What Is an Isotonic Foam Mattress?

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  • Written By: T. L. Childree
  • Edited By: R. Halprin
  • Last Modified Date: 28 September 2019
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An isotonic foam mattress is made of a special material that gently conforms to body contours for more comfortable sleeping. Isotonic foam may be utilized as part of a complete mattress unit or a separate pad for regular mattresses. This special material contains polyurethane foam combined with other chemicals to increase its density and viscosity. An isotonic foam mattress is pressure sensitive and slowly returns to its original shape when not in use. This mattress was originally used to relieve pain and prevent pressure sores for hospital patients.

An isotonic foam mattress is commonly referred to as a memory foam mattress. This mattress is designed to conform to individual body contours by offering lower resistance to pressure. Isotonic foam is not only utilized for complete mattresses, but can also be purchased as a separate top padding for a conventional coil-spring mattress. The density of the material can help relive pain in pressure points caused by ordinary bedding. Isotonic foam is usually much heavier and more expensive than traditional polyurethane foam.

This specialized mattress is constructed of polyurethane foam combined with certain other chemicals that increase its overall density and viscosity. Isotonic foam often has a slightly sticky feel when used without a fabric covering. The thickness of this material can have a significant effect upon a user’s comfort. Very thin layers of isotonic foam compress too easily and provide little or no cushioning effect. Extremely thick layers are usually too soft for a comfortable sleeping surface.


An isotonic foam mattress is available in both high and low density versions that have different reactions to weight and heat. Isotonic foam density can usually be determined by how quickly the material returns to its normal shape after pressure is applied and released. High-density foam reacts primarily to heat and molds to body contours slowly. A low density isotonic foam mattress is more sensitive to weight and quickly conforms to body contours. Low-density foam tends to have a somewhat shorter lifespan than high density material, but is often more comfortable to sleep on.

This material was originally developed for the U.S. space program in the 1960s. It began to be used commercially in the 1980s for certain hospital applications. Patients confined to a hospital bed for long periods of time experienced less pain and bedsores when lying on an isotonic foam mattress, for example. By the early 1990s, these mattresses began to be sold to the general public as an alternative to traditional coil-spring bedding. Their use has become very widespread in recent years as manufacturing costs have decreased.


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Post 3

@donasmrs-- What was the thickness of your memory foam mattress? I suspect that you just had the wrong thickness. The thickness ranges from eight to twelve inches. Those who want a slightly firmer mattress usually do better with a thinner memory foam mattress such as the ten inch one.

You could also try a memory foam topper on top of a firmer mattress. That would provide additional support as well.

Post 2

@stoneMason-- I have back pain also due to a narrow spine. I tried an isotonic foam mattress as well but unfortunately, it didn't work for me. It actually felt too soft. When I laid on my back, I felt like there wasn't enough support for my lower back.

Post 1

Isotonic foam mattress is amazing. I recently bought one and I hadn't gotten such good sleep in years. I had been using a regular bed before but finally decided to buy something better because my back pain became severe and chronic. I asked my doctor for a recommendation and he recommended this type of mattress.

I wasn't sure if it was right for me though so I went to a mattress store and tried out different types of mattresses. As soon as I tried the isotonic foam mattress, I realized that that's what I need. I could actually feel my back pain disappear while lying on it.

It has been two weeks and my back pain has reduced considerably. I'm also sleeping better, without waking up which is just amazing.

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