Hi bedfortallperson,
You can see my “definition” of healthy sleeping in post #4 here.
As far as the “safety” of different materials … the most reliable way to assess this would be the certifications and testing that has been done on them for harmful substances and VOC’s. The most common certification for polyfoam and memory foam is CertiPur (which is an industry sponsored certification) and latex is usually certified by either Oeko-Tex or Eco-Institute which are both independent testing protocols and have more stringent testing standards.
The issue of mattress safety is a complex one and there is a great deal of either exaggerated information or misleading information in the industry on both sides of the argument (whether it’s the natural/organic side of the industry or the parts of the industry that discount or minimize any concerns about the safety of mattress materials and components). There is more about all of this in post #2 here and the additional posts and sources of information that it links to which can help answer the question of “how safe is safe enough for me?” on an individual basis.
The choice of materials and components in a mattress is a personal preference and each person may make a different choice that is better for them. Each type of material or foam (polyfoam, memory foam, or latex foam) has pros and cons that may be attractive to some and not to others in terms of feel, performance, or durability.
You can read more about some of the pros and cons of latex in this article and more about the pros and cons of memory foam in this article and more details about how they compare in post #6 here.
While any material that is certified with a reputable certification standard would be “safe enough” for most people … there are some who may be more sensitive to some materials than others (who may have medical issues such as MCS or have other personal reasons for avoiding most synthetic materials). Anecdotally … there are more people who have sensitivities and reactions to memory foam than there are who have sensitivities or reactions to polyfoam and latex would be the least likely to cause issues although there are some that can have sensitivities or even allergies to latex as well (there is more in post #2 here about latex allergies or sensitivities) although this would be quite rare with the type of latex used in mattresses vs dipped latex such as rubber gloves or condoms.
Latex foam certainly has performance, durability, and breathability benefits that make it attractive to many people and for these the higher cost would be well worth it. I would also keep in mind though that the most important part of any mattress is how well it matches your specific needs and preferences in terms of PPP (Posture and alignment, Pressure relief, and Personal preferences) and the type of material isn’t nearly as important as the specific design of a mattress that uses them. There are latex mattresses that work very well for some people in terms of PPP that would be a completely unsuitable design for someone else to sleep on. The same is true about any other material or type of mattress. If a mattress isn’t a good “match” for the person that buys it in terms of PPP then it would have little value for that person. A mattress that “causes” a back ache or discomfort for one because it’s an unsuitable design may be the best possible mattress for relieving back pain for someone else (to the degree that a mattress can help with this).
The next most important part of a mattress purchase is the durability of the materials and whether there are any obvious weak links in the materials or design. No matter how well a mattress matches your specific needs and preferences at first … if there are low quality materials in the comfort layers especially … they will soften, compress, or break down much more quickly than higher quality and more durable versions of the same material and a mattress that you hoped would last you for a decade may only last you for months or a few years. There would be little value in spending a great deal of money … in some cases several thousand dollars … only to find out that you could no longer sleep on it in a very few years. When you buy a mattress then it’s always important to make sure you know exactly what’s inside it (see this article) so you can identify any low quality materials and make more meaningful comparisons with other mattresses. I would never assume that a higher priced mattress uses better quality materials because in the mainstream industry especially this may not be the case.
After PPP and durability … the other parts of your personal value equation that are important to you would also be a significant part of the “value” of a mattress purchase.
I would also be very cautious with using mattress reviews as a source of reliable information because they will tell you little to nothing about whether a specific mattress is a good match for you in terms of PPP and they usually say nothing about the quality of the materials inside it (see post #13 here for more about reviews).
The “best” way to choose a mattress I know is the tutorial post here which has all the basic information, steps, and guidelines that can help you make the best possible choice for you, know how to test a mattress for PPP, and know how and why to avoid the worst choices. It also includes a link to a list of some of the better online choices for Canada I’m aware of if you are considering an online purchase.
If you let me know your postal code or the city you live in I’d also be happy to let you know about the better options or possibilities I’m aware of in your area.
Phoenix