There are some questions about the human body that, once they come to mind, you just can't rest until they're answered. Since we've already tackled the question of why your period makes you have to poop more, it's time to talk about eye boogers: What are they and why do they happen to good people?
As the video above from SciShow explains, scientists don't actually have an official term for eye boogers. They can be referred to as "gound" or "rheum"; these terms generally refer to any discharge that comes from mucus-producing areas like your eyes, nose, or mouth. Eye boogers, a.k.a. "sleepies" or "the sleep in your eyes," are essentially a cocktail of this mucus, plus bacteria, dust, lint, and dead skin cells.
You may not love the idea of all that crap collecting in the corner of your eye — and it's actually getting in your eyes all day long. When you're awake, you blink a lot, so it's constantly being flushed out, leaving behind only the mucus that keeps your eyes moist.
When you sleep, however, you're not blinking, and that's when buildup occurs. The consistency (crusty versus sticky) of your gound can vary with allergies or how much you touch your eyes throughout the day.
The important thing to remember is that, as icky as they may be, eye boogers happen to everyone. More often than not, they're totally harmless — it's only when you notice an excess (they're bad enough that you have trouble opening your eyes in the morning, for example) that you should check with your doctor. That can signal an infection, like pink eye, or another eye condition.