Tears of happiness flow from our eyes when we are filled with overwhelming feelings of joy elevation or gratitude. Although crying is usually associated with distress experiences that are particularly positive such as receiving an award a marriage proposal or watching an emotional movie may also cause people to shed tears.
In other words crying happens when we are emotionally overwhelmed and exceed our capacity to contain feelings even if the emotions are positive.
Tears are the most prominent feature of crying.
Our eyes secrete tears constantly to protect the eye layer from foreign agents these are called basal tears and they drain into the nose continuously without spilling from the eye.
The increase in tear production as a form of emotional expression is considered unique to humans but recent research measuring tear increase in dogs when meeting their owners again compared to meeting another familiar person challenges this claim.
Moreover crying is not only tears but also sounds of sobbing and breathing contortions also expressed in animals.
In any case at least among humans crying is a universal experience therefore many researchers have tried to decipher why we cry from happiness
Crying is healthy because it creates emotional and physical relief.
The body always strives to return to baseline levels in all physiological and emotional measures.
Our emotions and certainly strong positive emotions that cause us to cry from happiness may disrupt this balance by increasing heart rate and blood pressure and also affecting our breathing rate.
The heightened arousal in the body is regulated by the autonomic system composed of two subsystems that act oppositely the sympathetic system and the parasympathetic system.
The sympathetic system is mainly active in emergencies when we are alert preparing us for action. Therefore during sympathetic activity heart rate increases blood pressure rises and breathing is short and fast.
In contrast the parasympathetic system is active during rest or relaxation.
Various studies have shown an increase in sympathetic activity such as higher heart rate and skin conductance before crying.
But the most important point is that after crying the balance between sympathetic and parasympathetic activity returned to baseline levels.
Therefore it seems crying is one of the ways the parasympathetic system suppresses sympathetic activity and returns the physiological system to balance
Tears are produced in a gland above the eyelid on the left and drain into the nose through ducts on the right.
Increased tear production as an expression of emotion is a universal and almost unique phenomenon to humans
Relief Burst
The area in the brain responsible for emotional expressions like crying is located in the brainstem and is called the periaqueductal gray PAG.
The cells in this PAG area get input from our emotional system the limbic system and then execute a motor plan appropriate to express emotions such as laughter and tears of joy.
Each component of crying whether sounds produced muscle contractions breathing contortions or tears may help with relief in different ways.
For example we demonstrate how the systems balance through the tear component.
When we cry from happiness tears are produced by lacrimal glands located near the eye sockets. There are nerve endings that innervate the glands thereby activating or suppressing them.
The nerves controlling gland activity belong to the sympathetic and parasympathetic systems but it is the parasympathetic nerves related to relaxation that encourage tear production.
In contrast the sympathetic system suppresses them.
The parasympathetic system encourages tear production to reduce the heightened arousal accumulated earlier from sympathetic activity
Is there something in the tears themselves that causes relief?
Among other things parasympathetic activity causes the release of acetylcholine in the tear gland responsible for releasing some of the substances composing tears. The composition of tears secreted due to intense emotion differs from basal tears secreted continuously to protect the eye.
Emotional tears contain electrolytes and various proteins including hormones and other substances that influence mood.
Thus tears help release chemicals as part of the experience of physiological emotional discharge
One substance found in high levels in tears is cortisol a hormone associated with stress.
The hypothesis was that crying helps remove excess cortisol from the body.
To test this experiment women watched an emotional movie hoping it would bring them to tears and cortisol levels in their blood were measured before and after the movie.
In women who cried during the movie blood cortisol levels were lower after the screening than in women who did not cry.
The conclusion was that crying helps reduce stress and return the system to balance
Additionally there are hypotheses that crying involves other factors that positively influence mood. For example oxytocin the love hormone generally known to increase relaxation and lower cortisol levels.
Most studies show its importance in response to someone else’s crying especially in parenting context but few studies examined its direct link to crying.
However it was found to be involved in parasympathetic system activity and recently research in dogs showed it is involved in increasing tear secretion.
There are also findings showing that during crying or laughter there is increased release of endorphins natural substances produced in the brain creating a feeling of euphoria
What is in the tears?
Apparently substances in tears affect not only us but also other people.
Research collected tears resulting from sadness in women and examined their composition and effects on men.
They found that tears from sadness reduced sexual desire and testosterone levels in men.
Therefore it can be assumed that there is a chemical composition difference between tears of sadness and tears of joy.
Indeed recent research found that composition differs between basal tears sad tears and happy tears. This may be part of the mechanism where tears serve as a means of communication between people. Findings regarding the chemical composition of tears align with psychological studies showing that we use crying to recruit others for social support and to encourage empathy and closeness. Additional studies reinforced this by showing people cry more in the presence of others than alone
A small study measuring brain activity in humans during buildup and release of crying shows synchronization between the central nervous system and the autonomic system.
Researchers used near infrared spectroscopy measuring changes in blood oxygenation an indirect measure of brain activity since active neurons consume more oxygen.
Eight participants watched an emotional movie until tears and during viewing researchers measured oxygenation in their brain.
Before the start of crying there was a gradual increase in medial prefrontal cortex mPFC activity an area linked to emotional regulation.
At the same time heart rate increased reflecting emotional flooding and sympathetic system activity. Immediately at the onset of crying a sharp increase in prefrontal cortex activity was observed signaling the transition from sympathetic to parasympathetic activity.
After crying participants reported higher clarity compared to those who did not cry supporting the hypothesis of parasympathetic activation
In the end crying from happiness is the way our body copes with waves of intense emotions and regulates them in a way that promotes our mental wellbeing.
Therefore next time you feel tears rising let them out.
The body knows what it is doing