Do Memory Foam Mattresses Sag?

If you’re considering the idea of investing in a memory foam mattress after seeing and ready all the hype surrounding them, you may be wondering will it start to sag because it doesn’t have springs?

Memory foam mattresses are specifically designed not to sag. Their unique internal structure self expands when the weight is taken off the mattress. Yes a very cheap memory foam mattress is likely to have a more basic structure and is likely to sag after a number of years. This is only natural, just as a chair pad or cushion pad would start to show signs of wear and tear after a few years. A more advanced memory foam mattress however, put through a rigorous testing programme and developed scientifically is much less likely to sag over the course of its life and will more than likely last around 8 – 10 years before it shows signs of any sagging.

Tempur Malmo Mattress Honest Review 3

Why would a memory foam mattress sag?

The design of a memory foam mattress is to mould and adapt to the contours of your body – providing more support and pressure relief than a regular sprung mattress.

Memory foam mattresses are made up of either tiny particles of memory foam, sheets of memory foam with pockets and some even have a special type of gel built into the memory foam.

As a result of long periods of compression, when you lie in bed at night, the memory foam gets squashed and held that way for a long time.

Just like in any other object that is designed to take weight, a sofa, a computer chair, a sun lounger pad, a memory foam mattress can eventually get worn out from all the compressing a decompressing and start to sag in the areas where the most weight is applied.

Which type of memory foam mattresses will sag?

Generally speaking, if you have a more advanced memory foam mattress such as a Tempur mattress or a Simba mattress – you will not experience sagging.

(Unless there are any exceptional circumstances.)

When you cut costs and get a cheaper memory foam mattress or even a topper, they are generally made from a much cheaper foam material with less complex internal structures.

(Meaning you are much more likely to encounter a sagging mattress after a few years – or even after a few uses.)

Now don’t be put off by this. Don’t forget that the memory foam mattresses I am referring to here are the very cheap ones that are usually unbranded – they are quite often available on Amazon and are for very occasional use and for spare bedrooms only really.

How long will it take for a memory foam mattress to start sagging?

If you have a decent memory foam mattress from a reputable company or manufacturer, you shouldn’t expect to see any sag in the mattress for a good number of years.

If you buy a very cheap bargain mattress from Amazon that is made of a low quality foam, it is possible that is could start to sag after just a few uses.

The price difference between a mattress that is likely to sag after just a few uses or weeks is £1000’s of pounds.

(We are talking a £40 mattress compared to a £2000 mattress.)

So don’t freak out. – Your Leesa mattress shouldn’t start to dip any time soon!

Is it the bed or the mattress that is causing the sag?

Most often it is the mattress itself that is starting to sag.

Whether from a lot of pressure being applied in one spot, causing the foam particles to move. Or from general use, every night for 8 hours or so.

Sometimes though, it can be the bed frame or base itself which is causing the memory foam mattress to sag.

It may be that you have a fairly basic or thin frame base underneath the heavy memory foam mattress and quite simply, the weight of you, plus the mattress has started to warp or bend the pice of board that supports the bed underneath.
Find out if this is what is causing your memory foam mattress to sag by lifting the mattress off the base and inspecting the condition of the base underneath.

Another reason for a memory foam mattress starting to sag is because you have it positioned on a slatted bed frame / base.

From experience, a slatted base does not seem to be the best possible base or support for a memory foam mattress – unless the mattress has some extra support built in (like springs for example.)

Have a check underneath your mattress to see if any slats have either become dislodged from their slots or have even snapped!

(This is going to create a hole in the supporting frame and will most certainly cause your memory foam mattress to sag.)

How can I prevent my memory foam mattress from sagging?

All you can really do to stop your memory foam mattress from sagging is to take good care of it – avoid doing silly things like standing on it obviously!

Many memory foam mattresses do not require being turned over like tradition sprung mattresses. –

The internal structure of the different layers means that the softer more squishy layers are on top of the mattress for ultimate comfort and the stronger more supportive layers are underneath for support and to give the mattress body.

All you can do is rotate the mattress without flipping – this can be done every couple of months to allow the main areas of weight from your body to press on different areas of the mattress.
This prolongs the life of the mattress and will definitely help to prevent sagging.

Some memory foam mattresses have a removable topper. Unzip this and see if it is indeed the mattress sagging or just the topper.

You could rectify the problem by aerating and shaking the mattress topper to resettle the memory foam fibres, filling any patches that may have developed.

Which type of mattress will sag more, a memory foam or a sprung mattress?

Many people would think that a memory foam mattress would sag more or more quickly than a traditional sprung mattress.
However, this is not necessarily correct.

A sprung mattress, whether spring or pocket sprung mattress can easily start to sag. – From experience of owning a sprung mattress before switching to a memory foam Tempur mattress, I found that no matter which way we flipped or spun the sprung mattress around, after a few years (approx 4) it had absolutely had its day and would not give an even level of support.

Whilst the mattress did not appear to sag visually on the surface. When lying on the mattress is became apparent that areas had sagged and were like little areas which were not as supportive as the rest of the mattress.

This was a cheap sprung mattress to be fair – so this is likely the reason for it starting to sag. – Perhaps a more expensive and better made spring mattress would not have given us these problems.

In comparison to this, a cheaper more basic memory foam mattress is likely to sag quite quickly, – some cheap mattresses for sale on Amazon actually show signs of the support failing after just a dozen uses.

(But you have to remember that these cheaper mattresses are not built to withstand constant use and designed to be for occasional use.)

If you choose a well known brand of memory foam mattress, you will be able to trust in them that the mattress will not start to sag – at least until the manufacturer advices the life expectancy of the mattress – be it 8 or 10 years.

Advanced memory foam mattress are put to rigorous testing.

Read our detailed guide on the best memory foam mattresses you can buy here.

(A bit like a fabric rub test, but for the weight and force of a human body lying on the mattress every night for years and years.)

So you can trust when they say that these memory foam mattresses are built to last and withstand being used for years without sagging.

One final thing to consider:

When wondering if your memory foam mattress is going to start sagging, check the weight recommendation from the manufacturer.

For example:

The Leesa mattress has a 300lbs per person weigh limit – so 600lbs in total. (This is 21 stone each person.)

However, what they also state is that for the mattress to last as long as possible without sagging, a more ideal max weight would be 200lbs or 14.3 stone per person.

In terms of a really bad, sagging mattress with a huge indent in the middle – I have been fortunate enough to never have had a mattress that looks like this. I think the only explanation for mattresses like this is years and years (like 30 years of solid wear and tear). At this point, for your own health and sanity – you are best prioritising the purchase of a new mattress.