Sleep, eye crusties, eye boogers, eye dust, eye gunk, the stuff in the corner of your eyes when you wake up, also known as eye schnooters... What is that?

Eye crusties are a mixture of protein, oils, dead skin cells, and even bacteria.

Chemically speaking, it's a three-layer complex mixture of stuff.

The innermost layer is made of proteins called mucins, which have a coat of sugars that helps them trap water and form a nice protective layer of gooey mucus.

The next layer is actually... your tears, which contain a variety of substances, but really they're mostly salt water.

And the outermost layer is a complex oily mixture called meibum, which helps seal that moisture in and protect your eyes from drying out.

It's made of a bunch of things, just a few of which you're seeing here.

This three-layer film of protein, water, and oily stuff helps protect your eyes from the elements and keeps you seein' good.

Normally, during the day, you blink excess eye stuff out of the way.

But at night, you're obviously...not blinking.

So it builds up and dries out instead, and collects at the corners.

Some of the fats in meibum melt just under daytime human body temperature.

When we sleep, our body temperature can drop a little below this melting point, encouraging those fats to solidify a little more, which enhances that eye crusty crustiness.

How crusty or soft your eye gunk is depends on how dry your eyes are.

The drier your eyes, the crustier the crusties.

Most of the time, eye crusties are nothing to worry about.

But excess gunk can be a symptom of eye disease, like conjunctivitis.

For most of us, most of the time, it's just part of waking up.