After a month of sleeping on the Simba Hybrid Ultra HeatRelease Mattress during some of the hottest nights of the year, the tester reported a happier back, greater comfort in the heat, and no longer dreading getting into bed. The mattress, which costs £2,599 for a king-size, was tested in a bedroom that reached around 30 degrees on the first night.
A Return to Simba After a Regrettable Purchase
The tester had previously owned a Simba mattress and liked it, only switching because of a larger bed frame. After being persuaded by an influencer to buy a different mattress-in-a-box, she spent a year complaining about back pain and a lack of firmness, vowing never to trust a boxed mattress again. Hearing about Simba's latest model, the Hybrid Ultra HeatRelease, gave her reason to reconsider.
The new model includes HeatRelease technology, which Simba says helps sleepers stay up to 4.4 degrees cooler. The technology uses graphite-infused HeatRelease strips to draw excess body heat away, working alongside graphite-infused Simbatex foam and breathable spring construction to transfer heat and encourage airflow. Simba claims the technology begins working within 20 minutes and continues for up to eight hours.
First Impressions and Practical Considerations
At 34cm deep, the Hybrid Ultra is the deepest mattress in Simba's range, a difference that was instantly noticeable. The tester advises measuring your bed frame before buying, as the added height may make the bed sit considerably higher than usual. She also noted that existing fitted sheets may not be deep enough – hers were not.
The depth is not purely aesthetic. The mattress contains 11 layers and up to 7,300 springs, including two layers of Simbatex foam, a PureLift comfort layer, and steel SupportCore springs designed for extra support around the hips and shoulders. As a side sleeper, the tester valued the balance between cushioning and support, finding it firm yet with enough give to feel cradled rather than sunk in.
Cooling Performance in a Heatwave
On the first night, the bedroom was around 30 degrees, putting the mattress to an immediate test. While the tester still felt the heat – it was, after all, a 30-degree bedroom – she was noticeably more comfortable than on previous hot nights that summer. The mattress did not seem to hold onto body heat the way her previous foam mattress had, and she woke up far less bothered by heat beneath her.
Additional features include a Stratos cool-touch cover, a breathable FusionCool comfort layer, and two layers of graphite-infused Simbatex foam, all designed to prevent heat build-up. The high number of Aerocoil springs is intended to reduce partner disturbance, and the top cover zips off for machine washing.
Price, Trial, and Verdict
At £2,599 for a king-size, the mattress is not a budget option. However, it comes with a 200-night trial and a 10-year guarantee. The tester, having previously regretted a mattress purchase, concluded that something you spend roughly a third of your life lying on is worth investing in.
