Sierra Sleep by Ashley
Sierra Sleep Millennium Cushion Firm Gel Memory Foam Hybrid Mattress
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The Sierra Sleep Millennium Cushion Firm Gel Memory Foam Hybrid Mattress is for sleepers who want a firm, stable foundation with just enough cushioning to take the edge off, not a soft bed that lets you sink in. If plush and medium mattresses have felt too soft under your hips and shoulders, this is the firmer end of the Millennium lineup, built to hold you up rather than hug you down.
The Build
Ashley's Millennium Cushion Firm Hybrid (model M507) wraps a 4-way stretch knit cover around two layers of phase change material designed to pull heat away the moment you lie down. Under that sits two inches of copper-infused gel memory foam for a cooling touch at the surface, followed by three inches of sculpted, body-contouring comfort foam that cushions the shoulders and hips without letting them sink too deep. The support core is a NanoCoil unit, individually wrapped, pocketed coils that flex on their own to follow your body's shape and cut down on motion transfer from a partner shifting beside you. The finished mattress measures about 14 inches from top to bottom, tall enough to sit well on a platform frame, a slatted base, or an adjustable base.
Feel and Support
Cushion firm is a specific, deliberate feel: firmer than a plush or medium mattress, with just enough give at the top to soften pressure points at the shoulders and hips. Lie down and the first impression is stability. The coils and comfort foam keep your spine level rather than letting your midsection drop, the way it can on a softer bed. The copper-infused memory foam layer adds a moment of cushioned contact before you settle onto the firmer support underneath, and the individually wrapped coils keep that support responsive instead of rigid, so the bed reacts to your shape without ever feeling like it is giving out under you.
Who It Suits
- Back and stomach sleepers who need their hips and spine kept level rather than sinking into a soft surface
- Side sleepers who prefer a firmer bed and are not looking for a deep memory foam hug
- Sleepers who run warm and want a firmer feel that still manages heat at the surface
- Couples who want the support of coils along with reduced motion transfer between sides
- Anyone replacing an older, sagging mattress who wants a bed that holds its shape night after night
Sleepers looking for a plush, deep-cushioned feel, or side sleepers who want their shoulder to sink in rather than rest on top, will likely find this mattress firmer than what they are after. Ask our showroom team about the Millennium 2.0 Hybrid, built with a softer comfort system over a similar coil support, as a plusher alternative in the same series.
Specs describe the build, but firmness is personal, and cushion firm means something different under every body. Stop by one of our Kentucky showrooms in Lexington, Georgetown, Somerset, London, or Richmond and lie on the Millennium Cushion Firm Hybrid in your own sleep position before you decide.
What makes this mattress different
Firmer anchor of the Millennium line
Cushion firm sits at the supportive end of Ashley's Millennium hybrid lineup, for sleepers who want a stable base under a modest layer of cushioning rather than a deep sink-in feel.
Two layers of phase change material
A pair of phase change layers sit right under the cover, designed to pull heat away the moment you lie down so a firmer surface doesn't trap warmth.
Copper-infused gel memory foam
Two inches of copper-infused memory foam add a cooling touch at the surface and take the hard edge off before you reach the firmer layers underneath.
Sculpted, body-contouring comfort foam
Three inches of shaped comfort foam cushion the shoulders and hips without letting them sink too deep, keeping the overall feel firm and stable.
NanoCoil pocketed coil support
Individually wrapped, pocketed coils flex on their own to follow your body's shape, add responsive support, and help limit motion transfer from a partner moving beside you.
4-way stretch knit cover
A soft, breathable knit cover stretches in every direction and wraps the comfort layers without restricting how the mattress responds to your weight.
About 14 inches tall
The finished mattress measures roughly 14 inches from top to bottom, tall enough to sit well on a platform frame, a slatted base, or an adjustable base.
Backed by a 10-year, non-prorated warranty
Ashley backs the Millennium Cushion Firm Hybrid with a full 10-year, non-prorated warranty, and it's made in the USA.
A firm, stable base with just enough cushioning up top
The Millennium Cushion Firm Hybrid (Ashley model M507) starts with a 4-way stretch knit cover over two layers of phase change material, designed to pull heat off the surface the moment you lie down. Below that sits two inches of copper-infused gel memory foam for a cooling touch at first contact, then three inches of sculpted, body-contouring comfort foam that cushions the shoulders and hips without letting them sink too far.
The support core is a NanoCoil unit: individually wrapped, pocketed coils that move independently to follow your body's shape while keeping your spine level. That coil layer is what gives this mattress its firm, stable character, the comfort foam softens the surface, but the coils underneath do the real work of holding you up. At about 14 inches tall, the mattress has enough depth for a platform bed, a slatted frame, or an adjustable base.
Looking for a softer feel in the same series? Ask our showroom team about the Millennium 2.0 Hybrid, built with a plusher comfort system over a similar coil support.
See more Sierra Sleep mattresses →Built for sleepers who want firm, stable support
Back sleepers: the coil support and firmer comfort layers keep your hips from dipping and your spine level through the night.
Stomach sleepers: a firm surface is what this position needs most, this bed keeps the midsection from sagging and the lower back from arching.
Firm-leaning side sleepers: if you prefer a firmer bed and don't want a deep memory foam hug, the cushioned top layer still softens contact at the shoulder without going soft everywhere else.
Hot sleepers: the phase change layers and copper-infused foam pull heat away at the surface, so a firmer bed doesn't come with the trapped warmth some all-foam mattresses have.
Couples: individually wrapped coils respond to each sleeper separately and cut down on motion transfer, so a partner shifting or getting up early is less likely to wake you.
Probably not for you if: you want a plush, deep-cushioned feel or your shoulder needs to sink in fully on your side, in which case the Millennium 2.0 Hybrid's softer comfort system is worth a look instead.
Specifications
| Height | 14 in |
|---|---|
| Feel | Cushion Firm |
| Firmness | 7 out of 10 (10 = firmest) |
| Construction | 4-way stretch knit cover over two layers of phase change material, 2 inches of copper-infused gel memory foam, 3 inches of sculpted body-contouring comfort foam, and a NanoCoil individually wrapped pocketed coil support core: about 14 inches total. |
| Cooling | Two layers of phase change material sit under the cover and the memory foam layer is copper-infused, both designed to pull heat away from the surface as you settle in. |
| Motion isolation | Good. Individually wrapped, pocketed coils respond to each side of the bed separately, cutting down on motion transfer from a partner shifting or getting up. |
| Warranty | 10-year, non-prorated warranty |
Frequently asked questions
How firm is the Sierra Sleep Millennium Cushion Firm Hybrid?
It sits at the firmer end of the Millennium hybrid lineup. A copper-infused memory foam layer and sculpted comfort foam soften the very top, but the individually wrapped coils underneath keep the overall feel supportive and stable rather than a deep sink-in bed.
Is this mattress a hybrid or all foam?
It's a hybrid. Gel memory foam and body-contouring comfort foam sit on top of a NanoCoil unit, individually wrapped, pocketed coils that give the base its support and responsiveness.
How tall is this mattress?
About 14 inches from top to bottom, deep enough to sit well on a platform frame, a slatted base, or an adjustable base without looking undersized.
Does this mattress sleep hot?
It's built to manage heat rather than trap it. Two layers of phase change material sit just under the cover, and the memory foam layer is copper-infused, both aimed at pulling warmth away from the surface as you settle in.
Is this a good mattress for side sleepers?
It can work for side sleepers who prefer a firmer feel, but it is not built for a deep shoulder sink-in. Side sleepers who want more cushioning at the shoulder may prefer the Millennium 2.0 Hybrid, which uses a softer comfort system over a similar coil support.
What is the warranty on this mattress?
Ashley backs the Millennium Cushion Firm Hybrid with a 10-year, non-prorated warranty, and the mattress is made in the USA.
Can I use this mattress with an adjustable base?
Yes, it's compatible with adjustable bases. A foundation or base is sold separately.
Does Sierra Sleep offer an at-home trial on this mattress?
No. Sierra Sleep beds, including this one, do not come with an at-home trial period. The way to know how the Millennium Cushion Firm Hybrid feels under your own body is to try it in person at one of our Kentucky showrooms before you buy.
Where can I try this mattress in person?
At any of our Kentucky showrooms: Lexington, Georgetown, Somerset, London, or Richmond. Lying down on the Millennium Cushion Firm Hybrid in your own sleep position is the clearest way to know if this firmness is right for you.
Buy it from people you can actually visit
- Free local delivery To your home across Central & Eastern Kentucky.
- Free setup We place and set up your new bed in the room.
- Free old-mattress haul-away The old one goes out the same day the new one comes in.
Independently owned in Kentucky since 2012. Walk in any day (no appointment) and someone who actually knows the floor will help you find the right fit.
Still deciding?
Try it in person at any Kentucky showroom
Walk into any Mattress Overstock location, lie down, and feel the difference yourself. No appointment, no pressure. Our team has over 100 years of combined mattress experience and we're here to help you find the right fit.
