This post has been quality checked in line with our Editorial and Research Policy.

5 Reasons Why You Shouldn’t Stack Memory Foam Mattresses

If you have two old memory foam mattresses then you might be tempted to put one on top of the other to try and fix the problem of one being uncomfortable.

So can you stack memory foam mattresses and sleep in them?

Stacking two or more memory foam mattresses on top of each other and sleeping in them isn’t recommended because this could cause you back pain, damage the mattress, void the warranty, increase the chance of you overheating, and even trigger allergies.

But if you’ve heard otherwise, then you’ll want to check out the rest of this article because I’m going to explain in detail exactly why stacking memory foam mattresses to make your own makeshift bed is a really bad idea.

And I’ve also provided the answers to some of the most commonly asked related memory foam mattress stacking questions at the end of the post.

Why You Shouldn’t Stack Memory Foam Mattresses

Mattresses stacked on top of each other.
Stacking mattresses changes the structure. Image source: Canva.

The reason why you shouldn’t put memory foam mattresses on top of each other is because the vast majority of memory foam mattresses on the market today have a unilateral design.

This means that the very top of your memory foam mattress consists of a soft layer of ‘comfort foam’ that adapts to your exact body shape to keep you comfortable – before progressively giving way to the harder ‘transition layer’ and a ‘support layer’ that collectively help to support your spine and stop you from sinking too far into the mattress.

The key point here is that the memory foam layers get denser and more firm as you go from the top of the mattress to the bottom.

So when you place two memory foam mattresses on top of each other, the overall structure that you’ll end up sleeping on becomes highly unstable – since the denser base of the first memory foam mattress will crush the softer comfort layers of the second memory foam mattress.

And whilst you may initially feel comfortable, sleeping on memory foam mattresses that have been placed on top of each other night-after-night will almost certainly lead to the following 5 problems over time.

1: Damages the Mattress

Because memory foam mattresses are not designed to be stacked on top of each other, when you do this you’re at serious risk of damaging both mattresses.

For example, the memory foam mattress on the bottom will have its softer comfort layers crushed and the lower support core will be exposed to more weight than it was originally designed to hold.

This destabilises the memory foam mattress that you’re sleeping on which may lead to sagging, indentations, dips, and valleys forming.

And if one of the mattresses is new, then you’re going to significantly decrease its longevity which means that you’ll more than likely have to buy a new one much sooner than if you had not placed it on top of another memory foam mattress.

2: Back Pain

Man sat on a mattress with back pain.
The wrong level of mattress support and firmness can lead to back pain. Image source: Canva.

Nayana Ambardekar – a board-certified general internist and an assistant professor of medicine in the division of general medicine at Emory University [1] – agrees that good posture is important when you sleep, and that your mattress plays a critical role in this [2].

More specifically, if your mattress is too firm or too soft it won’t support your spine properly and could cause discomfort.

Therefore stacking memory foam mattresses can lead to back pain because it changes the stability and the firmness of the surface that you’re sleeping on.

This is an even bigger risk if you’re a front sleeper because even the slightest case of mattress sagging can result in your hips sinking too far into the mattress which puts pressure on your lower back and can lead to pain.

This problem is likely to get worse with time because the integrity of each mattress is likely to decline as described above – leading to greater and greater sinkage and more pressure being placed on your lower back.

And it’s not just your back and spine that’s at risk.

Changes in the firmness of the mattress as a result of material degradation or structural instability can increase pressure points all over your body and lead to muscular discomfort in multiple regions such as your shoulders and neck.

3: Voids the Warranty

Many memory foam mattresses on the market today come with seemingly very generous warranties that may last 5, 10, or even 15 years or more.

But unless you’ve studied many mattress warranties for many different brands (like I have), you may not realise that one of the easiest ways to void your warranty is to place your memory foam mattress on the wrong type of frame.

For example, this can be something as minor as placing your mattress on a base with metal slats – or slats that are too far apart.

So putting your new memory foam mattress on top of another one will almost certainly void the warranty!

4: Overheating

One of the biggest complaints regarding memory foam mattresses is that they retain heat and cause you to feel too hot during the night.

This is because traditional memory foam needs to absorb your body heat in order for it to reconfigure the molecules of the foam so that the mattress can adjust to your exact body shape [3].

Now, most decent memory foam manufacturers combat this by adding cooling gel and perforated or corrugated foam layers to enhance airflow to help keep you cool.

But this structure is totally destroyed when you stack one memory foam mattress on top of another.

Because you’re crushing the aerated structure of the foam layers, and the sheer mass of two memory foam mattresses put together can act as a giant heat magnet that can override the cooling capabilities of the infused gel.

So unless you want to end up a hot and sweaty mess – don’t stack your memory foam mattresses!

5: Triggers Allergies

Woman having an allergic reaction in bed and blowing her nose.
Mold growth in your mattress can lead to allergic reactions. Image source: Canva.

Dr. Gary Zammit, Ph.D, of the Sleep Disorders Institute in New York says that ‘memory foam mattresses are typically a solid block of layered foam’ and that allergy causing dust mites ‘…will live on the surface but they can’t burrow in [to the mattress]’ [4].

And with many brands using hypoallergenic covers on their memory foam mattresses, these types of beds can go some way into helping reducing allergic reactions by inhibiting mold growth and reducing the uptake of allergens like dust mites, pollen, and pet dander.

But this is all ruined when you stack your memory foam mattresses.

Because in addition to trapping heat, the reduced airflow and build up of moisture may result in mold growth.

Which can in turn result in allergic reactions, respiratory infections, asthma, and affect your immune system according to the NHS [5].

So if you’re prone to allergies – stacking your memory foam mattresses isn’t a good move.

Memory Foam Mattress Stacking FAQs

I think that it’s pretty clear that you shouldn’t be stacking your memory foam mattresses based on the reasons I’ve listed above and the sources that I’ve cited.

But what if your situation is a bit different?

Well here are my answers to the most commonly asked questions related to memory foam mattress stacking.

1: Can You Stack Double Sided Memory Foam Mattresses?

No.

Although double sided memory foam mattresses can flipped over individually so that you can choose from two different levels of firmness – you shouldn’t stack them.

Because you’ll still run into the same problems with the warranty, mattress damage, overheating, allergies, and pain.

2: Can You Put a Memory Foam Mattress on Top of a Spring Mattress?

It’s still not a good idea.

Because the springs may dig into the memory foam and destabilise the overall structure that you’re sleeping on which can lead to discomfort and possibly injury – not to mention voiding the warranty.

3: Can You Put a Mattress Topper On a Memory Foam Mattress?

Possibly.

Putting a mattress topper on top of a memory foam mattress may be a good way to alter the firmness and feel of the mattress without going to the expense of buying a new mattress if it isn’t comfortable for you.

However, it’s important to note that the final feel will depend on the combination of your dominant sleeping position, your body weight, if you sleep with a partner, and how the exact specifications of the topper and your memory foam mattress combine.

But I strongly suggest that you do NOT stack several memory foam toppers to make a full mattress because this will almost certainly lack the right amount of support required to keep your hips and spine properly aligned due to the absence of high density support foam.

4: Can You Put a Memory Foam Mattress On the Floor?

It’s not a good idea.

Check out my article called Putting a Memory Foam Mattress On The Floor – 7 Warnings to find out why.

5: What’s the Alternative to Memory Foam Mattress Stacking?

If you’re trying to stack two worn out memory foam mattresses as a way to increase comfort then your best option is to buy a new mattress.

Click the button below to see a list of some of the best mattresses that you can buy online for some high quality selections now.


Sources and References

[1] WebMD – Nayana Ambardekar, MD. Accessed 21/4/20.

[2] WebMD – Best Mattress for Lower Back Pain. Accessed 21/4/20.

[3] Wikipedia – Memory Foam. Accessed 21/4/20.

[4] Fox News – Memory Foam: A Better Night’s Sleep? Accessed 21/4/20.

[5] NHS – Can Damp and Mould Affect my Health? Accessed 21/4/20.

Leave a comment