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Monday, May 30, 2016

The Science of Tears

Originally Published: May 30, 2016
Written by: Malvika Agarwal

When was the last you cried? Maybe it was while you were watching a sad movie or when a loved one was leaving you or because you just felt lonely. The next thing you know, you have a lump in your throat, your eyes start to water and tears are running down your cheeks. Considering that crying is an important and common part of everyone's lives, many of us know surprisingly little about it.

What happens when we cry, exactly? While the lacrimal gland produces a watery component, the glands in our eyelids produce an oily component, and other cells produce mucus. These mix together on the upper, outer region of your eye to create a film, which covers the white of the eye and the cornea. When we blink, the film is wiped across the eye by the eyelids. This fluid, better known as tears, drains into the tiny openings in the eyelids, called puncta (one on the inside corner of each lid), and then through ducts to the nasal cavity, where they either become part of nasal fluid or are swallowed. This is why we also get "stuffy" when we cry. If insufficient tears are produced or the constituents are out of balance, it can result in sore, dry eyes.

Over the years, many scientists have researched on how humans cry. Ad Vingerhoets, a professor of psychology at Tilburg University, discovered that there are 3 types of tears. The first type is basal tears, and they lubricate and protect the eyes at all times from damage by incoming air currents and floating debris.

Often, people tend to cry when they are cutting onions. These types of tears are called reflex tears, which are produced when the eyes make contact with wind, sand, insects or rocks. Reflex tears protect the eyes from irritants such as wind, smoke, and chemicals. They also help flush out random specks of dirt or any object that gets into the eye.

The last types of tears are emotional tears, which are secreted in moments of intense feeling - sometimes joy, but more often sorrow. These tears ears are produced in such large quantity that they overflow and fall down our cheeks. This type of crying occurs in response to stress, frustration, sadness, and happiness, and any other motion that evokes tears.

It has been statistically proven crying is beneficial for the health of individuals. Studies show that holding your emotions in can be dangerous over the long-term. In fact, some research indicates that stifling emotional tears can cause elevated risk of heart disease and hypertension. Other studies have shown that people suffering from such conditions as colitis or ulcers tend to have a less positive attitude about crying than their healthier counterparts. Psychologists recommend that people suffering from grief express their emotions through talking and crying, rather than keeping their emotions in check. Many studies also show that women cry 5.3 times a month, while men only cry about 1.3 times a month on an average. The reason is that men produce testosterone, which prevents them to tear up. On the other hand, women have lots of prolactin (a protein found in the body), which stimulates tears.

Tears of joy and tears of exhaustion. Tears of a clown or crocodile tears. Tears caused by chopping onions and death of a loved one. In the end, a tear is a tear, and they help protect and preserve the condition of our eyes. Crying might make your eyes red and puffy, but they won't affect your eyesight. So the next time you have the temptation to cry, go all out! 


Duffin. C. Why do we Cry Tears of Joy?. TMG [Online] 2014, 4.3,22-25.

Mikulak, A; Aragon, O; "Tears of Joy" May Help Us Maintain Emotional Balance. PSA. [Online] 2014, 2.1, 30-35.

Oaklander. M. The Science of Crying. TSA [Online] 2016, Version 4.2, 3-10.

Oskar, S. Why do we cry?. CPJ [Online]. 2013, Version 1. 60-69

Popova, M. The Science of Why We Cry and the Three Types of Tears. [Online] 2012,107, 4-5.


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