Gel Memory Foam: The Signature Feature


Sealy Optimum consists of gel-foam mattresses. The signature feature of this brand is gel in each of the layers, or as Sealy says, “Cooling Gel Foam from Top to Bottom.” All of the models are memory foam mattresses except those in the Gel Latex Series.


The 2016 lineup of Optimum mattresses is six models: TruHarmony, Destiny Gold, Radiance Gold, Inspiration Gold, Elation Gold, and the Gel Latex Series. Except for the addition of TruHarmony (called TruHarmony Gold by some retailers) and the dropping of Vibrant, these are updated versions of the previous year’s models.



Top Layer

The “Gold” in the new model names comes from the fusion of Outlast Gold, a phase change material (PCM), into or onto the foam of the 2” top layer. The foam itself is either OptiCool® Gel Memory Foam in the Optimum memory foam mattresses, or OptiCool® Gel Latex in the Gel Latex Series models. The gel infused into the foam is intended to absorb heat and to conduct it through the mattress to where it dissipates.

Meanwhile, PCMs play the role a bit differently. They regulate temperature by changing their physical state at either end of a temperature range. One well-known phase change material is water. When it cools to 32ºF, it releases heat, remaining at 32º until it is all frozen. When ice warms to 32º, it absorbs heat until it is all melted. Then at 212ºF water absorbs heat until it is all evaporated. That is why boiling water never gets hotter when you turn up the heat – it just boils faster. PCMs used in mattresses and clothing have a narrower temperature range, but the principle is the same: absorb heat at the top of the range, release it at the bottom. The limitation of PCM temperature regulation is how much heat can be absorbed and how much can be released in the conditions where they are used.

Support Core

Each of the six Sealy Optimum models has a 7” high support core of what Sealy calls Gel OptiCore™ (except for ultra firm beds, Gel Latex models have the option of OptiCore Plus). This is high-density polyurethane foam infused with gel. As with gel in the other layers of these mattresses, cooling is the advertised benefit. The OptiCore was raised from 6” in the previous version of each mattress.

Middle Layer

The middle layer is in each gel memory foam model except TruHarmony, and in each Gel Latex model except the lowest one. This layer ranges from 1” to 4” high, depending on the model. Sealy’s trade name for this is OptiSense® Gel Memory Foam or OptiSense® Premium Latex. The density of this layer relative to the top layer is not disclosed.

Use of Different Densities

In Tri-Pedic mattresses, and copied by Tempur-Pedic, the top layer of a three-layer memory foam mattress is less dense than the second layer. Therefore it is less sensitive to temperature and more sensitive to pressure. The result is that it is more cushioning when the sleeper first lies down before the foam warms up. This is especially useful when the room air is cool. Also, the lighter memory foam adjusts more quickly when the sleeper moves. Heavier memory foam is slower to adapt, and leaves a repositioned sleeper resting on ridges and hollows until it finally re-forms.

As the memory foam in the second layer begins to warm, it begins to yield, conforming to the shape of the sleeper’s body. This then provides the pressure relief and spinal support for which memory foam is valued.


Customer Response

Whatever the density of the OptiCool Gel Memory Foam is in the top layers of Optimum mattresses, for some reason it does not readily respond to a user’s change of position. After reviewing the statements of over 140 Sealy Optimum customers, Sleep Like the Dead (SLTD) gave Optimum a “D” for Easy to move on, and came to this conclusion: “Optimum tends to give significant resistance to changing positions.” This seems to indicate a memory foam in the top layer which is denser than in many other brands of memory foam mattresses.

The same SLTD review also gives Optimum a “D+” for No Heat Retention. A bar graph shows a greater percentage of Optimum users “reporting sleeping hot” than those of all memory foam mattresses. This is in spite of the top-to-bottom use of gel in these mattresses. Obviously, for some reason, the gel is not working well. This could be related to the ease of movement issue in the previous paragraph. Denser (heavier) memory foam tends to accumulate more heat than lighter foam.

Motivated Changes

Sealy must have taken note of the customer response. In its 2016 revisions of Optimum, it increased the height of the support core by an inch, also raising the height of the mattress. If this is to maintain support while lessening density the top layer, it could help address the ease of movement and heat retention issues. It also began using Outlast Gold, the latest version of the PCM material developed for NASA, for better temperature regulation.

The Gel Effect

As to the gel, Dr. Rick Swartzburg concluded from his studies that gel’s ability to cool is limited to how much heat it can absorb and how much it can conduct away from the sleeping surface. In other words, the colder the gel is to begin with, the more heat it can absorb, thus the more it can cool. Also, effective conduction of heat depends on dissipation at a destination for the heat. In other words, it has to have somewhere to go.

Cooling by Airflow

Conduction is better than absorption in cooling, and airflow is more efficient than gel as a means for dissipation of heat by conduction. Optimum is designed in North Carolina by Sealy engineers. The Cocoon by Sealy actually comes from the Tempur-Sealy headquarters in Lexington, Kentucky, so though it has the Sealy name, it appears to be more a product of Tempur-Pedic. The Cocoon depends on airflow for its cooling, and customer reviews so far seem to indicate that it is a cooler mattress than Optimum.

There is no indication in descriptions of Optimum mattresses that airflow has been engineered into the design. This is in contrast to the Breeze models by Tempur-Pedic, which ventilate the comfort and support layers to facilitate the flow of air through the mattress. The Breeze base layers are also designed to dissipate heat. In other words, air is the Breeze method of cooling.

More Efficient Airflow

Even better at cooling is the Airflow Transfer System, developed for Relief-Mart mattresses. The top layers of the mattress are vertically vented, and channels are cut into the top surface of the base layer to connect the vertical airflow to the side of the mattress, where it can be exchanged with room air.http


It remains to be seen how much effect the latest revisions have had on the performance of Sealy Optimum mattresses, especially ease of movement and heat retention.


Update 2017

In 2017, Sealy discontinued its Optimum line. In January, Tempur-Sealy International announced a major revision of Sealy mattress offerings.[1][2]  Optimum mattresses are still available at retailers on a close-out basis with dwindling inventories.

Optimum mattresses featured Sealy’s OptiCool™ gel-infused memory foam. Also featured was Outlast (a phase change material).  Both of these features were advertised as promoting cooling.

Tempur-Sealy did not specify the reason the Optimum brand was dropped in the restructuring of Sealy’s product offerings, but reviews by Sleep Like The Dead (SLTD)[3] do provide some clues. The results of SLTD’s January 4, 2017 review of Sealy Optimum mattresses, “Based on 140 consumer experiences gathered from 23 sources,” after naming the “Good” points of the brand, listed the “Bad” points as “Durability / longevity no better than fair • questionable support • above-average heat trap potential • may be difficult to move on.” They calculated the rate of owner satisfaction as 76%, less than the overall average for memory foam mattresses in general. The Optimum was graded D+ in three areas:
Durability / longevity – 18% report sagging and loss of support less than 3 years after purchase.
Easy to move on – Resistant to changing position and getting out of bed. SLTD rated it not suitable for sleepers who are weak or ill, disabled, or elderly.
No heat retention – close to 11% of owners reported that their Optimum mattresses “slept hot.”

Apparently, SLTD’s study shows that gel infusion is not as cool as many believe. Reviews of several brands of mattresses with gel memory foam indicate that cooling is more effective when coupled with ventilated air flow through the foam to dissipate heat absorbed by the gel. The same study likewise reveals the limitations of PCMs.

The Optimum line in the Sealy portfolio is being replaced by the Conform Line of memory foam mattresses. The new Sealy portfolio has two other lines, the Response Line (innerspring mattresses) and the Hybrid Line (which will be launched in 2018). Posturepedic has been discontinued as a mattress line. Instead, the new lines have models with Posturepedic Technology, which is extra support in the middle third of the mattress, where most of the sleeper’s body weight lies.

Read our review of the new Sealy Conform Line.



  1. Furniture Today, “Sealy to show new lines, brand architecture” by David Perry (January 13, 2017) –
  2. Furniture World Magazine, “Sealy Mattress Brand Gets Strongest Refresh in 130-Year History” (1/20/2017) –
  3. Sleep Like the Dead, “Sealy Optimum Mattress Review, Ratings and Comparisons” (January 4, 2017) –