Throw Out Your Underwear Every Year
A new study in the UK has revealed that holding onto your underwear for more than a year can become a health risk.
Wearing old underwear can allow bacteria to fester, like E.coli, which can lead to urinary tract and yeast infections.
Good Housekeeping has an article that talks about the risks of keeping underwear too long. Even clean underwear can be filthy, with 83% of "clean" underwear containing about 10,000 living bacteria.
This build up in bacteria is also a reason it's beneficial to sleep without underwear on. The same study also reported some things that should be obvious to most people, like making sure you change your underwear daily. The problem with that is 1 in 4 men wear their underwear for two days before changing them. And something that's super-gross, another study showed that 18% of men and 10.5% of women don't wash their underwear at all. I think those numbers have to be inflated though.
And one more thing you should be changing rather frequently is your bed and pillow sheets. These should be swapped out every couple of years.