​How Long Should You Keep a Pillow?

A few weeks ago, after waking up with neck pain for the third day in a row, I realized it might finally be time for a new pillow. I wasn't happy about it -- I loved my pillow dearly. But it was lumpy, and it leaked feathers every time I leaned against it, and under its case it was the mottled yellow color of a mummy's wrappings. It was also, I realized, approximately 15 years old. This seemed, potentially, very gross.