Restonic Djh Level 4 Review: Cooling Foam for Hot Sleepers

The Restonic Djh Level 4 is built around one clear promise: a cooler night. Its surface is described as 3X cool-to-the-touch, and that cooling story runs through the comfort layer rather than stopping at the cover. Underneath, a foam-encased 5 support zone system works to keep your spine aligned, while the exclusive Q5 Twin Support coil system supplies the deeper push your back and muscles need. If you sleep warm and you want zoned support without giving up a traditional coil feel, the Djh Level 4 is aimed squarely at you.

Our pick

Saatva Classicthe innerspring alternative with zoned lumbar support and a 365-night trial

• 365-night home trial
• Free white-glove delivery and old-mattress removal
• Lifetime warranty
• Three comfort levels, including Luxury Firm for couples

Check today’s Saatva price →

Who is the Restonic Djh Level 4 for?

The Djh Level 4 suits sleepers who overheat at night and want that problem addressed in the material itself, not just in marketing language. Aluminum fiber is infused into the cell structure of the foam, and Restonic pairs it with a double layer of AlumiLast Memory Foam in the comfort layer. The result is a surface positioned to stay cooler and remain comfortable for twice as long as conventional foam. It also suits people who need targeted support: the 5 support zone system is designed for correct spinal alignment, which matters if you wake with a stiff lower back.

It is equally a good match for sleepers who prefer a coil foundation under their comfort layers. The Q5 Twin Support coil system is the load-bearing part of the mattress, delivering support to the back and muscles. If you like the idea of foam cushioning on top of a responsive coil base, rather than an all-foam bed, this is the construction style to consider.

What does the construction actually do?

Three technologies carry the Djh Level 4, and each one has a specific job. The cooling surface works at the top, where your body makes contact. The AlumiLast Memory Foam works in the comfort layer, cushioning pressure while staying cooler than standard memory foam. The Q5 Twin Support coil system works at the base, pushing back against body weight so your spine settles into a neutral line. On top of that, the foam-encased 5 support zone system divides the mattress into regions of differing support, which is how zoned mattresses aim to give hips and shoulders different treatment from the lumbar area.

Aluminum fiber inside the foam cell structure is the detail that separates this from a generic memory foam layer. Rather than relying on a cooling cover alone, the infusion is part of the foam itself, so the cool-to-the-touch quality is built into the material you sink into.

How firm and how cool should you expect it to feel?

Firmness is not published for the Djh Level 4, so the honest buying advice is this: a mattress with a double layer of memory foam in the comfort zone will feel more contouring than a firm innerspring, and zoned coil support underneath keeps that contour from turning into a sag. If you are unsure about firmness, ask the retailer about comfort options before ordering rather than guessing from photos.

On cooling, the claim is specific and repeated: 3X cool-to-the-touch, helping regulate temperature throughout the whole night. Combined with AlumiLast foam rated to last twice as long as conventional foam, the cooling story is about durability of the effect, not a first-week sensation that fades. Sleepers who run hot in summer, or who share a bed with a warmer partner, are the obvious beneficiaries.

Specifications at a glance

Who should buy the Restonic Djh Level 4, and who should look elsewhere?

Buy the Restonic Djh Level 4 if you sleep hot, want zoned spinal support, and prefer foam comfort over a coil base. Its cooling claim is 3X cool-to-the-touch, its comfort layer is a double layer of AlumiLast Memory Foam with aluminum fiber infused into the foam cells, and its support comes from a foam-encased 5 zone system plus the Q5 Twin Support coil system. That combination targets two common complaints at once: temperature and alignment. It is a sensible pick for back sleepers who wake stiff, for warm sleepers in warm climates, and for anyone who has found plain memory foam too slow and too warm. Look elsewhere if you want a fully specified firmness scale, a published trial period, or an all-foam build with no coils, because those details are not part of what Restonic publishes for this model.

What does the Restonic Djh Level 4 cost, and what comes with it?

Ask three questions before you buy: what is the full retail price in your size, is there a home trial, and what does the warranty cover for sagging beyond normal settlement. Those answers vary by retailer, and they matter as much as the foam spec on a mattress you will keep for years.

For a reference point on what a premium innerspring with a full service package looks like, the Saatva Classic lists at $2,229, with a 365-night home trial, free white-glove delivery including old-mattress removal, and a lifetime warranty. That is the level of policy to compare against when you price the Restonic.

Who should not buy the Restonic Djh Level 4?

Skip this model if you need a firm, minimal-contour sleeping surface. A double layer of memory foam will hug you, and sleepers who dislike sink, particularly stomach sleepers who want a flat platform, may find the comfort layer works against them. And if you sleep cool by nature and care more about edge support, motion transfer, or noise than about temperature, those are not the areas Restonic highlights here, so you would be buying on assumptions rather than on stated strengths.

How does it compare with the Saatva Classic?

Both are coil-based mattresses with a comfort layer on top, but they solve different problems. The Djh Level 4 leads with temperature regulation and zoned support through its 5 zone system and AlumiLast foam. The Saatva Classic leads with service and choice: three comfort levels (Plush Soft at 3/10, Luxury Firm at 5 to 7/10, and Firm at 8/10), two mattress heights (11.5 and 14.5 inches), a 3-inch Euro pillow top, and patented Lumbar Zone Technology for spinal alignment. Saatva also publishes CertiPUR-US certified foams, GREENGUARD Gold certification, and endorsement from the American Chiropractic Association.

Buy the Restonic if cooling is your single biggest complaint and you already know the firmness you like. Buy the Saatva if you want to choose firmness, try the bed for a full year, and have it delivered and set up with your old mattress taken away.

What do buyers and the Almanac say?

Public review counts for the Djh Level 4 are not part of what Restonic publishes on its product page, so there is no aggregate rating to quote here. What can be assessed is the construction against the promises: cooling materials, zoned support, and a named coil system are all present, and the durability claim for AlumiLast foam gives the cooling story a time horizon rather than a first-night hook.

World Sleep Almanac score: 7.6/10. The score reflects the strength of the construction claims weighed against the limited published policy information. Our scoring method will be explained in full on a dedicated methodology page.

Frequently asked questions

Is the Restonic Djh Level 4 good for hot sleepers?

It is designed specifically for them. The surface is rated 3X cool-to-the-touch, aluminum fiber is infused into the foam cell structure, and a double layer of AlumiLast Memory Foam sits in the comfort layer. Restonic states the combination helps regulate temperature throughout the whole night, and that the AlumiLast foam stays comfortable twice as long as conventional foam.

What is AlumiLast Memory Foam?

It is Restonic’s memory foam with aluminum fiber infused into the cell structure of the foam. The infusion is what supports the cooler sleep surface claim, and Restonic positions the foam as lasting twice as long as conventional memory foam while remaining comfortable.

How does the 5 support zone system work?

The comfort and support layers are foam-encased and divided into five zones, so different regions of the mattress deliver different levels of support. Restonic’s stated goal for the system is correct spinal alignment, working alongside the Q5 Twin Support coil system beneath it.

Does the Djh Level 4 have coils?

Yes. It uses Restonic’s exclusive Q5 Twin Support coil system, which the brand describes as delivering the support your back and muscles need for optimal sleep. The coils sit under the foam comfort layers rather than replacing them.

Is the Restonic Djh Level 4 firm or soft?

The construction, with a double layer of memory foam over a zoned coil system, suggests a contouring feel rather than a hard one, but confirm firmness options with the retailer before ordering.

Reviewed by the World Sleep Almanac editorial team. Updated 2026.