In my ongoing quest to get a good night’s sleep, I recently bought a new mattress. The mattress I had been using was a good one, and I had turned it often and flipped it occasionally when I had help. But, I read somewhere that no matter how well you take care of and cover your mattress it will still collect dust mites, and they can cause allergies.

That was enough to send my sleep-deprived self to a mattress store. If my nighttime stuffiness was caused by mites, I wanted them out of my home.

The cheerful salesperson was very helpful and showed me the mattresses that were similar to the one I had bought many years ago. I couldn’t remember exactly when I bought it, but I guessed it was about 2007 so it was probably seventeen years old and almost certainly past its best before date. The salesperson showed me the same brand and quality range in soft, medium, and firm versions and left me alone as I tried each of them out.

Without much delay, I chose the medium firmness, agreed I would also need a new box spring, arranged for delivery, selected a new mattress protector, and paid for my purchases.

This is where it gets funny. When I was trying out the mattresses, it didn’t occur to me to look at their depths. They have changed. Again.

If I hadn’t been so tired, it would have occurred to me that when the salesperson specified a six-inch (instead of a nine-inch) box, he wasn’t making a reference to the fact that I am vertically challenged. At the time, I thought he was, and I told him that I had a husband who was a lot taller than me but that he is now deceased so I don’t need a high bed. He smiled politely but didn’t tell me that the reason I needed a smaller box was not that I no longer had a tall husband but that now I had a taller mattress.

Only when the mattress was delivered did it dawn on me. Ohhhh. Mattresses are now fifteen inches deep! The previous arrangement was for a nine-inch box and a twelve-inch mattress. Now I had a six-inch box and a fifteen-inch mattress and, although they were the same height above the frame as previously, I was going to need new bedding if I wanted to tuck them in.

As I went online to order the necessary sheet set, it occurred to me that the same thing had happened the last time I bought a new mattress. Then, as far as I can recall, the change was from a nine-inch box and a nine-inch mattress to a nine-inch box and a twelve-inch mattress.

So, if my hunch is correct, the people who make mattresses are in league with the people who make sheet sets. They have decided that every fifteen years or so they will change the proportions and force us all to buy new sheets along with our new mattresses.

Mark my words, in a few years, they will change the dimensions again to eight and thirteen, or ten and eleven. They may even integrate the box into the mattress and make us buy sheets with a twenty-one inch drop. And we will, because our mattress overlords will have deemed it so.