Why Do We Shed Tears When We Cry?

Medically Reviewed on 2/3/2022
why we cry the truth about tearing up
Researchers believe tears are a natural way for our bodies to relieve emotional pain, keep the eyeballs moist and healthy, and fight infection.

Most studies and researchers believe that tears are a natural way for our bodies to relieve emotional pain. Although many animals cry, it appears that emotional tears are a uniquely human experience.

Tears are required to keep the eyeball moist and contain proteins and other substances that keep the eye healthy and fight infection. Humans cry for various reasons, but emotional crying and crying in response to aesthetic experiences are unique to us.

Tears are good for your eyes, but they're also an important part of emotional and social communications. We don't know why we cry when we're upset, but we do know that chemicals found in emotional tears differ from those found in normal tears. According to some scientists, these chemicals may help us feel better after we cry.

Crying and tears are caused by lacrimal and limbic systems:

Lacrimal system

  • The lacrimal system is located next to your eyeball. It is both secretory and excretory systems that produce and drain your tears.
  • Crying tears are produced in response to strong emotions such as stress, pleasure, anger, sadness, and suffering, as well as physical pain.
  • These tears may even contain a natural painkiller called leucine enkephalin, which is why you may feel better after a good cry.
  • Crying is the scientifically shedding of tears in response to an emotional state, as opposed to lacrimation, which is the shedding of tears without emotion.
  • When we cry, we produce more tears than the eye can contain. This is due to the largest tear gland's ability to turn on and produce a large number of tears at once.
  • When this occurs, the eye can produce more than half a cup of tears in a matter of minutes. This is far too much for the lacrimal gland to handle at once.

Limbic system

  • The part of the brain that controls emotions sends signals to the part of the brain that controls tears.
  • The limbic system (specifically, the hypothalamus), which is hardwired into the autonomic nervous system (the part over which we have no control), is an area of your brain that deals with emotions.
  • This system has some control over the lacrimal tear system through a neurotransmitter called acetylcholine, and it is this tiny molecule that stimulates tear production.
  • In short, emotional reaction activates the nervous system, which then activates the tear-producing system.

Limbic and lacrimal systems collaborate to make emotional tears:

  • When we cry emotionally, the limbic system sends a signal to the pons (the brain's message station) that then sends a signal to the lacrimal system, leading to tearing production.
  • More research is needed to fully comprehend physiological and neural changes that occur due to emotional tears.

What does science say about tears?

Our eyes and brain can produce three different types of tears depending on the situation:

  1. Basal or basic tears:
    • These are the most common types of tears.
    • They contain oil, mucus, water, and salt, and they aid in fighting infections.
    • The oil holds tears in place and keeps them from evaporating into the air.
    • Blinking distributes them evenly across the surface of the eye.
  2. Irritant or eyewash tears:
    • They erupt from glands beneath the brows when you peel onions, vomit, or get dust in your eye due to the contraction of muscles in the tear gland.
    • They flush out irritants to keep your eyes clean.
  3. Psychic or emotional tears:
    • These tears flow due to strong emotions such as sadness, grief, joy, or anger.
    • They contain more stress hormones and natural painkillers than other types of tears.

Each tear comprises three layers:

  1. Inner mucus layer: Helps keep the tear attached to the eye
  2. Watery middle layer: Offers hydration and protection to the cornea and provides a shield against bacteria
  3. Outer oily layer: Helps the surface of the tear remain smooth and helps prevent evaporation

Tears are useful because they contain important proteins and immunoglobulins and play a role in eye defense. They have antimicrobial properties due to the presence of lactoferrin, and they wash away foreign substances from the eye.

Crying allows us to express our emotions and overcome sadness. Tear film contains major proteins and aids in the maintenance of visual acuity.


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What are the diseases caused by abnormal tear secretion?

Abnormalities of tear secretion cause various diseases; however, the three most important diseases include:

  1. Crocodile tears or Bogorad’s syndrome:
    • It is caused by improper nerve recovery in cases of Bell's palsy, in which people tend to cry while eating.
    • This is analogous to crocodiles secreting tears while eating, hence the name crocodile tears.
  2. Dry eye:
    • A dry eye is a symptom caused by a lack of tears.
    • Viral infection, excessive evaporation of tears, change in the composition of tears, and other factors such as old age and menopause may cause dry eye.
    • Humidifiers, artificial tear drops, moist chamber spectacles, tear replacement therapy, and good lid hygiene can help with dry eye management.
  3. Sjogren’s syndrome:
    • It is an autoimmune disease that affects the cells of the lachrymal gland, eventually resulting in xerostomia and keratoconjunctivitis.
    • It is more common in women than in men and usually occurs after menopause.
    • Other symptoms include muscle and joint pain, fatigue, and gland swelling.

Tears are a beautiful expression of who we are. It not only indicates our deep emotional links to our world's past, present, and future but also allows us to visibly celebrate that fact. They are scientifically proven to improve your mood, so go ahead and flaunt your tears with pride. 

If you are concerned that you are crying too much, too quickly, for no apparent cause, or have concerns about your mood, contact your doctor for a detailed evaluation.

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Medically Reviewed on 2/3/2022
Image Source: iStock Images

Why We Cry: The Truth about Tearing Up: https://www.webmd.com/balance/why-we-cry-tearing-up

All About Emotional Tears: https://www.aao.org/eye-health/tips-prevention/all-about-emotional-tears

Teary-Eyed Evolution: Crying Serves A Purpose: https://www.npr.org/templates/story/story.php?storyId=129329054

Why we cry: https://www.apa.org/monitor/2014/02/cry

What Brings a Tear to Your Eye? https://wonderopolis.org/wonder/what-brings-a-tear-to-your-eye