I Slept on the Simba Natural Hybrid Source Mattress for a Month: Here’s My Honest Review

Simba gifted me this mattress and bed frame for review. Every opinion below is my own, including the parts Simba may not love, but that’s why I keep my reviews honest for my readers so that you know they are trustworthy.

I’ll be upfront from the start: this is a beautifully made mattress, it kept me cooler than any bed I’ve slept on, and on its own without a mattress topper, it was too firm for me as a lover of soft beds.

When Simba offered to send me their Natural Hybrid Source to review, I was curious for two reasons. It’s a sprung mattress filled with British wool rather than foam, which is rare for a “bed in a box” brand. And Simba is a certified B Corp, so I wanted to see whether the sustainability story held up when I looked closely.

A little context on how I sleep, because it matters for everything that follows and how you compare your own mattress needs against mine. I always fall asleep on my side, roll onto my back during the night and wake up on my back. I’m used to a very soft bed, I’m a hot and light sleeper, and I share the bed with my partner, whose movements usually wake me up.

I’ve now slept on the Source every night for over a month. Here’s what I found, including why I added a topper after the first week but why I still love it.

Simba Natural Hybrid Source at a glance

Delivery and set-up

I had Simba’s VIP delivery service, and it made the whole thing effortless. Two men carried in the bed frame and mattress, unboxed everything and set up the bed for me, so I didn’t have to do a thing. The bed frame arrived already assembled in 3 parts, and the mattress is heavy, so I was very glad to not be wrestling it through the front door myself. 

I would definitely recommend the VIP service, especially if you will be at home by yourself on the day of delivery, as the two man delivery had it set up and ready to use in 15 mins. This made it so easy for me to continue going about my working day, as we all know how stressful it can be moving house or figuring out how to assemble new furniture. 

The mattress came delivered flat, it was not wrapped up in a box, it was covered with protective plastic packaging and with cardboard corners to protect it. This was really handy as it was ready to sleep on straight away and didn’t need 24-48 hours to properly expand like a vacuum packed box one. The mattress didn’t smell of anything at all. There was none of that “new mattress” chemical smell I’ve noticed with foam mattresses in the past. The bed frame arrived in 3 parts (the headboard, the top head part of the bed and the bottom foot of the bed). It took the 2 man delivery team 15 mins to screw the headboard on the top part of the bed frame and slot it all together, it was that easy. The bed frame had a faint new furniture smell, but it was mild and faded quickly and wasn’t unpleasant at all. You can read my full Simba Jesmond bed frame review here.

What it’s made of

This is where the Source stands out. Simba shared the full specification with me, and the mattress is sourced and made in the UK. Working down from the top:

1. Cover: silky smooth cover made from plant-derived viscose with hidden tufting and polyester-based stitching
2. Wool comfort layers: 4 layers of 100% wool farmed in the UK, including Hampshire wool sourced under the Traceable British Wool Scheme in partnership with British Wool
3. Aerocoil micro springs: 1,900 titanium alloy springs in a king, made in Leeds
4. A further British wool layer for stability
5. Sprung base: 1,000 high-carbon steel springs in a king, made in Hampshire

There’s no foam in the specification which is great if you’re trying to avoid foam in your bedroom.

Why I love the British Wool

This is the part of the Source I’m most excited about. Using wool instead of foam is a great choice. It keeps the mattress foam free and made from natural rather than synthetic materials, and wool is naturally breathable too so helps to regulate temperature. Simba says all of the wool is farmed in the UK, a mix of British and Hampshire wool. Keeping the main material close to where the mattress is made means fewer miles travelled, which generally means lower transport emissions, and it supports British sheep farmers.

Simba also says its Hampshire wool is sourced through the Traceable British Wool Scheme, run in partnership with British Wool. The scheme is designed so that wool can be traced back to the individual farm it came from. In a world where “natural” and “eco” get used so loosely, that kind of traceability is exactly the transparency I want to see more of.

Fire safety

All mattresses sold in the UK have to meet fire safety regulations. Simba says the cover uses a bio-based fire retardant on the top surface and sides, which is and that there’s a fire-retardant layer at the base which is GRS (Global Recycled Standard) certified. GRS is a certification for products made with recycled material. 

Certifications

Simba lists GRS certification for the base layer and says its Hampshire wool is sourced through the Traceable British Wool Scheme.

How it felt to sleep on

View the Simba Source mattress

Simba says the Source mattress is medium-firm. Coming from a very soft bed, it felt firm but very supportive to me everywhere: my hips, my shoulders, all over. You lie on top of it rather than sinking in. Because I fall asleep on my side, that firmness was noticeable in the first part of the night and when waking up in the morning or middle of the night as I felt uncomfortable.

After a week, I added the Panda memory foam topper, and that made that extra bit of soft difference for me. This set up was now perfect for me and I really enjoyed the supportiveness of the medium-firm Simba mattress but with the topper for extra comfort. Panda describes the topper’s cover as 70% bamboo fibre and 30% polyester, but the topper itself is memory foam, so adding it brings foam back into an otherwise foam-free bed from Simba, which is not for everyone. It does list OEKO-TEX Standard 100 certification.

Sleeping on the Source mattress and with a topper I felt supported and my body felt more refreshed waking up in the morning, yet I was still able to feel comfortable and snuggle into the bed if I woke in the night. From someone who exercises a lot, I noticed my muscles felt less achey and I was able to get a more consistent 8 hours sleep, which aided my workouts and brain function and alertness during the day. For someone who prefers a firmer mattress that is more supportive without a topper, the Simba Source would be an excellent choice.

If you’re choosing the Simba Source mattress specifically to avoid foam and you know you like a softer bed, a wool or natural latex topper might be a better fit. Simba Sleep also offer great mattress topper options which you can find here. If you are a hot sleeper like I am then the Cool Foam Mattress Topper or the Hybrid Mattress Topper might be a good choice for you.

What impressed me:

• Temperature: I’m a hot sleeper, and this is the biggest difference I’ve noticed. I’ve been sleeping cooler and waking up with less hot sweats in the night, even with the topper on.
• Motion: I’m usually very sensitive to my partner moving in the night when the mattress bounces, and I haven’t been woken by it once on this mattress.
• Edges: The edges feel sturdy. I never felt like I might roll off, which I can’t say for some mattresses I’ve had.
• Supportive: I found the mattress to be really supportive and my body felt really refreshed waking up, increasing alertness during the day.
• A second opinion: My partner found it really comfortable, so if you already like a firmer bed, you may not need a topper at all.

How sustainable is it, really?

I look at every brand through the same lenses, and I try to separate what’s verified from what’s marketing.

What’s verified:

• B Corp certification. Simba has been a Certified B Corp since February 2023, with an overall score of 97.5 according to B Lab’s public directory. Its highest-scoring environmental area is toxin reduction (9.9 points). Its lowest are resource conservation (0.4) and land and wildlife conservation (0.3), which tells you there’s still room to improve on materials and end-of-life, but overall this is quite good. Scores are updated when companies recertify, so check B Lab’s site for the latest.
• British materials. Simba says the wool is British and Hampshire wool and the mattress is made in the UK. Shorter supply chains are a genuine plus as less carbon is generated shipping materials around.
• No chemical smell. This is my experience rather than a certification, but there was no smell at all from the mattress when it arrived which was great as other mattresses I have had there has been the off gassing ‘new and fresh’ smell.

What I’d like to see more of:

• Product-level certifications. There’s no OEKO-TEX, GOTS or wool welfare certification listed for this mattress. I’d love to see Simba publish how the wool is sourced and what animal welfare standards apply.
• Fire safety transparency. A clear statement on how the mattress meets UK fire safety rules, and whether any flame retardants are used.
• End-of-life. Simba says its mattresses are “suitable for recycling or refurbishment via specialist providers” and offers old mattress collection and recycling for a small fee. That’s helpful, but recycling a sprung mattress is complicated, so I’d like more detail on what actually happens to returned mattresses.

Side view of the Kingsize Source mattress

Close up of the Source Mattress and showing how the Jesmond headboard fits on the bedframe.

Is it worth the price?

At £1,399 for a king at full price, this is an investment. What you get for that:

• A 200-night trial. That’s long enough to know whether it suits you. Given that I needed a topper, it’s the feature I’d lean on most. I really liked this feature as you want to be sure that your mattress is perfect for you as sleep is so important and massively influences your life.
• A 10-year guarantee. You’ll need a mattress protector to keep it valid, which is an extra cost, but something I would hope everyone has anyway to protect from spills.
• A foam-free, wool and spring mattress made in the UK. That’s genuinely hard to find at this price from a widely available brand. This is perfect for anyone interested in a more sustainable option.

With the topper I really liked the Simba mattress and felt more refreshed in the mornings waking up from my sleep. I had a more consistent 8 hours and didn’t wake up in the night from partner movement, so I would say the investment is definitely worth it considering sleep has such a massive impact on every area of our lives. This would be the perfect mattress for you if you like a medium-firm and very supportive mattress. If you’re looking for a softer mattress whilst still being a natural option, then the Apex mattress may be a better choice as it has 7 layers of wool and comfort layers instead of the Sources’ 5 and gets a ‘Plush feel’ rating, although I haven’t personally tried this mattress.

Who it’s for, and who it isn’t

I’d recommend it if:

• You sleep on your back or front, or already like a firmer bed
• You run hot at night
• You’re a light sleeper who shares a bed and get woken by your partners movements
• You want to avoid foam and prefer natural fillings
• You value a UK-made product from a B Corp

I’d think twice if:

• You’re used to a very soft bed and don’t want to add a topper
• You want independently certified materials, such as GOTS or OEKO-TEX, on the mattress itself

My verdict

The Simba Natural Hybrid Source is one of the most thoughtfully made mattresses I’ve come across from a mainstream brand: foam-free, filled with British wool, and made in the UK by a certified B Corp. It kept me cooler than any bed I’ve slept on which made me feel more rested in the morning, and I haven’t been woken by my partner moving once.

On its own, it was too firm for me as a lover of soft beds, and I’d rather tell you that than pretend otherwise. With a topper on top, I’ve been sleeping better than I have in years and waking up with less body aches. If you like a firmer bed, you probably won’t need one. I still continue to sleep on this mattress as I really do love it, and I’m looking forward to continue to sleep on it for years to come as I know Simba’s reputation of outstanding quality will mean I won’t have to change my mattress every few years. And if you’re unsure about your investment, the 200-night trial means you can find out for yourself! 

Facts checked October 2026. Prices, trial terms and certifications can change, so check Simba’s website before you buy.