After a long day of school, sports practice, and mountains of homework, most students view their beds as sources of  welcome relief from the stress of daily activity. Lying beneath the covers feels like an oasis, where nothing in the outside world can harm you.

What can harm you, however, are the tens of thousands of tiny, microscopic insects living deep within the micro-fibers of your sheets, pillowcases, and comforters. For this very reason, the healthy habit of the issue is to change your bed sheets and pillow case at least once a week.

The most common form of insect found in your bed is the dust mite, which causes many people with allergies to experience wheezing and puffy eyes during sleep. While you sleep, your body gives off dead skin cells, much like a snake would. These dead cells are what attract mites and creepy-crawlers to want to join in.

Another unwanted intruder is the bed bug. Before a feeding, this insect is incredibly small and flat, about the width of a piece of paper. They hide in the crevices of sheets and then feed on the blood of a sleeper during the night. Depending on your individual reaction to the bug’s bite, you may not even realize that you have bed bugs. The best way to avoid them, in addition to frequently changing the sheets, is to make sure none of your bed linen is touching the floor and to place a zip up mattress cover around your mattress.

Pillowcases are often overlooked in discussions about hygiene, but are one of the most important elements in maintaining a clean sleeping environment. Because the natural oils from the skin rub off during sleep, if a pillowcase is not frequently changed it can lead to clogged pores and acne.

For those of you who cannot remember the last time your bed had fresh linens, go home, change your sheets, and get the peace of mind that comes from knowing no unwanted guests are sharing your bed with you.