Sierra Sleep by Ashley
Sierra Sleep 12 Inch Memory Foam Mattress
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Verdict: if you like the classic memory foam sink, the slow, cradling contour under your shoulders and hips, and you do not want to pay for a plush upgrade you do not need, the Sierra Sleep 12 Inch Memory Foam Mattress gets you there without extra frills.
The Build
This bed is Ashley's Peak 12 Series, model M593, and the construction is straightforward by design. A 2 inch layer of memory foam sits on top, soft enough to let your shoulders and hips settle in rather than push back against them. Underneath is a thick, 10 inch base of firm support foam, the layer doing most of the structural work, keeping the mattress from bottoming out under normal use and helping stop movement on one side of the bed from rolling over to wake up whoever is on the other side. A soft stretch knit cover wraps the whole thing, adding a smooth, breathable surface without changing the feel of the layers underneath.
Like most memory foam beds today, this one ships compressed and rolled in a box for easier delivery into a bedroom or up a stairwell. Once it is unrolled and unwrapped, give it roughly 48 hours to fully expand before you judge the firmness. It will feel a little different on day one than it does once the foam has had time to settle into its true shape.
Feel and Support
Call this a medium feel. There is real give at the surface where memory foam always shows up first, but the deep support foam underneath keeps your spine from sagging out of line, especially through the hips and lower back. Side and back sleepers tend to get along with it well, since both positions benefit from a top layer that lets the shoulder or hip settle in a bit while the base holds the rest of the body level. Combination sleepers who move between their side and back through the night usually find a medium memory foam feel like this one forgiving enough to work across positions.
The mattress is built to pair with an adjustable base if you already own one, or plan to add one. A foundation or box spring is not included and should be bought separately. If you already have a base or foundation from a different brand, it is worth checking compatibility before you buy, since pairing mismatched brands can sometimes affect warranty coverage.
Who It Suits
- Side sleepers who want their shoulders and hips to sink in without losing lower back support
- Back sleepers who want a bit of cushion on top of a stable, supportive base
- Combination sleepers who shift positions and need a feel that works in more than one
- Couples who want less motion transfer when one partner gets in or out of bed
- Anyone furnishing a guest room or starting out who wants a dependable memory foam bed without paying for extra layers
It is probably not the right pick if you sleep strictly on your stomach and want a firmer, more resistant surface throughout, or if you are chasing a deep, slow-motion hug from several inches of soft foam up top. Ashley builds plusher options in the Sierra Sleep lineup for that kind of feel.
Available Sizes
Twin, California King
Foam firmness reads a little different depending on the room temperature and the size and weight of the person on it, so the fairest way to judge a memory foam mattress is still to lie down on the actual bed. Stop by any Mattress Overstock showroom across Kentucky and stretch out on the Peak 12 in your own sleep position before you decide.
What makes this mattress different
2 inch memory foam comfort layer
Softens the surface right where shoulders and hips need it, letting pressure points settle in instead of pushing back against them.
10 inch firm support foam base
Does the structural work underneath, keeping the mattress from bottoming out and holding your spine level through the night.
Soft stretch knit cover
A smooth, breathable surface layer that adds comfort to the touch without changing the medium feel of the foam underneath.
Quieter for two
An all-foam build with no coils absorbs movement, so a partner getting in or out of bed is less likely to wake you.
Adjustable base compatible
Works on a flat platform now, and bends cleanly if you add an adjustable base later.
Ships compressed and rolled
Arrives in a box for easier delivery into tight bedrooms or up a stairwell. Give it about 48 hours to fully expand before judging the feel.
12 inch profile
A standard mattress depth that fits regular sheets and sits well on most bed frames and foundations.
Ashley Peak 12 Series, model M593
A straightforward two-layer foam build from Sierra Sleep, Ashley's mattress line, built to do the basics well.
A simple two-layer foam build that does exactly what it promises
The Peak 12 Series, model M593, keeps its construction short on purpose. On top is 2 inches of memory foam, enough to let your shoulders and hips sink in and relieve pressure without the deep, slow-motion hug of a plush bed. Underneath is a 10 inch base of firm support foam, the layer that carries most of the mattress height and does most of the structural work, keeping the bed from bottoming out and helping stop movement on one side from reaching a partner on the other.
A soft stretch knit cover wraps the two foam layers in a smooth, breathable surface without changing how the mattress feels underneath you. There are no coils in this build, so the support comes entirely from the density of the foam core rather than springs. The mattress arrives compressed and rolled in a box, and needs roughly 48 hours after unboxing to fully expand into its true shape and firmness.
See the full Sierra Sleep lineup →Built for side, back, and combination sleepers
Side sleepers: the memory foam top layer lets your shoulder and hip settle in a little instead of resisting them, which is the setup most side sleepers rest easiest on.
Back sleepers: the firm support foam underneath keeps your lower back from sagging out of line, while the top layer still gives a bit of cushion.
Combination sleepers: a medium memory foam feel like this one tends to work across positions if you shift between your side and back through the night.
Couples sharing a bed: the all-foam build limits motion transfer, so one partner getting up early or turning over is less likely to disturb the other.
First bed, guest room, or budget-conscious buyers: a dependable memory foam mattress without paying for extra comfort layers you may not need.
Probably not for you if: you sleep strictly on your stomach and want a firmer, more resistant surface, or you are looking for a deep, slow-sink plush feel. Sierra Sleep builds plusher options for that.
Specifications
| Height | 12" |
|---|---|
| Feel | Medium |
| Firmness | Medium, noticeable contouring at the surface with firmer support underneath |
| Construction | Stretch knit cover over 2 inches of memory foam and a 10 inch firm support foam base, 12 inches total (Ashley Peak 12 Series, model M593). |
| Motion isolation | All-foam build with no coils, so the thick support foam base absorbs movement and limits how much a partner feels you get in or out of bed. |
| Warranty | 10-year non-prorated warranty |
Frequently asked questions
How firm is the Sierra Sleep 12 Inch Memory Foam Mattress?
It sits at a medium feel. The 2 inch memory foam top layer gives noticeable contouring at the shoulders and hips, while the 10 inch support foam base keeps the rest of the mattress from feeling soft or unstable.
What is inside the mattress?
A soft stretch knit cover over 2 inches of memory foam, sitting on a 10 inch base of firm support foam, for 12 inches total. There are no coils in this build; the support comes from the density of the foam itself.
Who sleeps best on this mattress?
Side and back sleepers tend to do well on it, along with combination sleepers who shift positions through the night. Strict stomach sleepers who want a firmer surface, or anyone chasing a deep plush hug, will likely prefer a different Sierra Sleep model.
Does this mattress work with an adjustable base?
Yes. The all-foam construction is compatible with adjustable bases, so it works whether you already own one or plan to add one later.
Do I need a specific foundation or box spring?
A foundation or box spring is not included and should be purchased separately. If you already own a foundation from a different brand, it is worth checking compatibility first, since pairing mismatched brands can sometimes affect warranty coverage.
How long does it take to expand after unboxing?
Plan on roughly 48 hours. The mattress ships compressed and rolled in a box, and it needs that time to fully expand to its true shape and firmness before you judge the feel.
Is there an at-home trial for this mattress?
No. Sierra Sleep mattresses at Mattress Overstock do not come with an at-home trial. Since there is no trial period on this bed, the best way to know if the feel is right is to lie on it in person, and every Mattress Overstock showroom in Kentucky carries this exact mattress on the floor for you to test in your own sleep position.
What sizes does Mattress Overstock carry for this mattress?
Twin and California King. If you need a different size, ask the floor team about other mattresses in the Sierra Sleep lineup that carry a fuller size run.
Can I see this mattress in person near me?
Yes, and with a mattress that is always the better way to decide. Mattress Overstock is a Kentucky-owned company with showrooms in Lexington, Georgetown, Somerset, London, and Richmond. Come lie on this exact mattress in your own sleeping position, and because everyone on the floor is paid the same no matter which brand you choose, the guidance you get is honest.
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.
