Sierra Sleep by Ashley
Sierra Sleep Millennium 2.0 Foam 14 Inch Mattress
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If you want the classic memory foam hug, softened at the edges and cooled at the surface, the Millennium 2.0 Foam 14 Inch is Sierra Sleep's answer, and it earns the plush label honestly.
This is the Millennium 2.0 line's 14 inch build, model M312, and the extra height over the entry level foam beds in the Sierra Sleep lineup shows up in the layering. A gel memory foam comfort layer sits on top, doing the real work of contouring to shoulders and hips as you settle in. Underneath, a high density support foam keeps the mattress from bottoming out, so the plush feel on top does not turn into a slow sink to the frame. At the base, a green tea infused foam adds stability and helps the mattress hold its shape through years of nightly use.
Built to Sleep Cool
Memory foam mattresses have a reputation for sleeping warm, and Sierra Sleep addresses it directly here. The cover is a stretch knit fabric woven with temperature regulating material, so it works with the gel infused comfort foam to pull heat away from the surface instead of trapping it. The result is a bed that keeps the plush, cushioned feel people want from memory foam without the overheated nights that used to come with it.
Who It Suits
- Side sleepers who want real cushioning at the shoulder and hip, not just a token top layer
- Combination sleepers who shift positions and want the surface to contour wherever they land
- Back sleepers who prefer a softer, huggable feel over a flatter, firmer surface
- Anyone pairing the mattress with an adjustable base, since the foam construction is built to flex with a base rather than fight it
If you sleep hot no matter what is under you, or if you know you need a firmer surface to keep your spine level, this plush build may not be the right match. Sierra Sleep offers firmer options elsewhere in the lineup, and the showroom team can point you to one built closer to what you need.
The Details That Matter
- 14 inches total height, a deep profile with real support underneath the comfort layers
- Made in the USA
- Backed by a 10 year non prorated warranty
- Ships compressed; allow about 48 hours after unboxing for the mattress to fully expand and reach its final feel
The best way to know if a plush memory foam feel is right for you is to lie on it yourself. Stop by one of our Kentucky showrooms, stretch out on the Millennium 2.0 in your usual sleep position, and see how it feels under your own shoulders and hips before you decide.
What makes this mattress different
Real memory foam contouring
A gel memory foam comfort layer conforms to your shoulders and hips as you settle in, the classic plush hug without a rock hard base underneath it.
High density support you can trust
Beneath the comfort layer, a high density support foam keeps the mattress from bottoming out, so the plush surface stays supportive year after year.
Green tea infused base foam
A green tea infused foam anchors the build, adding stability and helping the mattress hold its shape through nightly use.
Cooling built into the cover
The stretch knit cover is woven with temperature regulating material, working with the gel foam to pull heat off the surface instead of trapping it against you.
A true 14 inch profile
Fourteen inches of total height gives the comfort layers real room to work, a deeper build than the entry level foam beds in the Sierra Sleep lineup.
Adjustable base friendly
The all foam construction is built to flex with an adjustable base, so it works whether you are raising the head to read or the feet to ease pressure.
Made in the USA
Built domestically and backed by a 10 year non prorated warranty, so you are covered for the long haul.
Quiet for shared beds
An all foam build with no coils absorbs movement before it crosses the mattress, so a partner turning over is far less likely to wake you.
Three layers of foam, one cooled cover, built for a plush hug
The Millennium 2.0 Foam 14 Inch starts at the surface with a stretch knit cover woven with temperature regulating material, so the plush feel underneath does not turn into a warm night. Just below that sits a gel memory foam comfort layer, the part that does the actual contouring around your shoulders and hips as you settle into the mattress.
Underneath the comfort layer is a high density support foam. Its job is less glamorous but just as important: it keeps the plush top layer from sinking all the way through to the frame, so the mattress stays supportive instead of bottoming out over time. At the base, a green tea infused foam adds stability and helps the whole 14 inch build hold its shape night after night.
There are no coils in this construction, so the softness comes entirely from how the foam layers are tuned, not from springs. That also means the mattress flexes cleanly with an adjustable base instead of resisting it. The result is a genuinely plush, memory foam feel that is built to last and engineered to sleep cooler than older foam beds.
See the full Sierra Sleep lineup →Made for sleepers who want to sink in, not sit on top
Side sleepers: this is the easiest yes on the list. The gel memory foam layer gives real cushioning at the shoulder and hip, the two pressure points side sleepers feel first on a firmer bed.
Combination sleepers: because the comfort layer contours wherever you land, rolling from your side to your back through the night does not mean fighting the mattress to get comfortable again.
Back sleepers who like a softer surface: if you prefer a huggable, cushioned feel over a flatter and firmer one, the plush comfort layer over a stable support base gives you that without losing support underneath.
Couples and light sleeping partners: the all foam build with no coils absorbs movement before it reaches the other side of the bed, so a partner shifting position or getting up early is unlikely to wake you.
Adjustable base owners: the foam construction is built to flex with a base, so raising the head or the feet works the way it should.
Probably not for you if: you need a firmer, more supportive surface to keep your spine level, or you run hot no matter what is under you and want the airflow of a coil hybrid instead. Sierra Sleep offers firmer builds elsewhere in the lineup, and the showroom team can point you to one that fits better.
Specifications
| Height | 14 in |
|---|---|
| Feel | Plush |
| Firmness | Plush, a soft and cushioned feel |
| Construction | Stretch knit cover over gel memory foam, a high density support foam, and a green tea infused base foam: 14 inches total. |
| Cooling | A gel memory foam comfort layer under a stretch knit cover with temperature regulating material draws heat away from the surface, so the plush feel does not sleep hot the way older foam beds did. |
| Motion isolation | Excellent: the all foam build with no coils absorbs movement before it reaches the other side of the bed, so you will not feel a partner shift positions. |
| Warranty | 10 year non prorated warranty |
Frequently asked questions
How firm is the Millennium 2.0 Foam 14 Inch Mattress?
It is built plush: a soft, cushioned surface that leans into the classic memory foam hug rather than a flatter, firmer feel. The gel memory foam comfort layer does most of that work, while the support foam underneath keeps you from sinking all the way to the base. Like all memory foam, it firms up slightly in a cool room and softens in a warm one.
What is the Millennium 2.0 Foam 14 Inch Mattress made of?
From the top down: a stretch knit cover woven with temperature regulating material, a gel memory foam comfort layer, a high density support foam, and a green tea infused base foam, 14 inches total. It is an all foam build with no coils.
Does this mattress sleep hot?
It is built to sleep cooler than older memory foam. The stretch knit cover is woven with temperature regulating material, and it works with the gel infused comfort foam to pull heat away from the surface. That said, an all foam mattress will still hold a little more warmth than a coil hybrid that breathes; if heat is your single biggest concern, ask the showroom team about a hybrid instead.
Who is this mattress best suited for?
Side sleepers and combination sleepers who want real cushioning at the shoulder and hip, and back sleepers who prefer a softer, huggable feel over a flat, firm surface. If you need firmer support to keep your spine level, this plush build is probably not the one to start with.
Will it work with my adjustable base?
Yes. The all foam construction is built to flex with an adjustable base rather than resist it, so raising the head to read or the feet to ease pressure works the way it should. It also sits flat and stable on a standard platform or foundation if you are not using a base.
How long does it take to expand after unboxing?
This mattress ships compressed, so allow about 48 hours after you unbox it for the foam to fully expand and reach its final feel. It is usable sooner, but give it the full window before judging how it sleeps.
Does this mattress come with an at-home trial?
No. Sierra Sleep mattresses, including this one, do not include an at-home trial or comfort exchange period. The honest way to know if the plush feel is right for you is to lie on this exact mattress at one of our Kentucky showrooms before you buy, in your own sleeping position, for as long as you need.
Can I see this mattress in person near me?
Yes, and with a plush mattress in particular, that is the smart way to decide. Mattress Overstock is a Kentucky owned company with showrooms in Lexington, Georgetown, Somerset, London, and Richmond. Stop in, lie on the Millennium 2.0 in your usual sleep position, and feel the plush layers under your own shoulders and hips before you commit.
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.
