variability (R wave-to-R wave intervals, or RRIs) to observe how these factors change under cognitive load.

How does cognitive engagement impact pupil dilation, and what parts of the brain are involved in this process?

Cognitive engagement impacts pupil dilation. Pupil diameter is modulated by cognitive processes via the locus coeruleus (LC) and prefrontal cortex and is used as an index of the cognitive or arousal state. During cognitive tasks, cognitive engagement can override the body's natural autonomic control. The study showed that during the discrimination stage of the DMTS task the pupils dilate more when participants were successful matching figures.

What are the potential practical applications of understanding how breathing patterns and pupil dilation change during mental tasks?

The study's findings can be applied to enhance cognitive performance, manage stress, and improve overall well-being. Understanding how cognitive engagement affects autonomic functions, such as breathing and pupil dilation, can lead to strategies that optimize focus and promote relaxation. Further research can build upon these insights to develop interventions for various conditions related to attention and stress.