The science behind tears

Years ago, I saw a grown man weeping silently on a subway car. No one asked him anything. No one wanted to know what lay behind those clear tears that fell as if trying to escape before he could. I was left wondering... if even the toughest parts of us can melt, what compels us to hold it back? Why do we cry, really? What's the point?

And no, the answer isn't "because we're sad." Science, as always, has an explanation for this, a much more complex, almost poetic story.

When the body decides to speak for itself

Crying is one of the most human reactions there is. We are the only species that produces emotional tears, not just tears to protect or moisturize the eye.

Crying is a mixture of biology, psychology, and something that belongs to the mystery of social life.

Three types of tears, three different purposes

Our body produces different tears depending on the situation:

• Basal : Lubricate and protect the eye 24/7.
• Reflexes : They appear when something irritates us (smoke, wind, onion...)
• Emotional : These are the ones that reveal that something emotional is happening inside us.

All three originate in the lacrimal gland , located above each eye. But emotional tears have a special chemical signature.

How is crying triggered?

Crying is a neurobiological reflex that originates in the brain, not the eyes. In response to intense emotion, the limbic system assesses the significance of the stimulus. The amygdala, a key structure in emotional processing, interprets the situation as significant and activates the autonomic nervous system.

This activation generates a descending signal via the facial nerve ( VII cranial nerve ), which directly innervates the lacrimal gland. In response, the gland involuntarily increases tear secretion.

The process does not depend on willpower or a conscious decision. It is an automatic response designed to express, regulate, and release an emotional charge that the nervous system considers relevant to the body's equilibrium.

We don't cry because we want to. We cry because our brain tells us to.

“What you feel… matters.”

It's a mechanism of the brain to communicate with ourselves, to make you realize that something is important, like a message to your future self a few seconds later.

Are all tears the same?

No. Although all tears are produced in the lacrimal gland, they don't all serve the same function or have the same chemical composition . The body produces different types of tears depending on the physiological or emotional context, and each type responds to a specific need.

From a scientific point of view, we can classify them as basal, reflex, and emotional tears . Furthermore, not all emotional tears are the same.

Basal tears: silent maintenance

Basal tears are present continuously. We don't notice them, but they are essential for eye health.

Their function is to lubricate the cornea, keep it transparent, nourish it, and protect it against infections. They contain water, electrolytes, lipids, and antimicrobial proteins such as lysozyme , which acts as a natural antibiotic.

Without them, vision deteriorates and the eye becomes vulnerable.

Reflex tears: immediate defense

Reflex tears appear when the eye detects a physical or chemical aggression: smoke, wind, dust, irritating gases, or onions.

Their purpose is not emotional, but defensive. They are produced in large quantities to dilute, carry away, and quickly eliminate the irritant. Their composition is similar to that of basal tears, but with a greater volume and a high concentration of defensive enzymes ( lysozyme , lactoferrin , and tear peroxidase ).

Emotional tears: regulation and communication

Emotional tears are unique to human beings. They are triggered by intense emotions such as sadness, fear, frustration, relief, or extreme joy.

Unlike the previous ones, they have a distinctive chemical composition and participate in emotional and social regulation.

Types of emotional tears

From a functional point of view, emotional tears can be differentiated according to the predominant emotion that causes them:

• Tears of sadness or loss
  Associated with grief, frustration, or emotional pain. They present elevated concentrations of cortisol and ACTH ( adrenocorticotropic hormone ), related to the stress response.
  
• Tears of relief
  They appear after the resolution of prolonged tension. They are associated with activation of the parasympathetic system and a progressive decrease in physiological stress.
• Tears of intense joy
  They arise in response to emotionally overwhelming experiences. They share mechanisms with crying due to stress, but with a positive emotional charge.

In all cases, these tears contain neuromodulators such as prolactin , endorphins , oxytocin , and proteins that act as social signals, promoting empathy and the response of the environment.

Comparative table of tear types

Tear type	Origin	Main composition	Function
Basal	Continuous production	Water, electrolytes, lipids, lysozyme	Lubricate, nourish and protect the eye
You reflect	Physical or chemical irritation	Water, defensive enzymes, lysozyme (high concentration)	Remove irritants
Emotional (sadness)	Negative emotional stress	Cortisol, ACTH, prolactin, proteins	Emotional regulation, stress relief
Emotional (relief)	Release after tension	Endorphins, oxytocin, prolactin	Physiological and emotional recovery
Emotional (joy)	Intense positive emotion	Neuromodulators and social proteins	Emotional regulation and social bonding

When we cry emotionally, the body not only expresses what is happening inside : it also adjusts its internal balance and communicates to the environment that something relevant is happening.

When we expel them, our stress level decreases . Literally, the body is draining suffering into fluid.

Physical reasons: crying to survive

On a physiological level, crying:

• It keeps the cornea clean and free of infections (thanks to lysozyme , a natural antibiotic).
• It adjusts tear pressure and ocular surface moisture.
• It activates the parasympathetic system , which calms the body after an emotional peak.

It's a way of resetting the nervous system. An emotional shutdown and reboot.

Psychological reasons: crying is language

Crying is also social communication in its purest form.

Before they can speak, babies only have two languages: smiling and crying . This is how they get protection and attention. As we grow older, we continue to cry because it works.
Tears evoke empathy and change the other person's behavior.

Crying says things that the mouth doesn't dare to utter:

• “I need help”
• “I’m at my limit”
• “This matters to me”
• “I can finally let it go”

Crying connects us. It makes the invisible visible.

Scientific advantages of crying

Although we sometimes feel it as a failure, crying is a very effective survival strategy :

Benefit	Mechanism
Reduce stress	Elimination of stress hormones + parasympathetic activation
It relieves pain	Release of endorphins and oxytocin
Improves sleep	Emotional regulation after crying
Strengthens social bonds	Biological signal of certain vulnerability
Improves eye health	Lubrication and antibacterial defense

Crying makes you human, but it also makes you healthier .

Why do we feel good after crying?

After intense crying, a familiar sensation often appears: physical exhaustion accompanied by mental relief. This is not suggestion or cultural custom. It has a clear neurobiological basis.

During emotional crying, the body transitions from a state of heightened arousal, dominated by the sympathetic nervous system and stress hormones, to a state of recovery. This shift is driven by the parasympathetic nervous system , responsible for calmness and repair.

At the same time, endorphins and oxytocin are released, substances that reduce the perception of pain and generate a feeling of safety. There is also a gradual decrease in cortisol , which contributes to the subjective feeling of relief.

From a psychological point of view, crying acts as an emotional release mechanism: it does not eliminate the problem that causes it, but it reduces the internal burden associated with it and temporarily improves emotional regulation.

When crying occurs in a safe or supportive environment, the effect is amplified. Tears also function as a social signal that fosters empathy and support.

Crying isn't just about tears: the body speaks too.

Crying is not just about shedding tears. It's a complex bodily response involving facial muscles, breathing, voice, and the nervous system. When we cry, the whole body is involved.

During crying, several facial muscles are activated in a coordinated manner: the brow furrows, the eyelids partially close, and the corners of the lips droop. This expression is universal and acts as a clear sign of vulnerability .

Breathing also changes. Short, deep inhalations are followed by long, irregular exhalations, which lead to sobbing. This pattern stimulates the parasympathetic nervous system , promoting a subsequent feeling of calm.

The voice becomes shaky or broken because the brain prioritizes emotional expression over fine motor control. It's not a lack of control, but a temporary reorganization of neurological resources .

Tears are only one part. The whole body sends the message.

Is it possible to cry on purpose? The case of actors

Yes, it's possible to cry on purpose, but not just any way. Genuine emotional crying isn't triggered by a direct conscious command, but rather through indirect pathways that the brain interprets as emotionally relevant. Professional actors don't "fake" crying: they trick the nervous system into activating it for real .

Activate emotion from within

The most effective technique is called emotional memory . It consists of recalling personal memories associated with sadness, loss, or intense relief. By reliving these experiences, the limbic system , especially the amygdala, is activated, triggering the same neurobiological circuit as in spontaneous crying.

From a brain perspective, there is no difference between vividly remembering something painful and experiencing it in the present. The body responds the same way.

Manipulating the body to activate the brain

Some actors use physical strategies to facilitate crying:

• Breath control , forcing irregular patterns similar to sobbing.
• Facial muscle tension , activating the muscles involved in crying.
• Reduced blinking , which promotes the accumulation of tears.

These techniques do not generate emotion on their own, but they lower the threshold for crying to occur.

Tears without emotion (and why they don't count)

There are purely mechanical methods, using irritants, that induce reflex tears. However, these do not activate emotional circuits , do not modify the voice or body language, and are usually not very believable on stage.

Therefore, in professional interpretation they are considered a minor resource.

So, is it real crying or faked?

From a neurobiological perspective, when an actor cries using emotional memory, the crying is real , even if the context is fictional. The brain does not distinguish between an emotion triggered by an external situation and one caused by an intense internal memory.

The difference lies not in the tears, but in the origin of the stimulus.

In summary:
One does not cry by direct will,
But it is possible to consciously activate the crying mechanism .

Why do children cry so easily when they don't like something?

In children, crying is not an exaggeration or a lack of self-control. It is a direct consequence of how their brain is structured.

During childhood, the emotional system (especially the amygdala) is highly active, while the prefrontal cortex , responsible for regulating impulses, frustration, and behavior, has not yet matured. This region does not fully develop until well into adolescence.

This means that when a child is faced with something they don't like—a refusal, a frustration, an unexpected change— they feel the emotion with full intensity , but lack the neural mechanisms to modulate it or put it into words.

Furthermore, crying is their most effective communication tool . Before mastering language and emotional regulation, crying is the quickest way to express discomfort, ask for help, or try to change their environment. From an evolutionary perspective, it works: crying elicits attention and a response from adults.

Unlike adults, children do not cry "over small things".
For their immature nervous system, that little thing is everything at that moment.

With brain development, emotional learning, and social experience, crying gradually loses prominence and is progressively replaced by language, negotiation, and self-control.

Why do some people cry easily and others almost never, even when sad?

The ability to cry is not a universal trait, nor is it evenly distributed. Whether one person cries easily and another hardly ever does, even when experiencing profound pain, indicates neither greater nor lesser emotional intensity . It is a result of a combination of biological, psychological, and social factors.

Differences in the nervous system

At the neurobiological level, there are individual variations in the reactivity of the limbic system and in the connection between it and the prefrontal cortex .
In some people, emotional arousal quickly translates into physical responses such as crying. In others, the prefrontal cortex exerts more intense control, modulating or inhibiting the outward expression of emotion.

Both patterns are normal.

Learned emotional regulation

Crying is also learned. From childhood, our environment teaches us when it is acceptable to cry and when it is not . People who grew up in contexts where crying was punished, minimized, or associated with weakness often develop an automatic inhibition of this response, even when the emotion is present.

It's not that they don't feel. It's that their system has learned to suppress it.

Emotional processing style

Some people process emotions in a more external and expressive way, others do so internally and cognitively .

• Those who cry easily tend to release their emotions more quickly.
• Those who do not cry tend to process it in silence, through thought, rumination or even the body (muscle tension, fatigue, insomnia).

Crying is just one way among many.

Hormones and biological differences

Hormonal factors also play a role. Prolactin and oxytocin , which are linked to emotional crying, vary between individuals and sexes, which can alter the threshold for crying. This explains why some people cry more easily without it necessarily indicating greater emotional fragility.

Is it bad to never cry?

Not necessarily. If the emotion is processed and regulated through other means, not crying isn't a problem. The risk arises when the emotion isn't expressed or processed , becoming chronic and manifesting as anxiety, somatization, or emotional exhaustion.

Feeling sad without crying is still feeling sad.

Not all brains process emotion in the same way.
Some do it in tears.
Others, in silence.

The absence of crying is not the absence of pain.
It's simply another way of managing it.

To learn more

If you want to delve deeper into the science behind crying and tears, these works offer a solid foundation from neurobiology, psychology, and human physiology:

• Vingerhoets, A.J.M. (2013). Why Only Humans Weep: Unraveling the Mysteries of Tears. Oxford University Press.
  A reference work on emotional crying, its evolution and its social function.
• Gračanin, A., Bylsma, L.M., & Vingerhoets, A.J.M. (2018). Why only humans shed emotional tears: Evolutionary and social perspectives. Human Nature , 29(2), 104–133.
  Scientific analysis of why emotional crying is unique to human beings.
• Frey, W. H. (1985). Crying: The mystery of tears. Minnesota Medicine , 68(7), 423–429.
  One of the first studies to describe chemical differences between emotional and non-emotional tears.
• Gross, J.J. (2015). Emotion regulation: Current status and future prospects. Psychological Inquiry , 26(1), 1–26.
  Key theoretical framework for understanding how crying fits into emotional regulation mechanisms.

These sources show that crying is not a system failure, but a complex biological response designed to regulate emotions, body, and social bonds.