Amerisleep is one of the veterans of the online mattress industry. Amerisleep has been building great mattresses for almost a decade and has been selling them online since 2010. During the last 10 years they’ve developed some of the most high-quality foams, innovative materials, and well-made mattresses on the market.
For this Amerisleep mattress review we’ll be looking at their AS4 mattress. Continue reading below for our full review or skip to the review summary if you’re in a rush and want the quick version.
On the softer side, the AS4 could be a great pick for side sleepers! Get $250 off your AS4 purchase with our exclusive discount!
How does the AS4 Compare?
The Amerisleep AS4 mattress is the second softest option in the Amerisleep line, sporting a very plush and luxurious feel. The AS4 features construction aspects that are common in the Amerisleep line, such as Celliant covers, Bio-Pur foams, and SMT technology.
Amerisleep has 5 models total, the others being the AS1, AS2, AS3, and AS5. The AS4 (formerly known as the Colonial) has a plush yet supportive feel, and could work for any type of sleeper – though it’s probably best for side sleepers or people that prefer a plush feel.
Like the sound of Amerisleep? Check out our complete review series on all 5 Amerisleep mattress models
The AS4 is designed to be the second softest in the Amerisleep line. The mattress is an all foam construction made of three layers totalling 12 inches in height. The feel of the mattress comes from the thick comfort layer of memory foam, which allows the sleeper to sink deep into the mattress for pressure relief.
Cover – The cover for all of the mattresses in the Amerisleep line is made of a soft blend of polyester, Celliant and spandex. It’s a stretchy material that snaps back into place quickly, so you won’t have to worry about the cover bunching up when you change positions on the mattress. I should mention that there is some evidence that Celliant provides some benefits for muscle recovery. I don’t have the expertise to go into detail on the science behind these studies, but if that interests you I recommend doing some research on the subject
In terms of the feel of the cover, I found that it had a bit of thickness to it, which made it pretty soft. As I pushed into the top of the mattress I could feel some airflow through the cover, which shows it has some breathability to help with cooling.
Comfort – The comfort layer of the AS4 is made of a 4 inch layer of memory foam. This layer will allow the sleeper to sink in for pressure relief and provide the classic memory foam feel of contouring to the body. Amerisleep uses a memory foam with an open celled structure in all of their mattresses to aid in cooling of the mattress as memory foam can be known to trap too much heat at times. I should note that Amerisleep uses plant based materials in their memory foams, which helps cut down on the use of petroleum in the construction.
Transition – Below the comfort layer is what Amerisleep calls the Affinity layer. It consists of a 1 inch layer of poly foam that has a convoluted (eggshell) design. This design creates space to allow air to flow through the mattress for improved temperature regulation and cooling of the mattress. This layer is a bit firmer so it acts as a transition layer between the comfort and base layers of the AS4.
Base – The base of the mattress is made of 7 inches of high density poly foam. This layer is firm to act as the foundation of the mattress and provides deep compression support to the sleeper. The base also provides the mattress with its shape and some durability to the overall structure.
When I first pressed into the mattress I felt the classic memory foam feeling of the mattress contouring to my hand. The comfort layer is pretty thick and has a slow response to pressure, so I could see the outline of my hand on top of the mattress when I removed it. When I applied more pressure and used both hands to press into the mattress I was able to sink further into the comfort layer, but it is so thick that I didn’t really interact with the firm base.
Different body types and sizes cause everyone to feel the firmness of a mattress a little differently. Because of this I wanted to give a few more opinions on the firmness of the AS4 so I brought in 3 more testers to try the mattress. This range of opinions should help to give you a better idea of what you can expect from the Amerisleep AS4.
The opinions on the firmness of this mattress varied quite a bit, as you can see from the chart above. A 6.5/10 is generally considered to be a medium firmness so the range from 5.5/10 to 7.5/10 is pretty surprising. I personally rated the AS4 as a 6.5/10 on the firmness scale and was surprised to find a mattress with such a thick layer of memory foam on top to have a medium firmness. I think that this range in opinions on the firmness of the AS4 shows exactly how vastly different opinions on the feeling of a mattress can be due to size and sleep preference.
Instead of just describing how the AS4 feels I wanted to give a visual representation of where someone may feel pressure points while lying on the mattress. To do this I placed a pressure map on top of the mattress and lied on my back, side, and stomach. On the image below pressure will be represented from blue (low pressure) to red (high pressure).
When I lied down on my back I got the initial feeling of the memory foam comfort layer, which can initially feel a bit firm but will eventually allow you to sink in as your body heat and weight press into the material. This position allows me to evenly distribute my weight and the pressure map results above show low pressure across my body. As I was lying there for a bit longer I did feel like I was sinking into the mattress more so than sitting on top of it however, even with the slow response to pressure of the memory foam, I found that I was able to adjust my position and didn’t feel stuck in the mattress.
Once I rolled onto my side I found that I was pushing further into the mattress due to an increase in weight concentration in that position. Because of this increase in weight concentration side sleepers want to be aware of pressure points that can form, especially at the shoulders and hips, while lying on a mattress. The pressure map results above show only a slight increase in pressure on my side and I would credit that to the thick comfort layer of memory foam. Thick memory foam layers tend to be great for side sleepers as they allow them to sink further into the mattress for pressure relief and I can say that I felt very comfortable in this position on the AS4.
Side sleeper? Check out my best mattress for side sleeping picks.
The pressure map results above show low pressure across my entire body when I rolled onto my stomach, something that is especially important at the chest in this position so that it is easy to breath. I will say that I did feel my hips sink into the mattress a bit, which put a bit of an arch in my back. Stomach sleepers tend to prefer firmer mattresses as they keep their hips from sinking in and their backs in a better position. If you are a strict stomach sleeper I would probably recommend taking a look at one of the firmer versions in the Amerisleep line.
If you plan on sharing your bed with a partner then you will want to know what it will feel like when there is motion on the other side of the mattress. This next test is helpful in showing the intensity of disturbance that is detectable from one side of the bed to the other.
For this test I dropped a 10 lb steel ball from heights of 4 inches, 8 inches, and 12 inches, to simulate someone changing positions or getting into bed, and measured the disturbance on the other side of the mattress. This should be pretty intuitive: the bigger the lines, the bigger the disturbance.
The 4 inch drop simulates someone rolling around in bed and shows a small amount of motion transferred across the mattress. I would say that this is a very good result when compared to other mattresses that I have tested. While the 8 and 12 inch drops cause higher levels of disturbance, these are still good results when compared to other mattresses I have reviewed. I credit the thick memory foam comfort layer with dampening the disturbance and isolating the motion of these drops.
Many people buying a mattress will want to know whether they’re going to feel like they are more on top of the bed or sinking into it. To better understand how someone might sink into a mattress, I use four balls of varying sizes and densities (a 6 lb medicine ball, a 10 lb steel ball, a 50 lb medicine ball, and a 100 lb medicine ball) and place them on the mattress to measure how much they compress the surface.
These different sizes, weights, and densities help to imitate different body parts or different sized people to show how far into a mattress you may sink.
- 6 lb medicine ball: 1.5 inches of sinkage.
- 10 lb steel ball: 2.5 inches of sinkage.
- 50 lb medicine ball: 5 inches of sinkage.
- 100 lb medicine ball: 6.5 inches of sinkage.
If you’re going to share a mattress and need to use the entire surface then edge support is something you are going to want to take a look at. Foam mattresses sometimes struggle to live up to the edge support of traditional innerspring mattresses, so I wanted to have a look at how I would feel near the side of the mattress.
While lying on my back near the side of the AS4 I found that the feel of the mattress stayed the same on the side as at the center. The image above shows that when I moved to the edge of the AS4 there was some compression, which is expected out of a softer memory foam, but I found that I felt secure and that my weight wasn’t collapsing the side of the mattress.
When I rolled onto my side I found that the AS4 allowed me to sink in and provide contouring to my body, shown above, while still being supportive near the edge. I again saw compression through the soft memory foam, but didn’t feel like I would fall out of bed.
Once I sat up on the edge of the mattress and concentrated all of my weight over one section of the side I saw a good amount of compression through the comfort layer. Even with the compression through the comfort layer I found that the structure of the mattress held up well overall.
- Sleep Trial: There is a 100 night trial period for this mattress.
- Warranty: Amerisleep offers a 20 year warranty.
- Shipping: The mattress ships free to the contiguous United States and will arrive compressed in a box.
Size and Pricing Information
If you’re convinced the Amerisleep AS4 is for you, click here to save $200 off!
|Twin||38" x 74" x 12"||56 lbs||$1,399|
|Twin XL||38” x 80” x 12”||62 lbs||$1,449|
|Full||54” x 74” x 12”||79 lbs||$1,549|
|Queen||60” x 80” x 12"||94 lbs||$1,699|
|King||76” x 80” x 12”||119 lbs||$1,899|
|California King||72” x 84” x 12”||119 lbs||$1,899|
|Split King||38" x 80" x 12" (x2)||62 lbs (x2)||$2,698|
Now that we have gone through the full review of the AS4 it is time to discuss who I think it would be a good fit for.
- Memory Foam Feel – We saw during the construction portion of the review that the comfort layer of the mattress is made of 4 inches of memory foam, which is going to allow you to sink in and give the classic memory foam feel of contouring to the body.
- Side Sleepers – The comfort layer allows side sleepers to sink deep into the mattress for pressure relief. Further proof of the AS4’s value to side sleepers was shown in the pressure map portion of the review, where there was only a slight increase in pressure when I rolled onto my side.
- Couples – The AS4 performed very well on both the edge support and motion transfer portions of the review, which are the two portions I reference most for those looking for a mattress to share with a partner.
- Edge Support
The second softest mattress in the Amerisleep line, the AS4 has 4 inches of open cell memory foam for a comfort layer. This layer allows sleepers to sink deep into the mattress for great pressure relief, making it an excellent choice for side sleepers.
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