Think about the last time your eyes watered. Maybe you were slicing an onion. Maybe a song came on the radio that reminded you of someone you miss. Either way, the result looked the same: a few salty drops rolling down your face. But were they really the same tears?
Not quite. Scientists sort tears into types, including basal tears that keep your eyes moist, reflex tears that wash out irritants, and emotional tears. Their makeup differs. Emotional tears have been found to contain higher levels of certain stress-related hormones and a natural painkiller than tears caused by onion fumes or dust. Why that is, and what it means, is still debated.
Three Jobs, Three Kinds of Tears
Most of the time, you don't notice your tears at all. Basal tears trickle out constantly, at a tiny rate, to keep the surface of your eyes lubricated. Every blink spreads a fresh film across the eye.
Reflex tears are the emergency crew. When something irritates your eyes, like onion fumes, dust, or allergens, tear production can jump to around 100 times the normal rate to flush the problem away.
Emotional tears are the ones that come with feelings. They can be triggered by sadness and grief, but also by anger, happiness, fear, laughter, frustration, or simply feeling overwhelmed. Music and heartfelt conversations can set them off too.
What's Different Inside
Tears are made of water, salts, proteins, fats, and mucus-like substances that form layers on the eye. They also carry antibodies and an antibacterial enzyme called lysozyme, so they help protect your eyes from germs.
Emotional tears stand out because they contain higher concentrations of stress hormones such as adrenocorticotropic hormone, along with leucine enkephalin, a natural painkiller made by the body. Some researchers think this means emotional tears help balance stress hormone levels.
Even the wiring is different. Reflex tears depend on a particular facial nerve. When that nerve is cut, reflex tears stop, but emotional tears keep coming.
Does a Good Cry Really Help?
Many people say they feel better after crying. Biochemist William Frey of the University of Minnesota proposed that crying helps by flushing out stress hormones. It's an appealing idea, but other researchers point out that tears can only remove a small amount of chemicals, which makes the theory less likely.
Other ideas focus on what crying does socially. One researcher concluded in 2017 that while many animals cry out, only humans shed tears from emotion. He suggested weeping may help others feel empathy toward us. Many animal behavior experts disagree, so the question is far from settled.
If you find yourself crying often or feeling persistently low, it's worth a chat with someone you trust. Talk to your doctor if it doesn't let up.
Why Your Nose Runs When You Cry
Here's a little mystery solved. Tears drain from the inner corner of each eye through tiny openings into a duct that leads straight into your nose. When strong emotion produces a flood of tears, the extra fluid has to go somewhere, so your nose starts running too.
So the next time a movie leaves you reaching for the tissues, you can tell yourself something comforting. Those aren't the same tears you shed over the onions. They're a special kind your body saves for the moments that matter.
