The science behind why we cry

Why do we cry? [Photo: Getty]
Why do we cry? [Photo: Getty]

Hanger, ‘Queer Eye’ episodes, chopping onions and frustration are all likely to result in a proper blubfest.

Tears running down our cheeks is the ultimate external sign of sadness, but people cry for a whole slew of reasons.

It makes sense when babies cry. How else would they let you know they need their nappy changed or their tummy is right out of milk?

But, have you ever actually wondered why adults cry?

For many years, scientists have been baffled as to why grown-ups, who are fully able to express their feelings with words, still shed tears.

“It’s thought that tears cried in response to negative emotions, exist to signal our emotional distress to others,” explains Dr Jo Gee, women’s health psychotherapist at The Luna Hive.

“This happens because our ’emotional’ tears contain more protein and are thicker than tears in response to illness or pain, therefore making them more visible to others.”

In basic terms crying is a natural response humans have to a range of emotions, including sadness, grief, joy, and frustration.

But, if you delve a little deeper, the science behind a good old sob is actually pretty interesting.

What happens to the body when we cry?

Actually, quite a lot.

“When we cry, the diaphragm pulses, moving strongly up and down,” explains Claire Dale and Patricia Peyton, authors of Physical Intelligence.

“This stimulates our vagus nerve to trigger the release of acetylcholine, the chemical that brings us back into balance (homeostasis). Cortisol (anxiety) levels drop, serotonin (happiness), oxytocin (belonging) and dopamine (pleasure) levels rise, physical tension dissipates and we feel ‘relief’.”

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The body makes three different types of tears

According to Elizabeth Hawkes, Consultant Ophthalmic and Oculoplastic Surgeon at the Cadogan Clinic our body makes 3 different types of tears.

“Basal tears which are in our eyes all the time and lubricate and nourish the ocular surface,” she says. “Reflex tears are released in response to an irritant, such as smoke fumes or the fumes released when cutting an onion. Emotional tears are released in response to a strong emotion such as a sadness, joy or pain.”

We can’t control when we cry

That’s because the signal to produce emotional tears or ‘crying’ is under the control of our autonomic nervous system.

“This system is responsible for our functions not consciously controlled, such as heart rate,” explains Miss Hawkes.

“An emotional trigger stimulates the amygdala and hypothalamus (parts of the brain) which send a direct response to our lacrimal gland. This explains why we can’t control when we want to cry! Interestingly, humans are the only species thought to be able to able to produce emotional tears.”

Women cry more than men, and for longer [Photo: Getty]
Women cry more than men, and for longer [Photo: Getty]

Women cry more than men

According to biochemist William H Frey, who studied the subject of crying during the 1980s, women cry five times more often than men.

Further research on Adult Crying from clinical psychologist Professor Ad Vingerhoets found that on average, men cry between six and 17 times a year, while women cry between 30 and 64 times.

Crying bouts usually last six minutes for women and between two and four minutes for men.

Experts believe this crying gender divide could be down to the hormone prolactin, which is associated with the prompting of tears and is found in higher concentration among females. But men also have bigger tear ducts, so tears are less likely to escape their eyelids.

Crying makes us feel better

That calming feeling we get after a good blub? Experts believe that could very well be down to the neurotransmitter leucine enkephalin, which is emitted when we cry and happens to be a natural painkiller.

“Tears can be a great tool for communication, as well as processing emotion,” explains Dr Gee. “After crying, our brain released endorphins called leucine-enkephalins, which soothe pain and bring about a sense of relief and calm. Psychologists find that crying in sessions, often brings about therapeutic benefits, and a rise in mood.”

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Why else do we cry?

According to Sundeep Vaswani, Consultant Ophthalmic and Oculoplastic Surgeon at the Cadogan Clinic tears can also occur as a result of blockage of the tear drainage system, called the lacrimal apparatus.

“This can be an age-related problem but can sometimes even affect young children in the first year of life when the lacrimal apparatus is not yet fully developed.

“Rarely it can be caused by more serious problems such as tumours that cause compression of any part of the lacrimal apparatus. It is therefore important to seek advice if watering of your eyes is persistent or troublesome,” he adds.

What are crocodile tears?

The term crocodile tears originated from the belief that crocodiles cry when eating their victims and therefore was thought to be sinister.

“This gives rise to the social labelling of an insincere cry,” explains Miss Hawkes. “However, as described above, crocodiles probably do not produce emotional tears, but they are likely to be basal and reflex in origin.”

“In medical practice, we use the term ‘crocodile tear syndrome’ for something quite different. These tears occur following recovery from facial nerve damage (e.g. after a stroke). The facial nerve is the motor nerve which controls the muscles of facial expression and salivation. When it has been damaged, sometimes during nerve recovery, a process called aberrant regeneration can result in an abnormal wiring between the facial nerve and the lacrimal gland.

“This malfunction causes an unusual symptom of excessive watering (simulating crying) triggered by eating. Crocodile tear syndrome can be treated with botulinum toxin injections directly to the lacrimal gland which reduces the production.”