The monsters in your nightmares are living and pooping and dying inside your pillow.

Dust mites — lumpy, hairy, fat-bodied, microscopic atrocities — are way worse than you have probably ever cared to think about. And they MITE be (probably are) making you sick.

These teeny-tiny bugs feast on your dead hair and skin, and according to research, after two years of use, one-third of your pillow’s weight is made up of the species, their droppings and their carcasses.

So if you have three pillows under your bed, and have slept on them for more than two years, congratulations — you’re sleeping on a whole pillow’s worth of bugs and feces every night.

If you have allergies, your pillow hotel for mites is making them worse. If you suffer from asthma, same thing. If you have neither, it’s just a matter of time before the mites irritate your sinuses and make life worse than it already is. The same study showed that 10 percent of people, and 80 percent of allergy sufferers, are allergic to the critters’ waste and their decomposed bodies.

What can you do? Wash your pillows every six months, wash your pillowcases every week and maybe destroy all your skin and hair, because as long as you have both, the dust mites will always return.