Sierra Sleep by Ashley
Sierra Sleep Comfort Plus Mattress (M50911)
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The verdict: the Sierra Sleep Comfort Plus is a straightforward medium hybrid for sleepers who want a real coil base doing the support work, with just enough foam on top to quiet pressure points, not a plush pillow top you're paying extra for and won't use.
This is model M509 in the Sierra Sleep line, Ashley's in house mattress brand, and the build follows clear logic from top to bottom. A stain treated, four way stretch cover sits over a layer of high density quilt foam for the initial give, which hands off to a layer of high density gel memory foam positioned specifically under the lumbar area for extra low back support. Below that sits a firming support pad, then the working core: a power packed system of individually wrapped coils, reinforced along the perimeter so the edges hold up under weight instead of collapsing when you sit to put your shoes on. A final support pad anchors the base. Ten inches total, and it ships compressed in a box, so give it roughly 48 hours to fully expand once it's unboxed before you judge the feel.
Feel and support
Ashley calls this a medium feel, and that tracks with how it sits under you: enough give at the shoulder and hip that side sleepers aren't fighting a hard surface, enough push back from the coil system that back and stomach sleepers stay level instead of sinking past neutral. Because the coils are wrapped individually rather than tied together, each one responds to the weight above it on its own, so a partner shifting around or getting up in the night is far less likely to travel across the mattress and wake you. It sits fine on a standard foundation or platform, and it flexes cleanly on an adjustable base if you like to raise your head or your feet.
Who it suits
- Back and stomach sleepers who want even, responsive support without a firm slab feel
- Side sleepers who need a medium cushion rather than a deep plush sink
- Couples who want the wrapped coils' motion isolation on a shared bed
- A guest room, rental, or second home where a dependable, no surprises mattress matters more than chasing a specialty foam feel
Who should look elsewhere
If you already know you want the slow, deep hug of thick memory foam, or a genuinely firm surface with almost no give, this isn't built to be that. The Comfort Plus is aimed squarely at the middle of the range on purpose, not as a compromise but as the point of the design. Sierra Sleep backs it with a 10 year non prorated warranty, and it's built across Twin, Full, Queen, and King, with more coils in the wider sizes to keep support even from edge to edge on a bed two people share.
The only real way to know if medium is your medium is to lie down on it. Stop by any of our Kentucky showrooms and spend a few minutes on the Comfort Plus next to the firmer and softer beds on the same floor, so you're feeling the difference in your own sleep position instead of guessing from a description on a screen.
What makes this mattress different
Medium hybrid, built for the middle
A wrapped coil core under quilt foam and gel memory foam lands squarely in the medium range, support underneath with just enough cushion on top.
Gel memory foam under the lumbar
The high density gel memory foam layer is placed specifically under the lower back, not spread evenly across the whole surface, so it's doing a job rather than just adding thickness.
Reinforced perimeter coils
A ring of firmer wrapped coils runs the edge of the mattress, so the sides hold their shape when you sit down instead of rolling you toward the center.
Wrapped coils cut motion transfer
Each coil moves independently, so a partner rolling over or getting up early is far less likely to send a ripple across to your side of the bed.
Stain treated, four way stretch cover
The cover is built to resist stains and flex with the mattress rather than bunch or wear thin at the seams over normal use.
Works flat or raised
It sits fine on a standard foundation or platform, and flexes cleanly on an adjustable base if you want your head or feet raised.
Compresses and ships in a box
Like most Sierra Sleep mattresses, it arrives compressed and rolled; plan on about 48 hours after unboxing for it to fully expand before judging the feel.
10 year non prorated warranty
Sierra Sleep backs the Comfort Plus with a full 10 year non prorated warranty against manufacturing defects.
A coil core doing the real work, with foam placed where it counts
The Comfort Plus runs six layers from top to bottom. A stain treated, four way stretch cover sits over a layer of high density quilt foam, which gives the surface its initial softness. Below that is a layer of high density gel memory foam, placed under the lumbar area specifically for added low back support rather than spread evenly across the whole pad. A firming support pad transitions into the mattress core: a power packed system of individually wrapped coils, with a reinforced row of coils running the perimeter for edge support, so the sides hold up when you sit on the edge of the bed. A final support pad anchors the coil unit from below.
Ten inches total. Because the coils carry most of the support and the comfort layers stay comparatively thin, the Comfort Plus reads as a true medium hybrid rather than a foam bed with springs added underneath. Sierra Sleep ships it compressed in a box; allow roughly 48 hours after unboxing for it to fully expand.
See the full Sierra Sleep lineup →Built for a wide middle of the road, not the extremes
Back sleepers: the wrapped coil core keeps the hips lifted and the spine level, exactly what a medium hybrid is supposed to do for this position.
Stomach sleepers: the same even support keeps the lower back from arching, without the harder pushback of a firm mattress.
Side sleepers: the quilt foam and gel memory foam layer give the shoulder and hip enough room to settle in without sinking past neutral.
Couples: because the coils are wrapped individually, movement on one side stays mostly on that side, useful if one of you goes to bed later or gets up earlier.
Guest rooms and rentals: a medium feel is the safest bet for a bed other people will sleep on, since it rarely feels wrong to anyone the way a firm or plush extreme can.
Probably not for you if: you specifically want the slow, deep hug of thick memory foam, or a genuinely firm no give surface. The Comfort Plus is built for the middle on purpose, come feel one of our firmer or plusher Sierra Sleep and Ashley models if that's what you're after.
Specifications
| Height | 10 in |
|---|---|
| Feel | Medium |
| Firmness | Medium, a true middle of the road feel (not firm, not plush) |
| Construction | Stain treated 4-way stretch cover over high density quilt foam and high density gel memory foam (targeted at the lumbar), a firming support pad, a power packed individually wrapped coil system with reinforced perimeter coils, and a base support pad. 10 inches total. |
| Motion isolation | Very good. Individually wrapped coils respond independently, so movement on one side of the bed is largely contained and rarely travels across to wake a partner. |
| Warranty | 10 year non prorated warranty against manufacturing defects. |
Frequently asked questions
How firm is the Sierra Sleep Comfort Plus?
It's built and sold as a medium feel. There's enough give in the quilt foam and gel memory foam layers for a side sleeper's shoulder and hip, and enough support from the wrapped coil core that back and stomach sleepers stay level. It sits in the middle of the firmness range on purpose, not as a compromise between a firm and a plush model.
Is this a memory foam mattress or a hybrid?
A hybrid. The comfort layers are high density quilt foam and gel memory foam, but the core doing the actual support work is a power packed system of individually wrapped coils with reinforced coils around the perimeter. If you want an all foam feel, look at another Sierra Sleep model built without a coil core.
How many coils does it have?
The coil count scales with mattress size, since a wider bed needs more coils to support the same weight per square inch. It's a power packed wrapped coil system with a reinforced perimeter row on every size, Twin through King.
Will I feel my partner move around at night?
Less than you would on a mattress without individually wrapped coils. Each coil compresses on its own, so movement on one side of the bed is largely contained to that side instead of traveling across to wake you.
Can I use this on an adjustable base?
Yes. The Comfort Plus flexes cleanly on an adjustable base if you like to raise your head or your feet, and it also sits flat and solid on a standard foundation or platform bed frame if you don't have or want an adjustable base.
The mattress arrives compressed in a box. Is that normal?
Yes, this is how Sierra Sleep ships the Comfort Plus. It compresses and rolls for the box, then expands once you cut it open. Give it about 48 hours after unboxing to reach its full height and feel before you judge it.
What's the warranty on this mattress?
Sierra Sleep backs the Comfort Plus with a 10 year non prorated warranty covering manufacturing defects.
Does Sierra Sleep offer an at-home trial on this mattress?
No. Sierra Sleep beds, including the Comfort Plus, don't come with an at-home trial period. Our Kentucky showrooms are where you try before you buy: lie down on this exact mattress, in your own sleep position, next to the firmer and softer options on the same floor, so the decision is based on how it actually feels rather than a description online.
Can I see this mattress in person near me?
Yes, and with a mattress that's always the better way to decide. Mattress Overstock is a Kentucky owned company that has served the state since 2012, with five showrooms: Lexington, Georgetown, Somerset, London, and Richmond. Come lie on the Comfort Plus in your own sleeping position before you decide. Delivery is free across our Kentucky service area with old mattress haul away, 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.
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