Your bed gathers all sorts of dirt, oil, and sweat while you sleep. Learn how often to wash bedsheets so you can sleep soundly on fresh bedding.

You typically spend upwards of eight hours in bed each day, which leads to the buildup of dirt, body oils, dead skin cells, sweat, and other grime on your sheets and bedding. All this residue isn’t just gross to think about; it can also provide fodder for dust mites, put extra strain on the fabric’s fibers, and trigger health issues including allergies, skin irritation, and acne—not exactly ideal for a peaceful night’s sleep.

The average person changes their sheets about every 24 days, according to a recent survey by Mattress Advisor. But that’s not the best schedule for optimal hygiene and freshness. How often you should wash your sheets depends on a few factors, but there are some general rules that work for most people. Read on to learn exactly how often to wash your sheets, as well as how to preserve their freshness if you decide to bend the rules a bit.

Washing your bed sheets about once a week ensures they stay fresh on a regular basis. Plan to add this task to your weekly cleaning schedule to help reinforce the habit. Keep in mind that you don’t necessarily need to wash sheets the same day as you strip your bed. Having a few different sheet sets on hand makes it easy to quickly swap.

While once a week is a good rule of thumb, how often you should wash your sheets depends on how quickly they get dirty. For example, if you travel often and don’t sleep in your own bed every night, you can probably get away with going a bit longer between washes. On the other hand, if you or your sleeping partner tend to sweat a lot while sleeping, or if you share a bed with your pet, your sheets will become dirtier much faster. Allergy sufferers and individuals with sensitive skin might also want to change their bedsheets more often, such as every three to four days.

If washing your sheets weekly (or more frequently) isn’t feasible, there are a few steps you can take to stretch the time between washes. First, wash your face and bathe or shower before bedtime to reduce the amount of dirt, oil, and sweat you bring into bed with you. Consider having your pet sleep elsewhere to avoid hair and dander on your sheets, and avoid snacking in bed. Owning multiple sets of sheets will also make this chore easier, as you can simply switch out your bedding and leave the laundry for another day.

Now, here are some tips to help you sleep on a clean, safe, and bug-free bed every night:

– Turn back the covers to let the moisture dry for a few minutes before you make the bed

– Wash the sheets once a week with hot water to disinfect them

– Vacuum the mattress a few times a year

– You should wash the bedding more frequently if you are sick, sleep nude, or go to bed without showering after a workout or being outside for a long time

– Wash the pillows at least twice a year, as well as the duvets and other coverings

– Change the sheets often if you sweat a lot during the night, you eat in bed, or if you sleep with your kids or pets

– Apart from the use of hypoallergenic detergent, Joshua Zeichner, MD, the director of cosmetic and clinical research in dermatology at Mount Sinai Hospital in New York City, suggests the use of fragrance-free detergent, but only in the recommended amount, as overdosing “means that the detergent molecules themselves can become lodged between fibers of the fabrics” and lead to irritation reactions.