Summarize this article in one sentence.
Each memory foam mattress lists its density in the product information. High-density foam is defined as above 5 (2.27 kg) and especially 6 lbs. (2.72 kg). This mattress will feel quite firm at first, but it will adapt to your body to relieve pain and pressure points. Lasting about 8-10 years, it’s the best choice for those looking for durability, although it will cost more. Mid-grade foam is defined as 4 to 5 lbs (1.81-2.27 kg). This option should also provide you with a durability of about 8-10 years, and it may be more comfortable and less costly than high-density foam. Low-density foam, normally 2 to 3 lb. (0.91-1.36 kg), will likely feel more comfortable when you lie down, as you’ll sink into the layer. While this foam is less expensive than higher density options, it’s also less durable. You may have to replace it within 4-6 years. The ILD is another important indicator of firmness. Low ILDs will give you a soft and comfortable surface, while highers ILDs create resistance and support for your back. You generally want lower ILDs (10-11) for the top layers and at least one layer with a higher ILD (20-40) to prevent low-back pain. Memory foam is a temperature-sensitive material that softens as it comes in contact with your body heat. This is what gives it the ability to contour to your body, but the foam can also get overly hot at night. Many memory foam mattresses now offer top layers made with different materials to increase ventilation and keep you cool. Gel memory foam increases the air circulation in memory foam, providing a cooler surface. This option also offers increased and more balanced support for your back. This may help relieve chronic back pain. Be aware that the gel memory foam will be cool at first, but it will heat up to match your body temperature over the course of the night. Gel layers may only help you fall asleep. Natural latex foam maintains the same general softness and support as memory foam, but does not have its temperature sensitivity. This will likely prevent you from experiencing the cloud-like feeling that comes from memory foam. However, natural latex will not cause you to “sleep hot,” and it won’t give off any chemical odors. CertiPUR-US is an American-based non-for-profit program that prevents foam from including harmful metals, chemicals, ozone depleters, or dangerous gas emissions. Most mattress companies will advertise that their products have received this certification. While companies from all over the world can be CertiPUR-US-certified, the certification adheres to American standards. These standards are comparable with the European-based Eco-label. The density of latex and memory foam mattresses already inhibits the spread of allergy-causing dust mites. The bamboo cover will supplement this resistance, as bamboo is naturally dust and mildew resistant. Before you decide on a product, check out previous buyers’ experiences to avoid falling into a consumer trap. Reviews will provide you with information about the relationship between the cost and the overall comfort and quality of the mattress.

Summary:
Pick high-density foam for firmness and durability. Choose medium-density foam for a compromise. Go with low-density foam for softness and a lower cost. Check the ILD rating of each layer in the mattress. Look for memory foam mattresses with cooling layers. Choose gel memory foam for a cool surface and good support. Pick natural latex foam to avoid the drawbacks of memory foam. Avoid harmful chemicals by checking for CertiPUR-US certifications. Choose a bamboo cover for hypoallergenic protection. Read online reviews to gauge quality and pricing.