JUL 13, 2021 7:26 PM PDT

The Science of Crying

WRITTEN BY: Alexandria Bass

Crying: In humans, it is the production of tears usually accompanied by facial muscle contractions and vocal sounds. But what happens in the body during this ordinary occurrence, and what social significance does it have?

According to research in the journal Human Nature, the connection between vocal sounds, facial contractions, and tear production during crying is hypothesized to form in infancy. Contractions of eye muscles associated with distress vocalizations are thought to stimulate sensory nerves of the cornea to trigger the lacrimal glands and release tears.

From a broader physiological perspective, crying is associated with activation of the sympathetic and parasympathetic nervous systems, branches with opposing effects. The sympathetic nervous system activates the fight or flight response to release adrenaline to increase heart and respiration rates, while the parasympathetic nervous system promotes rest and relaxation by slowing both. Sympathetic activity increases before crying and returns to baseline shortly after, while parasympathetic activity remains increased for some time after the onset of crying. The tear-producing lacrimal glands are innervated mainly by the parasympathetic nervous system. Increased parasympathetic activity may be responsible for reports of improved mood after crying.

Activation of the nervous system stems from the activation of several brain regions in the central autonomic network that includes parts of the cerebrum, such as the limbic system, the diencephalon, and the brainstem. Connections between the cerebral cortex and the brainstem, such as the cortico-bulbar tract and the fronto-limbic-pontine-medullary pathways, are responsible for linking emotions to facial expressions and vocalizations associated with crying.

Because of gender discrepancies in crying frequency, hormones are also thought to influence the physiology of crying. Women cry 2 to 4 times more often than men. Researchers suspect testosterone may explain the difference – testosterone is thought to inhibit crying, with evidence from studies examining castrated males and men on medications that block testosterone.

Gender has also been found to affect our perceptions of crying, as mentioned in research in Emotion Review. Male criers were evaluated more negatively than female criers, with crying males often seen as weak and less competent. Female criers elicited more sympathy and comfort. Male observers responded more negatively to criers in general, while female observers were more likely to cry along with the crying individual.

Personality also influences reactions to crying, as examined in Frontiers in Psychology. Extraverts report more relief from crying, perhaps because they are better able to elicit social support from it. More conscientious people report more negative effects from crying, associating it more often with feelings of guilt and shame. More neurotic and more empathetic individuals cry more frequently in general. And depressed individuals may experience an inability to cry.

Sources: Clin Auton Res, Front Psychol, Emot Rev

About the Author
Bachelor's (BA/BS/Other)
Alexandria (Alex) is a freelance science writer with a passion for educating the public on health issues. Her other professional experience includes working as a speech-language pathologist in health care, a research assistant in a food science laboratory, and an English teaching assistant in Spain. In her spare time, Alex enjoys cycling, lap swimming, jogging, and reading.
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