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4Sleep Mattress Review

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The 4Sleep mattress is the newest mattress start-up to join the growing family of online mattress companies. They were launched by a husband and wife team who have been making sleep products for 5 years. This gel memory foam mattress is being pitched as “the mattress that will forever change the way you sleep.”

But does it really live up to those expectations? We put the 4Sleep mattress to the test to find out how it performs in our in-home test. Continue reading below for our full review of the 4sleep mattress to find out.

In a rush? Click here to skip to the review summary for the quick version.


The 4Sleep mattress is a memory foam mattress built from 4 different layers of foam.

  • Top layer (gel memory foam) – this is a 1.5″ layer of gel memory foam. This layer has been specifically designed to sleep at the ideal sleeping temperature (which according to research and 4Sleep is in the 87-90 degree range). Like all memory foams, it contours to your body shape to help relieve pressure points and provide consistent support.
  • Second layer (response + energy absorption) – this 1″ foam layer strikes a balance to both absorb and minimize motion transfer, while also remaining responsive to your movements, providing a degree of bounce. Something of a transition layer between the support and comfort foams.
  • Third layer (deep compression support) – this 1.5″ foam layer is designed to prevent any bottoming out from the mattress helping reduce that feeling of being “stuck” that can sometimes accompany memory foam mattresses. Provides deep compression support, which is especially important for larger sleepers that put more pressure on the mattress.
  • Bottom layer (foundational) – 7″ of high-density support foam. Acts as a base and foundation for the mattress.
  • Edge support system – there is an additional layer that runs along the side edge of the mattress. This is 2.5″ foam layer helps reinforce the edges for both sleeping and sitting, preventing their collapse. Note: present only on the side edges, not the head or foot of the mattress.
4Sleep foam layers (top to bottom) - 1.5" gel memory foam, 1" motion control foam, 1.5" resiliency memory foam, 7" support foam.

4Sleep foam layers (top to bottom) – 1.5″ gel memory foam, 1″ motion control foam, 1.5″ resiliency memory foam, 7″ support foam. Viewing from the foot of the mattress.


The cover is fully removable and built from polyester, viscose, and Lycra. Lycra is the same material used in performance sportswear. The cover has a nice softness, with a feel similar to a soft blanket. The cover is quite thin, by design. The aim of the thin cover is to allow increased breathability and cooling. I’m a little concerned for the long-term durability given the thinness, however it does have a certain smoothness to the cover, which should prevent any catching or tearing while moving.

Aesthetically, this is one of the more different covers I’ve seen. Most covers are quite simple, with sharper lines and less style touches. By contrast, 4Sleep’s woven crisscrossing design strikes a bold retro statement. Personally, I prefer a more simple aesthetic, but I do commend 4Sleep for pushing forward modern mattress design.

Close of of the 4Sleep mattress cover

Close of of the 4Sleep mattress cover

Firmness, Comfort, & Support

The 4Sleep mattress is a 7 out of 10 on the firmness scale (where 10 is the most firm). This places it on the firmer end compared to most other online mattress companies (most sit at a 6 out of 10). For those sleepers looking for the slightly firmer feel the 4Sleep fills a bit of a void that has been present in the online mattress industry. The feel is similar to that of traditional memory foam, just not as extreme.

4Sleep mattress firmness level

4Sleep mattress firmness level

When you first lie on the mattress there’s a fairly firm feel. The mattress takes a few seconds to conform to your body. As it conforms you’ll feel a slight sinkage and hug along your body’s shape. There’s not an extreme sinkage, but you can expect 1-1.5″ of hug. At this point you would feel fairly stuck with most memory foam mattresses. The 4Sleep is more responsive and less “stuck” compared to traditional memory foam mattresses (however, it is less responsive than latex). That said, there’s definitely a feeling of pronounced body contour. It really takes the memory foam hug to the absolute edge. If it were any more pronounced it would fall into that crater-like “stuck” feeling. If you are a fan of memory foam feel, but just want something a little less extreme in the hug-department, you’d probably like the feel.

For a memory foam mattress it sleeps surprisingly cool. Many other memory foam mattresses I have tested tend to sleep a little bit warmer (even those supposedly optimized for heat issues). During my sleep test I didn’t feel like it slept warm.

Support was good as well. The mattress has been designed to be extremely durable and dense. This ensures support is always strong and consistent in any sleeping position. However, it also means the mattress sleeps more on the firm side. My back and body much prefers a mattress that’s closer to neutral firmness. As a result, the mattress created a few pressure points for me (especially in my lower back). That said, firmness is subjective. If you enjoy a slightly firmer support 4Sleep will likely meet your needs.

King sized 4Sleep mattress

King sized 4Sleep mattress

Sinkage Tests & Motion Transfer

Every review on Sleepopolis goes through a short series of sinkage tests. I created these tests to help show how the mattress performs under different types of pressure (sitting, lying, standing), which will help to give you an idea of the sinkage, hug, and feel you can expect.

See video below for specific information on the edge support system.

Lying position – in a normal lying position where my weight was evenly distributed in the middle of the mattress I saw 1-1.5″ of sinkage. Despite the fairly average sinkage (when compared to other foam mattresses), the feel of the hug and body contour was quite dramatic. It is not the extreme “stuck” feeling you get with older more traditional memory foam, but there’s definitely a strong body contour.

Sitting position (conservative) – in a conservative sitting position where I am sitting a bit further back on the mattress I saw 2.5″ of sinkage.

Sitting position (aggressive) – in a more aggressive sitting position where all of my weight is directly on the edge of the mattress I saw 4″ of sinkage.

Standing position – in a standing position, where I was positioned directly in the center of the mattress I saw 4.5″ of sinkage.

I was a little bit disappointed by these sinkage results, especially for the sitting position. It’s not that they are bad, but they are fairly typical of the average for foam mattresses. I expected a little bit better considering the extra edge support system built into the 4Sleep mattress. That said, the edge support system does provide extra support and stability when lying near the edge. However, for sitting positions it’s about average.

Motion transfer was quite good. Like most memory foam mattresses, it absorbs a great volume of energy and motion to help prevent sleeping partners from disturbing one another.

Angled view of the 4Sleep mattress

Angled view of the 4Sleep mattress


Sleepopolis readers always get the best discounts. Save an extra $75 off 4Sleep with promo code “SLEEPOPOLIS“.


Other Information

  • Shipping – free, comes in 2-5 days, compressed in a box
  • Warranty – 10 year, full replacement limited warranty
  • Trial – 100 days
  • Refunds – very easy, 100% money back guarantee
  • Made in the USA
  • Discounts – save $75 with promo code “SLEEPOPOLIS

Should you buy the 4Sleep mattress?

4Sleep has positioned itself as a fairly unique mattress in the online mattress market. From its design to material usage and layered construction, it’s a well built mattress with a feel completely its own.

I would recommend the 4Sleep mattress to anyone who falls into the following categories:

  • You want a moderately firm mattress – the 4Sleep is a 7 out of 10 on the firmness scale (where 10 is the most firm). You absolutely must like the feel of a slightly firmer mattress to enjoy 4Sleep.
  • You want a pronounced hug and body contour – while not as dramatic as the older school memory foam mattresses (IE, Tempurpedic) the 4Sleep mattress does have a pronounced body hug. The sinkage results are fairly average, at a 1-1.5″ in a normal lying position. However, you may feel a bit enveloped by the lower response of the contouring foams.
  • You want slower responsiveness – I wouldn’t describe this as a bad attribute, but it’s certainly something to consider. This memory foam isn’t not responsive, but it’s also not highly responsive either. Once the foams contour to your shape they will want to keep that shape. The do respond quicker than very traditional memory foam, but not as quickly as latex, Avena, or other foams. It doesn’t create a dramatic “stuck” feeling, but it does ride the edge of deeper contouring vs. faster response time.
  • You want memory foam + good cooling – many memory foam mattresses struggle with heat retention. The gel top layer of the 4Sleep does a pretty good job of keeping heat in check. At no time in my sleep test did I feel that the sleeping surface was uncomfortably warm.

Visit for more information on the 4Sleep mattress. If you decide to go with 4Sleep make sure to use our exclusive promo code for Sleepopolis readers. Use code “SLEEPOPOLIS” to save $75 on any 4Sleep order.

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