Verify: Do mattresses double in weight from dead skin and dust mites?
When was the last time you got a new mattress? Mattress ads try hard to gross you out, so you’ll buy a new one every 8-years.
This is a TV commercial from Sit ‘n Sleep, a chain in California.
"After 8 years you mattress practically doubles in weight from sweat, dead skin and millions of dust mites,” said owner Larry Miller.
That got Verify Viewer Darrin Carpenter wondering this: “Do mattresses actually double in weight every eight years?”
Sweat, dead skin and dust mites? Does a mattress really double in weight?
To verify this, first thing I need is an old mattress. I asked Verify viewers if they had one I could use for this story and that’s how I found one that’s 20-years old to put through some testing.
But first, talk dead skin.
Working from a 2011 study from the Journal of Environmental Science and Technology, two people would shed about 9 combined pounds of skin, during 8 years of sleep. And that's assuming they're sleeping right on a mattress, without sheets, like barbarians. So, that’s not much weight.
Ok, back to the mattress.
Chad Lytle has a Ph.D in molecular biology. He works at Research Associates Laboratory in Allen, Texas. They're going to DNA test this thing.
To see what's living on this mattress, we're swabbing. Taking samples from the surface.
And to see what’s on the inside we used a chainsaw to cut it open.
Remember, the ad said weight comes from sweat. And it looks like a pattern of brown rust stain, where the pad hits the springs. But, it’s dry inside. So water's not accumulating.
How about DNA?
“We're going to be able to see some things you can't see with the naked eye. We're going to be able to see what's been there. What's walked there,” Lytle tells me.
“You're telling me that this test, if there ever was one mite on that mattress and walked across that area, you'd be able to know it was there?” I ask.
“At least a reasonable time period of a couple of months or so, yeah,” he answers.
While we wait for the results, I'm meeting with Dr. Mike Merchant from Texas A&M University. He's an urban entomologist, an expert on city bugs. I'm learning dust mites are invisible to the naked eye and their favorite food is dead human skin.
“Dust mites get benefit from living with people. We provide them with a nice stable environment and food. We don't get anything back,” Merchant said.
“Ah, they're freeloading,” I said.
“They're freeloaders on our homes,” Merchant answers.
A study from Ohio State University looked at the mattresses of 150 schoolchildren in Norway. In foam mattress, with mattress covers, researchers found evidence of mites 26% of the time. Without mattress covers -- 40% of the time.
“Could there literally be millions of dust mites in your mattress?” I ask Merchant.
“A million dust mites could probably fit in a thimble head. It's a tiny, tiny amount spread out over a large area,” he answered.
So, mites are there, but Merchant doubts they're adding any real weight.
Ok, back to the lab where Lytle found dust mites on the mattress.
“Absolutely positive,” Lytle said.
“Positive. How positive?” I asked.
“Very positive,” he responded.
So, this thing has mites. No surprise. But is it full of them? Like, enough to weigh it down?
“How do you compare the number of mites you found on the surface of the mattress to the number of mites on the inside?” I ask Lytle.
“Probably 100-fold more on the outside then there is on the inside,” he said.
“Is it possible to have double the mattress weight just in mites?” I ask.
“I don't think so. You'd have to have an awful lot of mites. Talking billions. We sure didn't see when we opened,” Lytle said.
Okay, there's not much weight coming from mites or sweat, or dead skin. The only question left is, has this old mattress doubled in weight?
The manufacturer told me they don't have a record of what it weighed when it was new.
So, I looked up the weights of 50 California Kings sold at Home Depot. The average weight is 98.4. Before we cut it up, we weighed ours it came back at 102.1 pounds.
So, do mattresses double in weight after 8-years, like the say in the ads? The answer... is... no.
I checked back in with Larry Miller, who produced the ad for Sit ‘n Sleep. He provided a few web articles that he says prove that mattresses double in weight. Both reference the source as Dr. Philip M. Tierno, Clinical Professor of Microbiology and Pathology at NYU.
So, I contacted Tierno who sent me this message, saying the claim is false.
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