Sigh Reflex Keeps Alveoli Inflated

Part of the reason we sigh is because the alveoli in the lungs collapse with disuse, and a sigh pops them back open by taking in more air, so humans average about 12 sighs an hour, and without them our lungs would fail. In 2016, UCLA and Stanford researchers showed that tiny clusters of neurons in the brainstem trigger these deep breaths to reinflate the alveoli, and when they blocked the relevant neuropeptides in mice, the animals stopped sighing, confirming how essential this reflex is for keeping lungs working.

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