#Visionresearch

In a revolutionary discovery, researchers from the Karolinska Institute in Stockholm and the University of Groningen have found that our pupil size changes in harmony with our breathing pattern—a phenomenon now known as the “pupillary respiratory phase response.” This cutting-edge research, recently published in the Journal of Physiology, adds a new dimension to our understanding of the body’s internal rhythms, revealing a connection that could have significant implications for both vision science and medical diagnostics.

Researchers at the Karolinska Institute in Stockholm and the University of Groningen report a surprising link between how we breathe and how our pupils adjust. The study introduces the pupillary respiratory phase response, a phenomenon where pupil size changes with each breath. Published in the Journal of Physiology, the work adds a new layer to our understanding of the body’s rhythms and could influence vision science and medical diagnostics.

Traditionally, pupil size is known to respond to lighting, focus, and mental effort. The new findings show breathing as a fourth trigger. Pupil size tended to be smallest during inhalation and largest during exhalation, a pattern observed in more than 200 participants across different lighting, breathing methods, and cognitive tasks.