Really, truly no mattress heated pad on a foam mattress?

August 10, 2023 6:00 AM

I want to get a heated mattress pad for my bed and my kids' beds. We all have foam mattresses, and after picking a heated mattress pad (on MeFi recs) I see that it says not use on foam mattresses. I assume it's because it will degrade the foam, but how quickly? We'd use it only for an hour at a time, maybe 10 nights a year.

Will it degrade it fast or slow? These are inexpensive mattresses that probably will last five or six years. Is off-gassing, or the heat somehow activating something we don't want to breathe, a concern?

I don't want to do heated blankets, because the kids are chaotic sleepers and a top sheet + blanket twist around them when they sleep and they can't wake up enough to straighten themselves out. Bottom sheet + duvet is the best solution. But it's cold enough here that for maybe 10 nights a year I want to heat up the bed a little before they get in and then turn off the heating pad.

I know that I could 1) replace their beds with innersprings 2) use a hot water bottle or a smaller heating pad. But I want a heated mattress pad for my bed too, because the power pack is on the side rather than at the foot of the bed (our current heated blanket is messy with cords at the end of the bed) and because I don't like a top sheet either.

Do you have any knowledge or expertise in this matter? What happens if I just do the heated mattress pad on the foam mattress despite the warnings?

posted by Ollie to Home & Garden (5 answers total)

Hmm. I was unaware of this warning, and have been using a heated mattress pad on a foam mattress for the past ten years or so. For what it’s worth, I have seen no ill effects.
posted by mbrubeck at 7:06 AM on August 10, 2023 [4 favorites]

Anecdata: my Uncle's foam mattress with electric blanket combo set fire to itself in the 1990s. After many months of use without incident.
posted by BobTheScientist at 8:28 AM on August 10, 2023 [5 favorites]

I used to sell Sealy/Stearns & Foster mattresses. The factory reps advised us against using heated mattress pads or electric blankets in general, but especially on memory foam mattresses. The way the foam works is by responding in changes to temperature; your body heat causes the foam in that area to relax and soften a bit, and that's how memory foam conforms to your shape so well. At the time, the policy was that using a heated mattress pad or electric blanket would likely cause premature failure and collapse of the memory foam, and could void the warranty.

Having said that, the failures that we saw were almost always due to sweat & skin oils, which absolutely will cause the foam to fail prematurely. Even with customers who admitted that they used an electric blanket or pad, we didn't really see overall failures as one would expect with a heated blanket/pad, just a "body impression" marked by sweat stains, where it was clear they were not using a good mattress protector. (Seriously, buy a mattress protector. It's the best single thing you can do to extend the life of your mattress. I told our customers, "Buy it here or buy it online, but please just get one." The customers who faithfully used and cared for their mattress protector, their beds looked great when they were replaced. Those who didn't had a big, stained, body impression in the middle of the bed where the mattress sagged.)
posted by xedrik at 8:58 AM on August 10, 2023 [13 favorites]

The real dangerous gasses from urethane foam are released when it’s on fire, which I imagine is the main concern with a heating pad.
posted by Jon_Evil at 9:02 AM on August 10, 2023 [2 favorites]

A company that sells foam mattresses says, "Tempting as it may be to warm your memory foam mattress as quickly as possible with a hot water bottle or electric blanket/heating pad, we advise you not to do so. Such direct applications of heat can damage the memory foam material and not only compromise its performance but also shorten its overall lifespan."

The Wire Cutter does not seem to be particularly concerned about foam mattress off gassing, and governmental agencies claim that electric blankets are generally safe. So it's more of the question if you will find a memory foam mattress heated with a mattress pad to be comfortable, and if so, if it's worth the decreased mattress life span.

I can imagine that a very judicious use of a heated mattress pad will expose the mattress to less cumulative damage than say a hot running laptop left on the bed for days on end. IME an "inexpensive" foam mattress will be okay until one day it very much it isn't. So if replacing the mattress earlier than its maximum theoretical lifespan will pose a financial hardship, perhaps don't do this.
posted by oceano at 12:50 PM on August 10, 2023 [1 favorite]