As I researched some more, there is nothing that says you must wash your sheets every X days but here are some pretty gnarly facts by Philip Tierno, Professor of Microbiology at New York University School of Medicine that will encourage you to wash your sheets sooner than later -
Every night we shed one and a half million clusters of skin per hour. Multiply that by 7 or 8 hours and you wake up in 12 million particles of dead skin. These discarded skin particles make for a delicious meal for dust mites that leave behind feces and when they die, leave their bodies too. After five years dust mites make up 10% of your pillow. Isn't that inviting to think you are laying amongst harmful bacteria AND bed bugs crawling on your body???? I think I might just sleep standing up now.
In addition, beds are full of bodily fluids; sweat, oil, saliva, snot, etc, that seep into the sheets. After 10 years of dead dust mites and bodily discharge, your mattress will double in weight from all the debris. Yum.
I grew up in a household where our sheets got washed every week. Praise the Lord for moms! I can honestly say that when I went off to college, this wasn't the norm. I hated, and still do, changing the sheets. It's a process and to this day I despise washing the sheets. It's not so much the washing, it's the making the bed part. But I have to look at it this way...if I only washed my sheets once per month, that would be 8 hours per night for 30 days totalling 240 hours in the sheets. That's like wearing the same clothes for 10 days straight without taking them off or washing them. I would NEVER do that!
Here's what I propose - pick a day every week that works for your life & routine and wash your sheets on that day. Yes, every seven days. Make sure you set your cycle to super HOT and dry them in a HOT dryer to ensure that you're killing any living creatures lurking.
Now sleep tight and don't let the bed bugs bite!!