Last Saturday morning I went to a shop to have my car’s oil changed. There was a television on in the waiting area showing Good Morning America. When they broke for a commercial, I saw one for the company Mattress Firm which made the familiar claim that mattresses double in weight every eight years due to accumulated dust, sweat, dead skin, and dust mites.
This seemed ridiculous on its face. The ad made its point like this: a woman was moving house, and as the moving men hefted her mattress she said something like, “I don’t even know how old that mattress is.” The mover said, “I’d say about sixteen years,” and then explained to the woman about the doubling in weight.
A sixteen-year-old mattress is a squicky notion; if I had a mattress that old and a mover who figured it out, I’d buy his silence or flee the country. But I found it more interesting that the mover could so easily handle a mattress that putatively weighed three times what a new, unused mattress would weigh.
But let’s take its premise at face value. Each human sloughs off about eight pounds of dead skin each year. We spend a third of that time in bed, ideally, so we part with two and two-thirds pounds of skin while in bed each year. Let’s round up to three pounds a year. That’s twenty-four pounds in eight years. If you’re lucky enough to share your bed, figure forty-eight pounds in eight years.
Our nightly sweating and other moisture loss is negligible, just a few hundred milliliters at most, and most of that goes into the air, not the mattress, so I won’t count that at all.
According to Ohio State, our mattresses contain anywhere from 100,000 to 10 million dust mites. The best source I’ve found says that 18,875 dust mites weigh about one gram, so they would account for 5.29 to 529 grams in a given mattress. I don’t know how much that varies over time, so I’ll just assume the maximum, which is equal to about one pound.
So the total weight gain for a mattress over eight years is less than 50 pounds. Or would be, except I think everyone peddling these scare stories is leaving out one crucial factor: nobody sleeps on a bare mattress! Most of that sweat, dust, dead skin, mites et al. will go onto our sheets, not our mattresses, and I’d hope those get changed and washed with some regularity. More often than once each eight years, at least.
Certainly some of this dust, skin, and mite material is microscopic enough to make it down through the sheets and mattress covers into the mattress itself, but I have to think that portion of it must be extremely small.
Brand-new mattresses vary greatly in weight, of course, depending on size (twin through California king) and construction. I just did a quick product search at Amazon.com (which is an online source that will include the weight of its products as a matter of course) and found that a new mattress designed for two people weighs anywhere from eighty to maybe a couple hundred pounds. So you’d have to keep your mattress for much, much longer than hygiene would demand, and never change or wash the sheets, for its weight to get anywhere close to doubling.
Have a great holiday weekend, everyone. Travel and eat safely.