Why Do Tears Come Out When I Cry?

Two adult hosts. Lightly edited for reading; small differences from the audio are possible.

Host 2: Hello, welcome to the podcast. Dad, how does it work? Imagine you're sitting on the couch watching a movie, and the main character finally, you know, after this huge adventure, finds their lost dog.

Host 1: Oh, that's the best part, right?

Host 2: You feel incredibly happy. But then suddenly your eyes just fill up with water.

Host 1: Yeah, completely out of nowhere.

Host 2: Exactly. I mean, a minute earlier everything was totally fine. So why does the human body just suddenly decide to leak, you know, just because we feel a strong emotion?

Host 1: Well, and it's not just happiness, right? The exact same thing happens when we experience, like, sadness or anger or even just frustration.

Host 2: Yeah, definitely. Which is why our mission for today's deep dive is to sort of map out this hidden plumbing system of the human eye and figure out exactly how your brain hijacks that system when you feel something so intensely.

Host 1: That's a great way to put it. But, you know, to understand the overflow, we actually have to start with a completely ordinary, boring day.

Host 2: Okay. Lay it on me.

Host 1: So your eye is basically a small biological window. And just like a real window, it needs a constant gentle rinse to stay clear and comfortable.

Host 2: Right.

Host 1: So even when you aren't crying, there's this microscopic wet layer covering each eye.

Host 2: Wait, really? But I don't feel water, like, sloshing around in there.

Host 1: Right. Because it's so thin. But if it's constantly being rinsed, there has to be a continuous flow of fluid, right?

Host 2: So it's basically a tiny sink?

Host 1: And if it's a sink, it needs a faucet and a drain.

Host 2: Okay, well, I've always noticed tears pooling near the inner corner, like right by the nose. Is that the faucet?

Host 1: Actually, it's the exact opposite.

Host 2: Oh, really?

Host 1: Yeah. That inner corner is the drain. The faucet, or the tear gland, is tucked right up under the bone on the upper outer side of your eye.

Host 2: Oh, wow. So the supply is top outside and the drain is bottom inside.

Host 1: You got it.

Host 2: That makes perfect biomechanical sense. I mean, when you blink, your eyelid must act like a windshield wiper.

Host 1: Yeah, sweeping the fluid diagonally.

Host 2: Right, from the upper corner down to that inner corner drain.

Host 1: Spot on. Blinking spreads that protective layer evenly. And once the fluid reaches those tiny openings by the inner corner, it drains down a little passage right into your nasal cavity.

Host 2: So it's basically a tiny sink.

Host 1: Exactly. And if it's a sink, it needs a faucet and a drain.

Host 2: So you constantly have this microscopic amount of tears keeping things balanced.

Host 1: Exactly.

Host 2: Okay. Plumbing mapped: supply, sweep, drain. But let's go back to the movie.

Host 1: Right, the lost dog.

Host 2: Yeah, the dog comes running over the hill. Your eyes don't suddenly get dirtier, right? So they don't need a bigger wash. What triggers the flood?

Host 1: Well, your brain does.

Host 2: My brain?

Host 1: Yeah. When you experience a really strong feeling, your brain recognizes that intensity and it fires off an automatic signal to those tear glands.

Host 2: Oh wow.

Host 1: It essentially commands the glands to just flood the system.

Host 2: Wait, so the brain just, like, hits an overdrive button because it's overwhelmed by the emotion?

Host 1: That's exactly it. It's a completely automatic response to that intensity.

Host 2: But wait, why do we get a runny nose? If the drain is in the inner corner... oh, I see, the tiny sink gets backed up.

Host 1: Bingo. The drain is built for a gentle, everyday trickle.

Host 2: Right. Not a flood.

Host 1: Exactly. When the brain demands a sudden flood, those tiny openings simply cannot carry that massive new volume all at once.

Host 2: So the sink overflows. The extra fluid pools up, you know, breaches the eyelids and then gravity just pulls it down your cheeks.

Host 1: And the drain is still working as fast as it can.

Host 2: So it's dumping a huge amount of that liquid down the pipe straight into your nose. Bam. You've got the sniffles.

Host 1: That's the cause and effect right there. I mean, a tear on your cheek is really just eye fluid escaping an overwhelmed system.

Host 2: Okay. That brings up a weird scenario.

Host 1: Oh, what's that?

Host 2: Well, if I'm helping chop an onion for dinner, my eyes start watering like crazy, my nose runs, the exact same overflow happens. Did the onion secretly hurt my feelings?

Host 1: No, no emotional crisis there.

Host 2: Good to know.

Host 1: Yeah, onions release a chemical that physically stings the surface of the eye.

Host 2: Oh, okay.

Host 1: So your brain detects that irritation and cranks up the water supply to flush it out.

Host 2: So it's the identical overflow mechanism. It's just triggered by a physical alarm instead of an emotional one.

Host 1: Precisely. Which, you know, highlights something really important about emotional reality.

Host 2: What's that?

Host 1: Crying isn't, like, sadness leaving the body, and tears definitely aren't a scoreboard that measures how much someone cares.

Host 2: Meaning, like, if a friend isn't crying at the end of the dog movie, it doesn't mean they're heartless or they don't feel anything.

Host 1: Right, exactly.

Host 2: Their brain just might not trigger that specific physical flood response to an intense feeling. I mean, everyone's biomechanics react differently.

Host 1: Exactly right.

Host 2: So doing a quick recap of the deep dive here, the upper outer glands supply the fluid, blinking sweeps it across the window of your eye, and those tiny openings by the nose act as the drain.

Host 1: Perfect summary.

Host 2: Thanks. But when you get hit with a huge feeling, or, you know, a stinging onion, the brain hits overdrive. It makes way more water than the drain can handle causing it to spill onto our cheeks and run into our nose.

Host 1: Yep, the plumbing is simple, but the brain's connection to it is incredibly complex.

Host 2: I bet.

Host 1: In fact, experts are still studying the exact evolutionary reason why humans cry from emotion.

Host 2: Wow. And that leaves you with something fascinating to think about. Next time you feel a tear escape, consider that maybe those tears act as a silent signal.

Host 1: Oh, I like that.

Host 2: Without you having to speak, that overflow shows the people around you that something deeply matters. Or, you know, that you might need some comfort.

Host 1: Right. A silent alarm for empathy.

Host 2: If this sparked your curiosity and you want to hear more episodes like this, make sure to follow our podcast to catch new episodes and updates.