Microscopic eight-legged mites live in your facial pores and crawl across your skin while you sleep.

Demodex mites are microscopic parasites that have co-evolved with humans for thousands of years. Two specific species, Demodex folliculorum and Demodex brevis, are found exclusively on human skin. Research published in the journal PLOS ONE suggests that nearly 100% of adults over the age of 18 carry these mites, though their density varies between individuals.These creatures are most active at night when they emerge from the pores to find mates and move across the skin's surface at a speed of about 10 millimeters per hour. They are specifically attracted to the sebum produced by sebaceous glands, which serves as their primary food source. Because they are sensitive to light, they remain tucked deep inside follicles during daylight hours.A unique biological trait of Demodex is their lack of an excretory opening. Instead of defecating, they accumulate waste products throughout their 14-day lifespan. When the mite dies, its body liquifies and releases all the stored waste and bacteria onto the skin. While usually commensal, an overgrowth of these mites is linked to skin conditions like rosacea and blepharitis.Scientists use DNA sequencing to study these mites, revealing that different human populations carry distinct mite lineages. This allows researchers to track ancient human migration patterns based on the evolution of the mites living on our faces. Despite their somewhat unsettling nature, they are considered a normal part of the human microbiome.