You may assume falling asleep without washing your face is just a lazy-night ritual but what if skipping that speedy cleanse invited an invisible microscopic to call your skin home? Say hello to Demodex folliculorum, the teeny microscopic mites that live, feed, and even reproduce on your face — most especially at night. While they're a natural part of the skin ecosystem, abandoning skincare can cause these little critters to thrive in some uncomfortable manners.Demodex mites are tiny, eight-legged invertebrates that live on the human face, specifically in and around hair follicles. They are just 0.15 to 0.4 millimeters in size, invisible to the naked eye but numbering dozens or even hundreds at times — as many as five per square centimeter of skin. That may sound creepy, but almost every adult human carries these mites. They exist mainly on sebum (your natural skin oil) and dead skin cells, performing a pretty harmless, even cleaning function in normal circumstances.Consider them micro custodians: they suck up the skin flakes and extra oils that collect during the day. But when their numbers get out of hand, which typically happens due to poor hygiene or compromised immunity, their presence becomes a problem.What Happens While You Sleep 'Mite-fully'?Demodex mites are active at night. They come out of your pores when the sun sets, excelling in the lack of UV light — which is toxic to their DNA. As you sleep, they dine, crawl, and mate on your skin's surface. What's even more interesting (and somewhat alarming) is that they're fueled by melatonin, a hormone your body makes to assist in sleeping.For their services to clean our pores, we unwittingly provide them with melatonin as fuel — a strange, symbiotic relationship that only shows up if something goes amiss.When They 'Mite' Cause Trouble?While harmless in small quantities, Demodex mites can lead to skin problems if they overpopulate — a condition known as demodicosis. In the opinion of Dr. Richard Locksley, a professor of medicine at the University of California, San Francisco, such overpopulation can lead to a variety of skin and eye conditions, including:RosaceaBlepharitis (eyelid inflammation)Acne-like breakoutsItchy, inflamed skinImmunocompromised people are especially vulnerable. When your immune system can't keep mite numbers in check, allergy and infection can follow. Ironically, your own sleeping habits — or lack thereof — can determine their level of activity. Lack of sleep boosts oil secretion, which provides mites with even more to munch on.How Skipping Face Washing Adds To the Mite Population?Letting makeup, grime, sunscreen, and impurities sit on your skin overnight can provide an all-you-can-eat buffet for Demodex mites. Left behind, these layers seal excess oil and dead skin cells — prime breeding ground for mites.This is particularly troublesome in the area around the eyes. Eyelash follicles tend to be a breeding ground for mite overgrowth, particularly when mascara, eyeliner, or false lashes are not removed effectively. This results in irritation, plugged glands, and increased susceptibility to such conditions as blepharitis.One of the most fascinating findings appears in a 2022 paper in Molecular Biology and Evolution, which indicates Demodex mites are becoming permanent residents of the human body — literally. Scientists discovered that the mites are losing unnecessary genes as a result of their snug, predator-free existence on human faces.Actually, their body structures are so sparse that single-cell muscles control each of their legs. They also have a reverse process of maturation — losing cells as they mature rather than adding them. Since such close biological incorporation, scientists believe that one day they will be able to integrate genetically with human hosts. It may sound like science fiction, but it's a possibility biologically.Should You Be Worried?For healthy individuals, there's no reason to panic. Demodex mites are not dangerous per se. In fact, they're so widespread they're actually thought of as part of the skin microbiome. But they can become an issue when individual hygiene is lax — especially before bedtime. Here's what you can do:Always wash your face at night. Use a light, non-comedogenic cleanser that strips away oil and debris.Remove eye makeup and false lashes. These are usual sites mites over-colonize.Don't neglect your sleep. Lack of sleep heightens sebum production, inviting mites to flourish.Consult a dermatologist if you have persistent redness, itchiness, and inflammation in the skin.Your evening skincare routine isn't vanity, it's a defense system against an unseen, millennia-old species that lives on your face. Though Demodex mites are generally harmless housemates, bad hygiene and broken sleep habits can cause them to become freeloaders with no plans to leave.