Eyelash glue is typically applied externally at the natural eyelash base.  Additionally, liquid eyeliners are often used to mask excess glue from the lashes, along with mascara for adding volume.  During the day, these layers will collect grit from the air and collect along the lash line.  By allowing dirt to fester on the eyelashes at night, you are begging for an infection.

There are approximately 50 meibomian oil glands on the upper lid margin, along with the follicles within each of the eyelashes.  Each on of these orifices can become inspissated with oil and become inflamed.  In my general ophthalmology clinic, I often see clogged oil glands presenting as styes, external blepharitis, meibomitis, and cellulitis.  Most times, these infections can be managed using warm compresses and topical medications.  Rarely, the infections can become so severe that inflammation tracks behind the orbital septum–in these cases, both vision and livelihood can be threatened.

False eyelashes during sleep? No way. Vanity should have limits too.