Scientists reveal what is actually happening to your body when you let out a random sigh - PsyPost

What the report says

PsyPost reported on July 26, 2026, that a study in the journal Psychophysiology suggests spontaneous sighs may serve a regulatory function during long, repetitive tasks rather than simply signaling boredom or frustration. The research, by Ralph W. G. Andrews, Michael C. Melnychuk and Paul M. Dockree, examined whether occasional deep breaths help stabilize breathing patterns and influence physiological arousal while people sustain attention.

According to the report, the researchers analyzed two datasets. In one, 72 adults completed a visual attention task across repeated eight-minute blocks while their thoughts, breathing and pupil size were monitored. In another, 57 participants performed a rhythmic listening task for 21 minutes; some breathed normally, while others were told to coordinate breathing with the sounds. Sighs were identified as breaths at least twice as deep as a participant’s average breath, using a belt around the lower chest, while eye-tracking cameras measured pupil changes.

PsyPost said the team found that normal breathing became more irregular over time during monotonous tasks, and sighs tended to be followed by a return to more organized breathing variability. Participants instructed to breathe slowly and deliberately sighed far less, suggesting controlled breathing can reduce the body’s tendency to produce spontaneous deep breaths. The study also linked sighs to a brief, timed dilation of the pupils, which the researchers treated as a sign of changing alertness.

The findings matter because they point to sighing as part of the body’s automatic regulation system during sustained attention. However, PsyPost noted important limits: the equipment could not distinguish sighs from yawns, the tasks were relatively easy, and the study did not find immediate improvements in reaction time or self-reported focus after a sigh.