Why do we cry?

Someone recently asked me, “Why do tears come out of our eyes when we’re sad?” It was such a simple question that I’d never really thought about. We cry because we’re sad, but why is it that we cry when we’re sad and not, say, hiccup?

Human eyes have 3 different types of tears: basal tears, reflex tears, and psychic tears. Basal tears are the tears that provide constant moisture for our eyes. They lubricate the eye with the up and down blinking of our eyelids. Reflex tears appear when an irritant is present and have the purpose of flushing the irritant out of the eyes. Reflex tears may result from dust in the air, cutting onions, or eating spicy food. The third type of tears, psychic tears, are associated with strong emotions and are secreted during crying.

Psychic tears are produced by the lacrimal gland, and the lacrimal gland is ultimately attached to the part of the brain that controls emotion. When certain receptors in the limbic system are activated by emotions, the lacrimal gland is stimulated and we cry. Psychic tears are chemically different than the tears our eyes produce to keep them lubricated. They contain higher levels of hormones, in particular corticotropin. Corticotropin is a hormone that is produced in response to stress. By crying, we are actually reducing stress hormone levels in the body through our tears. This is why many people feel calmer or more relaxed after ‘a good cry.’

On average, women cry about five times more than men (who cry about once a month). Some scientists say that humans aren’t the only ones who cry. There is evidence to suggest that our cousins the apes may also shed emotional tears!

“Unless you have been very, very lucky, you have undoubtedly experienced events in your life that have made you cry.  So unless you have been very, very lucky, you know that a good, long session of weeping can often make you feel better, even if your circumstances have not changed one bit.”  ~Lemony Snicket

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