We spend about a third of our lives sleeping. That's hundreds of hours spent in our bedrooms. During this time, we shed millions of dead skin cells which, in turn, attract dust mites. If you have pets and let them in your bed, you also let them bring in things like dander, pollen, and even chemicals that could irritate your nose. So, if you're allergic to some or all of the things mentioned above and spend a lot of your time in your bedroom, it's only natural that you experience bedtime or indoor allergies.