By Ann Wang (‘26)
In the final week of school, everything feels heightened: stress from exams, the surreal goodbyes to graduating friends, and the quiet domineering pressure of Grade 12 creeping closer. I’ve cried more times than I want to admit, in hallways, bathrooms, and even in silent classrooms. Sometimes it was from stress, other times from laughter that turned bittersweet, or a hug I didn’t want to pull away from. But every time, the tears felt different. And as it turns out, they are…
Our tears aren’t all the same; they have chemistry as complex as the feelings that trigger them. And like the chemistry nerd I am, of course I had to write an article exploring the ✨chemistry of tears✨
Three Types of Tears
First off, humans produce three kinds of tears in general, each with its own purpose and composition:
1. Basal Tears
Technically, we’re crying all the time because basal tears are always present in our eyes, forming at 2μL per minute to keep our eyes moist, nourished, and free from dust or microbes. Basal tears contain the highest protein and lipid content out of all three types of teardrops. Specifically, they contain lysozyme and lactoferrin as well as the electrolytes sodium and potassium. Out of the three types of tears, the quantity of lipids and protein secreted is the highest in basal tears
2. Reflex Tears
Reflex tears are your eyes’ emergency response team. Whenever something irritates the eye, such as dust, smoke, or even the sting of chopping onions, these tears flood in to flush the intruder out.
It starts with TRP channels (short for Transient Receptor Potential channels), which are sensitive protein gateways in your nerves. When these channels, especially in the ophthalmic branch of the trigeminal nerve, detect something irritating, they send a signal to the brain. That signal then activates the lacrimal glands to release a surge of reflexive tears.
Interestingly, this reflex system was first observed in the fruit fly, Drosophila, where researchers began mapping out the different types of TRP channels. Since then, scientists have identified over 30 different subtypes, all capable of detecting changes like heat, pressure, and chemical irritants. These channels allow ions like sodium, calcium, and magnesium to flow, kickstarting the body’s rapid response.
Although reflex tears are similar in composition to basal tears, they have more of a specific protein called tear lipocalin. This protein is produced by specialized acinar cells in the main lacrimal gland and makes up about 25% of the protein content in reflex tears. Tear lipocalin has a special job: it helps bind and transport small molecules, including harmful ones, out of the eye.
In short, reflex tears are a chemically equipped, fast-acting defense system designed to protect your vision from the attackers of the outside world.
3. Emotional Tears
Unlike basal tears, which are always present to lubricate the eye, or reflex tears, which wash away irritants like dust or onion fumes, emotional tears are rich in chemical signals of stress and emotion. Interestingly, any tears attributed to strong emotions (happy, sad, angry, etc.,) all share a similar composition (as far as I am aware in my brief research).
In general, they carry adrenocorticotropic hormone (ACTH), which is linked to the body’s stress response, and prolactin, a hormone tied to emotional regulation. These tears also contain neurotransmitters like acetylcholine, which plays a role in calming the body, and adrenaline and noradrenaline, which are part of your “fight or flight” response. When you’re sad, scared, grieving, or even overjoyed, these chemicals flood your system. Crying becomes a physical release and a way for the body to literally shed those overwhelming emotions.
Moreover, scientists have also identified leu-enkephalin, an endorphin-like neuropeptide in emotional tears. This compound helps to dull pain — both physical and emotional — and might explain why crying can lead to a sense of relief or catharsis afterward. That post-cry calm isn’t just in your head: it’s in your bloodstream too!
For centuries, emotional tears were thought to serve no real biological purpose; even Charles Darwin dismissed them as useless. But modern science tells a different story: they serve both a biochemical function and a social one, allowing us to connect, communicate, and process the invisible. That’s why, when words fail in goodbye hugs and friends you’re not sure you’ll see again next year, tears speak. They’re a natural blend of biology, chemistry and emotion: a kind of alchemy we all share that helps us heal and hope.
References:
All about emotional tears. (2017, February 28). American Academy of Ophthalmology. https://www.aao.org/eye-health/tips-prevention/all-about-emotional-tears
News-Medical. (2023, October 2). What are Tears Made of? The Biochemistry of Emotion. https://www.news-medical.net/health/What-are-Tears-Made-of-The-Biochemistry-of-Emotion.aspx