Emma NextGen Cooling mattress review: A hybrid that won’t leave you hot or bothered

UPDATE: Recently, Expert Reviews has become aware of an increasing number of negative reviews for Emma Sleep on Trustpilot. Emma has assured us that it is working on resolving the issues cited, and has subsequently updated the estimated delivery times on its website and set up a dedicated customer service line. We will be monitoring the situation closely.

Emma’s newest mattress claims to combat the overheating many of us suffer at night, not just in summer. The Emma NextGen Cooling is a bed-in-a-box hybrid mattress that combines layers of foam and tall springs, with a “ThermoSync” layer to help regulate your body temperature while you snooze.

I was already impressed with the breathable properties of Emma’s original NextGen mattress, the Emma NextGen Premium, when I tested it last year and it even came in second in our roundup of the best cooling mattresses you can buy. To find out if the NextGen Cooling would do an even better job, I slept on a double-size sample of the mattress throughout August, with the night temperatures ranging from a brisk 12°C to a balmy 20°C.

The NextGen Cooling did help me sleep and, in tests, I found that it retained less body heat than other mattresses. Admittedly, its price tag is much higher than the NextGen Premium, but I still think this supremely comfortable mattress deserves a Best Buy award.

Emma NextGen Cooling mattress review: What you need to know

You’d be forgiven for experiencing some confusion when trying to buy an Emma NextGen Cooling mattress. Firstly, this mattress doesn’t have its own page on the Emma website. Instead, you have to click the ‘NextGen Cooling’ option on the page for the older Emma Luxe Cooling Mattress.

Delivery was as efficient as with any other bed-in-a-box mattress, which is something worth mentioning given that Emma is still receiving negative reviews for delivery on Trustpilot.

However, I was left wondering whether I’d been sent the right mattress as there’s no product name on the box, in the box, or on the mattress itself, and the Emma NextGen Cooling looks exactly like the Emma NextGen Premium when you first unwrap it. Since both mattresses arrive factory-compressed and folded, and can take days to reach their full height, how would you be able to tell the difference?

Once the NextGen Cooling expanded fully, it was noticeably thicker than the NextGen Premium. At the advertised 27cm (mine was closer to 26cm), it’s 2cm thicker than the Luxe Cooling and 3cm thicker than the NextGen Premium. It’s not as chunky as the 28cm Simba Hybrid Pro, but it’s still deep enough to feel much more durable and luxurious than the NextGen Premium and, unlike the Simba, it shouldn’t give you any trouble with fitted sheets.

Like the NextGen Premium, the NextGen Cooling is built around a layer of “extra-tall” 18.5cm springs arranged in seven “zones” that are designed to provide optimal support for different parts of your body. These sturdy springs make both of Emma’s NextGen mattresses feel more structured and durable than all-foam mattresses, and should help to ensure that your mattress won’t sag or lose firmness over the years.

On top of the springs, the NextGen Cooling has the same three foam layers as the NextGen Premium: a layer of standard polyurethane foam for support, a high-resistance polyurethane foam layer and 20mm of visco-elastic memory foam for comfort. Just below the sleeping surface, there’s an additional 20mm layer of graphite-infused “ThermoSync” foam also found in the Luxe Cooling mattress.

Emma boldly asserts that this ThermoSync foam layer “keeps you cool throughout the night” but I feel that Emma’s wording makes a slight over-promise here. No mattress can actively reduce your temperature – it’s not like putting your sheets in the fridge – instead, a cooling layer like this, or the natural wool layer in the Simba Hybrid Pro, aims to prevent you from overheating. Emma claims the ThermoSync foam achieves this thanks to the infused graphite particles capturing excess body heat.

Like most hybrid mattresses, the NextGen Cooling is designed to be slept on only on one side, so it never needs flipping. Emma says it doesn’t need rotating either but, to help keep your mattress performing at its best for years, you may want to turn it head-to-toe every few months anyway. Fortunately, it’s a relatively lightweight mattress – just 33kg for the king size – and the big side handles help you manoeuvre it.

The sleep side has a removable polyester cover that you can unzip and wash in the machine, up to 40°C. This washable cover also helps to combat allergens, as well as wicking moisture away from your skin to help avoid clamminess and discomfort. The cover feels almost silky to touch but, if you’re like me, you’ll probably want to add a mattress protector to help shield your mattress from moisture and sweat stains.

All Emma mattresses come with a 200-night money-back trial period, plus a ten-year warranty against manufacturing defects.

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Emma NextGen Cooling mattress review: Price and competition

The Emma NextGen Cooling starts at £759 for a single mattress, rising to £1,139 for a double, £1,259 for a king size and £1,419 for a super king. There are also in-between sizes such as the UK small double (£1,049) and the EU queen (£1,379) – while you may not find it as easy to buy fitted sheets and bedsteads in these more obscure sizes, it’s great to have so many options for different-sized rooms.

Although the NextGen Cooling is marginally more expensive than its predecessor, the Luxe Cooling (£1,159 for a king size), the price is comparable with premium cooling mattresses from other brands. For example, the Panda Hybrid Bamboo Pro costs £1,390 in king size, while the Simba Hybrid Pro is £1,329 in king size before discounts.

However, it is significantly more expensive than our top pick for best cooling mattress: the Otty Pure Hybrid Bamboo Mattress, costing just £725 for a king size. Then the Origin Hybrid, which was our choice for best cooling mattress on a budget, is just £629 for a king size. Plus, of course, there’s still the Emma NextGen Premium, which I praised for its ability to regulate temperature and costs just £739 for a king size.

That said, it’s probably worth noting that the NextGen Premium also cost more than £1,200 for a king size when it launched a little over a year ago, and Emma quickly reduced it, even outside their regular discount sales. I feel the NextGen Cooling is perhaps a little too expensive at its current full price, but I’m fairly confident it will become more affordable in the coming months.

Emma NextGen Premium mattress review: Comfort and performance

I loved 2023’s NextGen Premium, which is now significantly cheaper than when it launched, and I’m even more besotted with the Simba Hybrid Pro, which has a special wool layer for temperature regulation. So, when I took delivery of the Emma NextGen Cooling mattress it had a lot to live up to.

I normally sleep on the Simba, but gave it up for August and slept on the Emma NextGen Cooling for several weeks while night-time temperatures rose and fell significantly. A few nights were as cool as 10°C and required a blanket along with my 4.5 tog polyester summer duvet, but other nights saw the mercury hovering as high as 20°C. It was on these warm nights that the NextGen Cooling really proved its worth.

I tend to get hot at night and I share my bed with a husband who gets restless when it’s warm. We generally find that foam and hybrid mattresses are too body-hugging for us, particularly on warm nights, but the NextGen Cooling allowed the air to move and didn’t simply absorb our heat. In fact, the NextGen Cooling seemed to out-perform the Simba Hybrid Pro on temperature regulation.

To put this to the test, I used a heat pad and a thermocouple to measure how much heat the NextGen Cooling retained over 10 minutes while being sat on. After warming with the heat pad, the mattress’s surface temperature fell quickly from 30°C to 22.6°C after four minutes, then more gradually to 22°C after 10 minutes. The ambient room temperature was 20°C, so for the surface to fall all the way to 22°C – while being sat on, remember – is impressive.

In similar tests, the Simba Hybrid Pro remained 4.7°C above the ambient temperature and the NextGen Premium fell to 2.3°C above. This bears out my impression that Emma’s NextGen mattresses are good at staying cool on warm nights.

Emma describes the NextGen Cooling as a medium firm mattress, however, I found it to be noticeably softer than the NextGen Premium, which Emma also describes as medium firm. I have a small frame and sleep on my side so I welcomed that hint of softness the extra layer of foam seems to deliver but my husband, who’s much taller and often sleeps on his back, preferred the firmness of the NextGen Premium.

Again, I ran tests to confirm our impressions: a 7.5kg pile of weights caused the sleeping surface of the double-size NextGen Cooling to sink by 28mm. A similar result to the Simba Hybrid Pro, and more than the 25mm of sinkage I measured with the firmer NextGen Premium while, by contrast, the soft side of the Eve Wunderflip Premium Hybrid sank by a full 36mm.

Thankfully, this softness does not come at the expense of support. The combination of tall springs and multi-layer foam offers a superb level of ergonomic, edge-to-edge push-back. There’s less bounce than I would have expected, even on a slatted base, but the entire sleeping surface feels powerfully supportive in all sleeping positions, without ever feeling hard.

I also found the mattress isolated movement very well, enabling both me and my husband to get a decent night’s sleep, even when one of us was tossing and turning.

Emma NextGen Cooling mattress review: Verdict

The Emma NextGen Cooling combines the best elements of the Emma NextGen Premium and the Luxe Cooling and manages to improve on both.

It’s thicker than its predecessors, with a depth that gives it a sumptuous yet durable feel, and it overcomes a potential problem of the NextGen Premium by adding an element of softness that will make it more comfortable for many side sleepers, without sacrificing support.

Regardless, the headline claim of Emma’s new mattress is in its ability to keep you cool at night and, while no mattress can actively cool you down, the NextGen Cooling certainly earns its place among the best cooling mattresses you can buy. When subjected to tests with a heat pad it cooled down faster than any other mattress I’ve tested, however marginally, and it still excels at edge support and motion control.

The NextGen Cooling is expensive, but so was the NextGen Premium when I first tested it last year, and that has since tumbled in price. I can’t read the minds at Emma, but I predict that the NextGen Cooling will follow suit, becoming cheaper as the months pass. Whether it does or not, this is a five-star mattress – and the free trial gives you 200 days to decide whether you agree.