The truth about that yellow gunk in your eyes—and why it’s actually a sign you’re winning a battle in your sleep.
There’s nothing quite like getting into bed after a long, hard day. You burrow into your pillow, fall asleep, and let your body to replenish overnight. But then morning arrives, and before you’ve even taken your first sip of coffee, you’re staring in the mirror, wondering what that crusty, yellow goop in the corner of your eyes is.
We’ve all done it. That strange, sticky substance that appears unexpectedly as you sleep. Most of us simply brush it away without thinking twice, but here’s the thing: that little collection of crust is far more interesting than you realise.
Thanks to a recent viral TikTok featuring neuroscientist Andrew Huberman, the internet has been buzzing with a shocking revelation: that gunk could be proof that your immune system is fighting (and winning) a microscopic war every night.
“If you’ve ever woken up with that kind of yellowy crust in your eyes,” Huberman told me, “That’s actually dead bacteria that your eyes have successfully defeated during your night’s sleep.”
That’s accurate, those crusty little flecks are like small trophies from a midnight fight your body fought while you were asleep. And when you wipe them away in the morning, you are essentially cleaning up the battlefield.
But what’s actually going on here?
Throughout the day, your eyes are continually protected by blinking, which keeps them moist and removes dust, dirt, and bacteria. When you’re asleep and your eyes are closed, blinking stops. This implies that the tear ducts go into maintenance mode, releasing a slow, consistent combination of mucus, oils, and immune cells to maintain the eye surface healthy and protected.
Because there is no blinking to wash it away, the accumulation accumulates in the corners of your eyes. It can appear in a variety of forms, including crusty, sticky, thick, thin, clear, white, and slightly yellow, depending on the ingredients. It’s very natural and typically nothing to worry about.
This new information was widely shared on social media. One user joked, “I refuse to lose even when I’m sleeping.” Another happily declared, “Starting the day with a victory.” Then there was someone who wrote, “When I was in kindergarten, I put them in my tea,” accompanied by a skull emoji. We are… choosing not to unpack that.
While regular ocular discharge is totally normal, there are a few red flags to look out for.
If you observe a lot of thick, yellow pus around your lashes, especially if it’s accompanied by redness, burning, itching, or gritty irritation, you may have conjunctivitis (also known as pink eye). Bacteria, viruses, or allergies can all cause this disease, which often resolves within a week or two. But it’s really contagious and quite uncomfortable.
To treat mild conjunctivitis at home, the NHS recommends:
Wash your eyelids gently with clean water (first boil it, then cool it, then use cotton pads — one for each eye).
Use a cold, clean flannel as a compress to relieve burning or irritation.
Contact lenses and eye makeup should be avoided until the symptoms resolve up.
Of course, if your symptoms intensify or do not go away, you should contact a doctor.
So, the next time you wake up with a crust in your eyes, don’t be creeped out. Instead, congratulate yourself on the back. Your immune system has been working hard all night, and what about that morning gunk? That is confirmation that you are waking up like a winner.