5 things I wish I'd known before buying a memory foam mattress

The best memory foam mattresses use viscoelastic foam to soften and mould themselves to the contours of your body. That means they provide great pressure relief, and many people find them more comfortable and supportive than traditional sprung mattresses.

But there are a few things people often don't know about this type of mattress that I've picked up over the years. In this article, I'll share my top 5 tips about memory foam mattresses, which will help you find the right one for you and keep it maintained for longer.

Meanwhile, for a full explanation of how memory foam mattresses work, see our guide to what is a memory foam mattress? and our comparison of memory foam vs springs.

1. Not all memory foam mattresses are equal

In general, memory foam has a good reputation. Most people perceive it as a high quality, space age material with special properties that make it more comfortable and supportive than traditional mattress fillings. But until you start shopping for a mattress and trying one out, it doesn't occur to everyone that memory foam isn't one generic thing, but that there are lots of different types. And not all are as comfortable as another.

For that reason, even the cheapest memory foam mattresses tend to include at least a couple of different types of foam. For example, in our Emma mattress review, we note how this 25cm-deep mattress contains three layers of foam: a 3cm breathable Airgocell foam layer, followed by 2cm of visco-elastic memory foam to relieve pressure, and 19cm of supportive cold foam at the base. Much like the special combination of ingredients in a recipe, it's this mix of foams, which unusually includes at least one proprietary type unique to the brand in question, that makes the difference in terms of comfort and support.

At higher price brackets, there are also hybrid mattresses, which mix things up even more by incorporating springs into the memory foam design. For instance, the nicest mattress I've tried this year has been the Silentnight Geltex Pocket 3000 Mattress, which combines an 11cm layer of Geltex (a combination of an extremely elastic gel and air-permeable foam) with two layers featuring 3,000 mini springs, for additional support.

In other words, just because it says 'memory foam' on the description, don't assume it will be the same as another memory foam mattress you've tried. Just as not all down pillows are the same quality (see our pillow filling guide for more on that), all memory foam mattress are certainly not equal, and you really have to do your research to find the right one for you.

2. Bed-in-the-box mattresses have an open-by date

One of the big advantages of memory foam mattress is that they can be compressed and fitted into a box, making delivery cheaper and quicker. Then you just take it out, unroll it, and leave it for a few hours to inflate.

Something I didn't know about these until recently, is that even the best bed-in-the-box mattresses have an open-by date. If you leave them squashed up in the box for longer than that, the foam layers may get damaged and the mattress may take a long time to expand, or not expand properly at all.

I discovered this when I reviewed the Simba Hybrid Essential, because Simba has the good sense to say in their FAQs that it needs to be opened within three months. You can guess why other manufacturers don't, because who in their right minds would buy a mattress and then leave it in a box for so long?

Well, I can think of a few reasons. Your house move might fall through, and it may get stuck in storage behind all your bulky furniture. Or you might, for example, spot a bargain in our cheap mattress deals hub and buy one well in advance of moving house, because the price was too good to wait. If so, be warned!

3. Overheating seems to be in the past

It was once common knowledge that memory foam mattresses would hold onto a lot of heat. That made them good for cold nights, but not so great for hot, sticky ones. Thankfully, however, that seems to be increasingly a thing of the past.

More and more manufacturers are either making their foam more breathable, boosting air circulation and lowering overall temperature, or incorporating special materials such as cooling gels or cooling fibres into their mattresses, to alleviate the problem.

For instance, the Nectar Memory Foam mattress uses a breathable upper foam and temperature-regulating fabric cover to keep your temperature down. Similarly, the Simbatex Foam Mattress boasts a layer of CertiPUR foam, that's infused with heat-absorbing graphite and has open cell structure that circulates 30 times more airflow than other memory foam mattresses.

Meanwhile, even if your memory foam mattress is causing you to overheat, you can alleviate the problem by adding one of the best mattress cooling pads to your bed.

4. They can be tricky to clean

Because memory foam is a petroleum-based material, this kind of mattress needs to be cleaned in a special way, or you risk seriously damaging it. The most important thing is that you mustn't get it wet, which means it should never be soaked in water or any other liquid, and it should also never be steam-cleaned.

As I explain in my article how to clean a memory foam mattress, the first thing you need to do is check the manufacturer's instructions, because each mattress will be different. But in general, the main way you clean a memory foam mattress is by vacuuming it, and if necessary, spot cleaning to reduce stains. Because both of these things are a lot of hassle, prevention is better than cure, so I'd recommend using one of the best mattress protectors to keep it as clean as possible.

5. Trials aren't entirely risk-free

Despite manufacturers' claims, memory foam isn't for everyone. And if you're buying a bed-in-a-box online, you don't even have the chance to try it out like you would in a showroom. For that reason, brands tend to plaster their websites with generous-looking free trial offers, which generally range between 180 and 365 days. That way, you can buy one risk-free, right?

Well, I've learned over the years that trial offers aren't always what you think. For example, with Silentnight's free trial, if you decide you're not happy with your purchase after the first 28 days, and within the first 365, you can exchange it for a different product. However, you can't get a refund, so that does limit you a little. Also, while most companies will pick your mattress up for free, some brands state that you may have to pay for this yourself. In short, it always pays to scour the small print.

And more recently, we've all become aware of another potential danger: that the company will go into administration. That's exactly what's happened to Eve Sleep recently, causing its website to go down entirely. Although it's since been taken over by Bensons for Beds, and the website is back up, the new company will not be honouring any warranties or returns for items purchased on or before 17 October.