Follow CBSMIAMI.COM: Facebook | Twitter

MIAMI (CBSMiami) — How often do you change your bed sheets? Once a month? Twice a month?

A new survey by a bedding review site found most people are not changing their sheets often enough. The average person goes about 24 days, or more than three weeks before changing their sheets. The average is even longer for pillowcases.

What’s more, the average number of days that people can go without changing their sheets before they consider it “gross” is just over 35 days.

Experts say sheets should be changed once a week to once every two weeks at the most.

Sweat, dust mites and other microscopic life in between our sheets left to long can make us sick.

Humans produce 26 gallons of sweat in bed every year, according to Business Insider. That makes it a perfect spot for bacteria. Other things that can add to the mess are animal dander, pollen and soil. It only takes about a week for all of that buildup to get out of hand.

Experts say sheets should be run through a hot cycle, around 130 to 150 degrees Fahrenheit, to kill all of the germs.