The basic functions of a mattress - overview

How Mattresses Function

A mattress in its simplest form is a sleeping system with different parts which work together to do two main things. These are to provide you with comfort and provide you with support in all your different sleeping positions. That’s it … everything else is secondary to these.

For comfort, which is mainly about pressure relief, your mattress needs to conform to your body shape and form a cradle that is deep enough to spread your weight over the surface of the mattress and relieve pressure points. We call this sinking IN. This is the role of the top part of your mattress or what is called the comfort layers. This may include one or more thinner layers and includes any quilting which is on the very top of your mattress.

For support, which is mainly about spinal alignment, your mattress needs to control how far different parts of your body sink DOWN into a mattress. This is primarily the role of the lower parts of your mattress or what is called the support layers. There may be one or more support layers and together they are called the Core of your mattress.

Sometimes in certain types of mattress constructions there can be a middle layer which helps with both pressure relief and spinal alignment. This is called a transition layer and contributes to both the comfort and support of your mattress.

Note that sinking in is not the same as sinking down. Sinking IN means how well a mattress forms a cradle to your body shape and is necessary for pressure relief. It is only possible with the upper layers. Sinking Down is all about how deeply different parts of your body sink into a mattress in total regardless of the cradle formed by the upper layers. It is affected by all the layers of a mattress and is primarily concerned with spinal alignment. Two examples will make this clear. If you lie in water it will form itself to your body shape. This is sinking in. If you lie in a hammock, there is no cradle and you may have pressure points even though parts of you are sinking lower than others. This is sinking down.

The middle layers of a mattress play a dual role and can help to differing degrees with both sinking-in (for pressure relief and comfort) and sinking-down (for spinal alignment and support) depending on the construction of the mattress. Thinner comfort layers often need the help of the layer below it to form a cradle that can relieve pressure. Thicker layers do not need as much help so the layers below can be firmer and primarily concerned with holding up the heavier parts of your body to ensure spinal alignment.

When a middle layer helps more with pressure relief, we call that a “progressive” mattress construction. When a middle layer is either not there at all or is not needed for pressure relief and contributes more to support, we call that a “differential” construction. More about these in another section.

It’s rather amazing that in all the hype and misinformation that exists in the industry that these two basic fundamentals have been all but forgotten and/or complicated beyond recognition. You will often hear about how comfortable an innerspring may be when in reality it is a support layer that only “helps” with comfort in certain cases. All innersprings are primarily concerned with the support qualities of your mattress. Comfortable innersprings is mostly just “sales talk”.

You will also often hear how supportive a comfort layer like memory foam is. This too is pure “sales talk” since the upper layers are primarily about pressure relief not support and in the case of memory foam it has little ability to support at all and is completely dependent for this on the non-memory foam layers below it. Remember that Upper comfort layers = pressure relief/comfort and lower support layers = spinal alignment/support and middle layers can help with both.

Mattress Materials and Comfort.

In the following sections, you will read all about these two functions from different perspectives and how different types of people need different combinations of layers and materials that work together in different ways to give you enough of both to fit your own unique needs and body weight and profile.

In general terms … when you hear someone talk about “firmness” … they are (or should be) talking about the deeper layers of a mattress. When you hear someone talk about “softness” they are (or should be) talking about the upper layers of a mattress. Those who don’t understand the difference between the roles of the different mattress layers and who “confuse” the issue by talking about a mattress as if it is either all “soft” or all “firm” shouldn’t be selling mattresses. Even by the end of this first article, you will probably understand more than they do.

ALL mattresses are made up of different layers with different degrees of both softness and firmness in the different layers. The softness and firmness of foams is measured using a term called ILD (also called IFD). Lower numbers are softer and higher numbers are firmer. The range in more commonly understood terms is approximately as follows … bearing in mind that softness and firmness itself is very much based on individual perception.

Softness/ Firmness XX soft X soft soft med. soft medium med. firm firm X firm XX firm
ILD Less than 14 14 - 17 18 - 22 23 - 27 28 - 32 33 - 37 38 - 42 43 - 47 More than 47

So let’s take a quick look at what each of these really are and how they relate to all the words, ideas, and advertising hype you will be exposed to as you begin your search…


Comfort is mainly the ability of a mattress to form a cradle that is deep enough to spread your weight over the surface of your mattress to relieve pressure points. Nothing more than this… If you are lying down on an unforgiving floor, all of your weight is bearing down on just the few points of contact between a rounder you and the flat floor. Most of your weight would be on your hip and shoulder area on your side, on your rear end and upper back on your back, and on your pelvic or stomach area and chest on your stomach. Without any contouring, the points that are bearing your weight will likely get more than a little sore once you lie there for a while.

On the other hand, if you lie down on a piece of wood that was perfectly contoured to the shape of your body, it would feel very soft because your weight would be spread out over a much larger area. Now granted it wouldn’t feel very soft as soon as you moved and shape of your body that was against the wood changed since the wood wouldn’t change along with you, but as long as you were perfectly still it would relieve any pressure on the different parts of your body. Most of us have had the experience of going to a favorite place on a sunny day and finding the “perfect rock” to lie on in the sun. Sometimes we have fallen asleep for long enough to wake up with a sunburn. This is another example of how good weight distribution can be very comfortable no matter how hard or soft the material we are lying on. In other words, pressure relief and the feeling of comfort that is connected to it is dependent on a mattress’ ability to form a cradle around you that conforms to your shape, is deep enough to fill in the gaps, and changeable enough to make a new cradle every time you move. This is the basis of pressure relief and requires sinking IN. The top few inches of a mattress or what we call the comfort layers is the part of a mattress that does most of this (if you have any doubts of this just imagine putting a piece of plywood on the best conforming innerspring or foam in the world and guessing how you would feel).

The main reason for the different materials used in the comfort layers of a mattress is to spread out the pressure of your weight in many different sleeping positions. Each type of material does this a little differently and some are better than others. We will explore all of these in the different sections.


Support is the ability of a mattress to keep your spine aligned while you are sleeping. What exactly though does “spinal alignment” mean? In simple terms, it means that while you are sleeping your spine needs to be in the same alignment as when you are standing up straight with good posture. When you look at someone’s spine from the front, you will see that the spine is very straight and doesn’t “bend” from side to side. This means that when someone sleeps on their side, their mattress needs to keep their spine very straight. On the other hand, if you look at someone’s spine from the side, you will see that it forms a natural “S” curve with the small of the back and the neck bending inwards and the upper back and the pelvis bending outwards. This means that someone who sleeps on their back or stomach needs a mattress that keeps their spine in this natural “S” shape while they are sleeping. This means that heavier parts of your body need to be “held up” or they will be too low and other parts of your body need to be allowed to “sink down” or they will be too high.

Different mattresses or combinations of firmer and softer materials are better or worse at doing this, especially when you consider that very few people sleep in the same position all night long and that their support needs change constantly through the night as they change position. Some materials and types of mattress constructions have a larger range of positions that they can keep you in alignment than others. A mattress that doesn’t allow parts of you to sink down far enough to have proper alignment and a mattress that allows parts of you to sink down too far for proper spinal alignment would both give you poor support. The myth that firmer mattresses offer better support is long gone as more people recognize that spinal alignment needs a mixture of softness and firmness and is interconnected with how well a mattress relieves pressure. The support core of a mattress is mainly responsible for support as it controls how far you sink DOWN beyond the point that you sink IN to your comfort layer and keeps your spine aligned.

There is a second part of support though and that is holding up the more recessed (and generally lighter) parts of your body that don’t come into contact with the support core so they don’t “collapse” because there is only air underneath them. This second part of support is also a function of the upper cradle as it allows you to “fill in” these gaps by using better materials in the comfort layers that can “push back” to differing degrees and hold them up. This is an important part of supporting the lumbar area of your body as this is usually the biggest gap in your profile.

Comfort and Support

In your search for a mattress, never forget that these two things … comfort and support … are what you are looking for … together. Softness, firmness, coil count, zoning, coil gauge, ILD, and all the thousands of other “words” you will hear while you are looking for a mattress will almost all boil down to these two things. If someone tells you something or uses a buzz word that makes little sense to you, simply ask them either …

A. Does this “word” somehow make the mattress contour to your body better in all your sleeping positions and adjust itself while you move? How exactly does it do that?


B. Does this “word” somehow make the mattress keep your spine in better alignment in all your sleeping positions and adjust itself while you move? How exactly does it do that?

A third question that is increasingly important in these days of lower quality materials is “how long will it last before it stops doing what it does in your showroom?”

What you are looking for is a mattress that lets you sink IN enough to form a cradle, relieve pressure, and fill in and hold up your recessed parts, while at the same time controls how far each part of you sinks DOWN into the mattress to keep your spine aligned and “support” the cradle above it. If you are in any doubt about what you are being told (once again bearing in mind that after this article alone you may know more than many mattress salespeople), just come back here or to our forum to find out the truth behind the words.

The benefit of a basic mattress education.

Most importantly, take your time and don’t worry about missing some great “sale”. They are mostly fake and meant only to get you to buy before you leave the store and do some comparisons. You will find out how they work as well and how you can save more than any sale by knowing where to go and who to buy from. Some basic education about mattresses and where to buy them will save you much more than any sale, both in terms of money and in terms of how well you sleep for the next few or many years.

So now that you know the 2 basic functions of a mattress … let us move on to the overviews for the different sections.

  1. The different types of mattress support cores … and their similarities and differences.
  2. The different types of mattress comfort layers … and their similarities and differences.
  3. The different ways that the layers of a mattress are put together and work together.
  4. How your preferences, sleeping style, and statistics can affect your personal choices.
  5. Using what you know in a simple five-step approach to choosing your perfect mattress.

We recommend that you read the overviews in order first and then go back and read the individual pages in each section if you need more detailed information as they have been designed to be more informative and “progressive” in that order. As in all things, however, feel free to scan them in any order you prefer.

Don’t forget that our forum is always there to help you at every step along the way.

jThis is all very helpful information but I have a problem. I am 6’ 220 pounds and my wife is 5’2" 110 pounds and I like harder mattresses and she likes softer mattresses. We made the mistake of purchasing the softest mattress they sold at American Signature Furniture when we furnished our home and 2 years later I have serious back pains because the mattress stinks. It literally bends in half when its lifted off the bed to rotate or move.
Since we both enjoy different styles we decided on a sleep number bed. I like my side just fine and my number is 55 - 60 and i sleep comfortably with no back pain in the morning. My wife hates her side and wants it removed asap. She says it’s only an air mattress (which it is) and she hates the way it feels.
We went to Sleepy’s and both liked the Kingsdown MySide Series 6 Red and Gold since it provided a firm support for my side and soft support for her side. However, I am skeptical that the value is worth the price and I am overpaying for the product that could be replicated elsewhere.
Do you recommend any stores in the Philadelphia area that we should go visit, and, brands/beds we should test that have varying supports on both sides of the bed?

Hi Justin … and welcome

First of all I should mention that the “air bladder” mattresses IMO offer very poor value and should be avoided. They are not a good choice for a support layer as other materials are available that “naturally adjust” to different sleeping positions far more effectively than air. For an “in depth” look at airbeds or air bladder type mattresses … there is an article here which goes into some detail. At best they may be OK for some people who only sleep in one position but even then I believe they are not a good choice compared to many other options.

There are many manufacturers who are offering side to side split constructions in their mattresses and these are especially common in some of the better online factory direct manufacturers such as some of the members here. Even most local manufacturers who have an actual factory would be able to do this and have been doing it for years. Some of the mattresses available in chain stores and other outlets are just starting to do this now but at outrageous prices. The Kingsdown MySide series 6 is among these. It has an unbelievably horrible 8" of polyfoam and a meaningless 1/2" layer of memory foam above the coils … and I’m amazed they have the nerve to sell an entire mattress worth of polyfoam over an innerspring for this price. This mattress caters to the worst trends in the industry today and the only thing that even remotely justifies the price (even if it was 70% off the listed retail) is that it has a feature that has been available for years through independent manufacturers, many of whom can make a mattress any way you may wish.

Post #4 here was also in response to someone who was looking at the Kingsdown Series 6 in Philadelphia and has some information and local outlets that should be helpful.


A little over a year ago, my husband and I bought an American Signature mattress from Value City. After a couple of months, his side seemed to cave in. He is 6’ and 225 pounds and there is was a definite difference between our two sides. That indent would cause my weight to shift more toward his side and was a very uncomfortable sleep. I called VC and they sent someone out and on his recommendation they replaced our mattress. It as the same mattress and within one week, it was already beginning to make the crater. If he leaves the bed and I roll over, its like falling in a small hole. is this what I can expect from buying a mattress if they are designed to “sink in”? I would appreciate any input before I call VC again. Thank you!

Hi Louana,

What you are experiencing is unfortunately all too common today with so many mattresses that use either low quality polyfoam or memory foam in the top layers of the mattress (which is the weak link in all mattresses). Low quality memory foam especially (which is what I assume you bought) is prone to this. This is especially a problem with people who are heavier as the foam will become softer faster.

While every mattress doesn’t use these low quality materials … the better ones are usually made by smaller independent manufacturers and/or the sleep shops who sell them who tend to use much higher quality materials than the major brands or mass market outlets and sell them at better prices.

These guidelines should help you avoid most of the traps and pitfalls of mattress shopping and eliminate 75% (or more) of the mattresses that most consumers would otherwise consider or purchase. The better value and quality would be in the much smaller percentage that is left.

While this would involve a little more research and searching … the effort will be well worth it. If you let me know the city you live in … I’d be happy to take a look to see if I know of any independent manufacturers or quality outlets that are near you.


I just bought an Englander “Hotel Collection” king size and I am very unhappy. I replaced a Searns and Foster that was as hard as a rock. Do you recommend any retailers or brand king size mattresses in the Franklin/Brentwood (Williamson Co) Tn. area, zip 37067. What do you think of the Hotel Collection sold at Macy’s? I can pay up to $2500- $3000. Thanks

Hi Glenda,

There are really no specific brands that I recommend because the quality or value of a mattress has nothing to do with the brand and everything to do with the materials that are in it and the quality of construction. Because of this … I pay far more attention to knowing the materials in a mattress than I do what name is on it.

This is also the reason that where you buy a mattress is far more important than the brand as well. Sources which will identify what is in every layer of every mattress that they sell and have the knowledge and desire to tell you the truth about the types of material that are in their mattresses and the advantages and disadvantages of each material are the only places where it is worth spending your shopping time. When an outlet does this … they are encouraging comparison shopping based on materials and construction rather than brand or advertising copy and the odds are much greater that the quality and value they provide is better. They will teach you how to tell the real value and quality of a mattress instead of trying to convince you that a certain mattress is better than another without any facts to validate their story.

This is the reason for the guidelines here that I put together which will help you avoid the vast majority of poor choices when you are mattress shopping and focus on buying a mattress that has real quality from an outlet that will help you understand how to choose rather than convincing you what to choose based on brand or a story that has no substance behind it.

As an example. in the case of the lowest priced Macy’s hotel collection … you are paying $2499 for a mattress that has only 1" of latex and all the rest of the foam is much cheaper and lower quality polyfoam. This is typical of the construction of a mattress that should cost much less than the “sale” price of this mattress and that could be purchased from a smaller local or regional manufacturer that uses similar materials. The other higher priced models that do use more expensive materials (such as silk wool fibers, cotton, or thicker layers of latex) are similarly overpriced. This doesn’t mean they are “bad” mattresses … only that they have poor value compared to other similar mattresses that are sold through smaller local or regional manufacturers either factory direct or through smaller sleep shops. These are the types of mattresses and outlets that I would tend to avoid.

Your budget is certainly in the range where you could purchase a high quality mattress using some of the best materials if you choose an outlet that is either factory direct or deals directly with a local manufacturer, has a shorter supply chain and offers true value as well as the knowledge and willingness to tell you exactly what is in every layer of their mattresses and will help you choose a mattress that is best suited for you without trying to “upsell” you into something that only serves their profit margin.

Unfortunately there are no factory direct outlets near you that I am aware of however there are some local wholesale manufacturers which sell mattresses through local outlets and have models that use good quality materials and construction and have better value than larger national brands. While some of these may offer better value … it is especially important when you are not dealing directly with a manufacturer that the outlet where you are testing mattresses provides you with the layer by layer specifications of any mattress they sell so you can tell what the “weak link” of a mattress may be and can make sure that they don’t include more than an inch of low density soft polyfoam in the comfort layers or quilting of their mattress. This also makes it possible to make more meaningful value comparisons between different mattresses.

Local Wholesale Manufacturers: Local wholesale manufacturer that sells through local outlets. They make a range of mattresses using a variety of materials and have an store finder on their website. Local wholesale manufacturer that sells through several local outlets. They also make a range of good quality mattresses. These may offer good value depending on the prices charged by the retail outlet. They also have a retail store finder on their website. Local wholesale manufacturer that also sells through local stores. They make a range of mattresses of all types and also have a store finder on their website. They are one of the larger independent manufacturers but there may be some difficulty in finding out the materials in their mattresses and I have seem many cases where pricing is higher than I would pay. Some retailers however will provide the specs of their mattresses and some may have “better than average” value. Local licensee of Restonic and Springwall. Restonic also has a store finder on their website. They make some good quality mattresses but the specs are different in different areas of the country so a spec sheet is especially important to find out how much polyfoam they are using in the upper layers of their mattresses.

Out of the local wholesale manufacturers … I would tend to focus on outlets that carry Jamison and Dutch Craft which are privately owned locally based manufacturers and generally use good quality materials in their mattresses. Of course their value will depend on the retailer that sells them. Some of the other manufacturers mentioned on the list may also have good quality/value as well on a mattress by mattress basis.

In addition to these options it may be worthwhile to consider an online purchase from a factory direct outlet such as some of our manufacturing members here because they can be a good source of quality and value when the choices at local outlets are more limited or not in the same value range as an online factory direct manufacturer. At the least they can provide a good value reference point. In this case it is still very valuable to do some local mattress testing first to get a clear idea of the type of mattress and layering that is suitable for you to help provide you with some guidelines for an online purchase.

Some of the local outlets that may carry higher quality or value mattresses made by smaller regional or national manufacturers or local brands and some of the manufacturers they carry which I would tend to focus my testing on include … Nashville, TN. Southerland, Bed Boss, mLily. I have talked to Tim here and he has been in business for many years. He knows his foam from experience, weight, and “feel” more than technical specs (like many people with years of experience in the industry) Nashville, Knoxville, TN. They carry Savvy Rest component latex mattresses which use very high quality materials (organic Dunlop, 100% natural Talalay, and wool quilted organic cotton covers) but I would make some careful “value” comparisons here because they are also in a significantly higher budget range than many other similar component latex mattresses. Antioch, TN. Southerland, Sleep Harmony. Talked with them and they sell Southerland latex hybrids for reasonable prices (unlike some retailers) and understand the importance of specs and will get them without question for those who ask. Good people. Glideaway/Sleep Harmony can also be a good value choice. Retailer with stores in Nashville and Hermitage, KY. Carries their own line of private label memory foam and latex mattresses called Sleep Natural that may include some better quality/value options. I would avoid the major brand and liquidation mattresses that they also carry. Goodlettsville, TN. Restonic Franklin, Murfreesboro. Englander, Restonic Franklin, Lebanon, Carthage, Lafayette, Cookeville. Dutch Craft Hendersonville, TN. Capital Bedding Smyrna, TN. Englander. Spring Hill, TN. Jamison. Will provide foam density specs for their customers and seem to be informed and helpful. Murfreesboro, TN. Dutch Craft Murfreesboro, TN. Restonic

This should give you some of your better local options. In all cases though it’s important to make sure the retailer you are dealing with can provide you with the details of the mattresses they sell so you can make meaningful comparisons.

If you have any other questions along the way … feel free to post them.



I have read and ;learned a lpot from your site and am locked into an exchange on a Serta mattress. There are two choices and I am trying to make the decision as to which is more suitable. One has support layers as follows; 1.5 inch comfort foam- unknown what type,3" hi IFD support foam (exact number and type unknown + an additional 1" comfort foam. This is called “Firm”… Second mattress: 1"comfort foam +1" Hi IFD support foam, again number and type unknown, then 3" convoluted topper. They call this “Plush” . I cannot get any more information (my mistake in not knowing about your site earlier) and need to make a choice. I can sell this mattress and go to a mattress maker if it does not work out, but need to pick. I am 5 6, 135 lbs, side sleeper Thanks for any info. I realize these are not ideal specifications but I do not have access to further info. THe support core is continuous innerspring of decent gauge and count. I am afraid the one with 3" of hi IFD will be way too rigid. But I am not sure what a convoluted topper is!

Thanks for any help

Hi Mamie,

Unfortunately you are in a difficult situation where you are locked into an exchange where there may be no good choices. Post #2 here includes some information and suggestions and links to threads with suggestions to other members who were in the same situation and some of the ideas that can help make the best of a bad situation.

The description of the mattress doesn’t include any information about the quality of the foams in the mattress but I can tell you that they are not good (in the range of 1.3 lbs density which is low quality).

If you let me know the store you are dealing with I’d be happy to take a look to see if they may have any reasonable options that may be worth considering.