OPEN BAG - NM Cozy 8" Medium Firm Memory Foam Mattress - King

Comfort IQ™ · Scored on what actually matters

NM 8″ Medium Firm Memory Foam Mattress — Performance & Feel

Comfort IQ™ scores eight dimensions 0–10 from National Mattress's in-house testing + construction — the same scale on every model, so two beds compare on what actually matters. Results vary by body type, base, and room temperature.

The NM 8″ Medium Firm Memory Foam Mattress lands in the cradle-without-the-pit sweet spot (Pressure Relief 7.5), with a conforming inch of memory foam over a dense support core. At a true Medium 6/10 it suits the broadest range of sleepers, pairs that cradle with strong durability (8.8) and quiet motion isolation (8.0), and carries the highest value rating in this group (9.4). It is a balanced, do-it-all foam bed that conforms gently while staying supportive and built to last. For couples and all-position sleepers who want a quiet, durable, gently-cradling mattress at an unbeatable value, this is a smart everyday choice.

Performance Scores

In National Mattress's in-house Comfort IQ analysis, the NM 8″ Medium Firm Memory Foam scores: Overall 8.3/10, Cooling 8.0/10, Pressure Relief 7.5/10, Motion Isolation 8.0/10, Edge Support 8.7/10, Responsiveness 9.5/10, Spinal Support 8.4/10, Durability 8.8/10.

Best For

Considerations

How It Performs — The Measured Detail

Feel & Firmness · 6/10 Medium

An inch of conforming memory foam over a dense HD support core gives the NM 8″ a true Medium 6/10 feel — soft enough to fill the lumbar gap and cradle the shoulder, firm enough underneath to stop the hips dropping. The memory layer melts in gently rather than pushing back, so you settle into the surface and stay there.

Cooling 8.0

The NM 8″ sleeps temperature-neutral rather than notably cool — peak surface temperature holds in the 30.2-33.0 °C range, with the rise over baseline in the 8.2-11.0 °C range, right around an average bed. The honest trade-off lives in the build: an all-foam core breathes less than a spring bed, so heat has to leave through the surface. That work falls to the breathable comfort foam and the bamboo cover, which wicks and moves air better than a slick knit. By morning it eases back into the 25.2-29.4 °C range. There's no dedicated gel or phase-change layer, so expect steady, average temperature — fine for most, though a genuinely hot sleeper would want a coil bed.

Pressure Relief 7.5

At a true medium firmness the NM 8″ lands in the sweet spot where most bodies get pressure relief without sinking into a pit — the body settles in around the 1.74-2.76 inch range, a real but controlled cradle. It's deep enough to relieve a side-sleeper's shoulder, shallow enough that back and stomach sleepers stay supported. The inch of conforming memory foam spreads load across the shoulders and hips instead of concentrating it on the heaviest points. Side sleepers and anyone who wakes with hip or shoulder soreness are the natural fit; if you want a firmer, floatier surface, this will feel softer than that.

Motion Isolation 8.0

If you share the bed, this is one of the NM 8″'s quiet strengths — all-foam construction swallows movement before it can travel across the surface, where a spring bed transmits it through the coils. Peak transfer lands in the 1.24-4.53 m/s² range, well under the spring-bed field, with movement settling out in the 0.50-0.71 second range. A restless partner rolling over or getting up for a glass of water barely registers on your side. With no coils to carry vibration, the dense foam core absorbs the jolt right at the source.

Edge Support 8.7

Be honest with yourself about edges if you sit or sleep right at the perimeter. This is an all-foam mattress with no coil reinforcement or edge encasement, so the border softens more under load than a spring-encased bed — edge sinkage measures in the 3.52-5.59 inch range, exactly what an unsupported foam perimeter does. You can sit on the side to tie your shoes, but you'll feel it give and roll slightly toward the floor. Sleepers who use the full width of the mattress edge to edge will find a bit less usable surface than a coil bed offers. For a single sleeper in the middle, none of this matters.

Responsiveness 9.5

Don't buy the NM 8″ for bounce — a memory-foam comfort layer responds slowly on purpose, giving a gentle, melting, sink-in feel rather than a springy push-back. Total bounce travel comes in around the 5.01-9.74 inch range, confirming the slow-recovery character you'd expect from memory foam over a dense core. Recovery is actually quick once load lifts — the surface fully reforms in under 3.55 seconds and is mostly settled in under 1.70 seconds — but it doesn't propel you. That makes it easy to settle into and stay put, though combination sleepers who change position a lot may notice it takes a moment to reshape underneath them. This is a hug, not a trampoline.

Off-Gassing 8.5

New-foam smell is real but brief here, and the reasons are concrete — the off-gassing clears in 12-24 hours, with the initial odor rated Low. The foams are CertiPUR-US certified, independently tested to strict low-VOC limits, so what little odor there is comes from low-emission material, not harsh chemicals. Just as important, this bed is made locally in Ontario and ships within days, rather than sitting compressed in a box for months like an imported bed-in-a-box. Unbox it, crack a window the first night, and any faint scent clears fast. The bamboo cover adds to the clean, low-odor feel.

Sleep Position & Body Weight Fit

The medium feel makes this the broadest-fit bed in the lineup. Side sleepers get cradling for the shoulder and hip; back sleepers get a filled lumbar gap with the firm core stopping the hips from dropping; combination sleepers get a balanced surface. Lighter and average builds settle in comfortably; heavier sleepers still get firm core support underneath. Strict stomach sleepers who want a hard, flat plane may prefer something firmer.

At a Glance

Full construction, per-size dimensions and specs are in the product description above. View 365-night trial details.

Frequently Asked