Our Helix Midnight vs. Sleep Number 360® c4 Bed Comparison for 2023

Transparency Disclosure – We may receive a referral fee for products purchased through the links on our site... Read More.

Today we’re comparing the Helix Midnight and the Sleep Number 360® c4, two beds with different constructions that share a surprising number of similarities. The Helix Midnight is an 11.5-inch hybrid that features memory foam and a coil unit, while the Sleep Number is a 9-inch smart air bed with foam and an air support system that offers adjustable firmness and sleep-tracking technology.

While both beds have a slightly firm feel, they suit different types of sleepers. Will you be wooed by the Sleep Number’s smart technology or the classic hybrid construction of the Helix Midnight?

Quick Comparison: Helix Midnight vs. Sleep Number 360 c4

Helix Midnight Product Imagee
Check pricing and availability by clicking the button below
  • Hybrid
  • 6-7/10 firmness
  • 10-year limited warranty
  • LISTHelix Midnight Review
Sleep Number c4 Smart Bed
Check pricing and availability by clicking the button below
  • Smart air bed
  • Adjustable firmness
  • 15-year limited warranty

Who I’d Recommend the Helix Midnight For

  • Hybrid fans – If you love the classic feel of a hybrid, then the Helix Midnight is your best bet with its supportive coil unit and foam comfort layers, featuring pressure-relieving Memory Plus Foam and high-grade poly foam.

  • Average to heavyweight side sleepers – Despite the bed being on the firmer side, sleepers should still experience nice pressure relief from the foam layers. However, lightweight types may not be heavy enough to activate the comfort layers, which could cause pressure build-up.

  • People with back pain – With its slightly firm support and pressure-relieving Memory Plus Foam, the Helix Midnight could be the answer to your prayers if you experience back pain.

Who I’d Recommend the Sleep Number 360® c4 For

  • Couples with different firmness preferences – Full sizes and above offer DualAir™ technology, which allows you to customize the firmness on either side of the bed. This can be configured manually, as well as automatically using the Responsive Air™ feature, which adjusts hourly while you sleep.

  • Technology lovers – Along with adjustable firmness, the Sleep Number offers sleep-tracking technology, via its SleepIQ® app. Pressure sensors in the mattress measure breathing rate, heart rate, and movement to assess the quality of your sleep.

  • Back sleepers – Most back sleepers should be able to find a firmness setting that offers great support and pressure relief, although some heavier people may find themselves sinking too deeply into the thin comfort layer, experiencing discomfort.

Comparing Helix Midnight vs Sleep Number 360® c4: Top Similarities

  • Edge support – Both beds feature reinforced perimeter walls (though the Helix Midnight only has this on lengthwise sides). This helps prevent too much sinkage at the edges, which means couples can spread out and use the full surface area of the bed.
  • Support – If you’re looking for a mattress on the firmer end of the scale, you might suit both these mattresses, which offer great support for many sleepers.
  • Breathable cover – You’ll find a breathable cover on both the Helix Midnight and the Sleep Number 360® c4, which should help keep the surface of the bed cool. The Sleep Number’s cover is also removable for easy cleaning.

Comparing Helix Midnight vs Sleep Number 360® c4: Key Differences

  • Technology – The Helix Midnight is a standard hybrid, while the Sleep Number is a smart bed that offers adjustable firmness and sleep tracking. This is reflected in the higher price point of the Sleep Number.
  • Split mattresses – The Helix Midnight isn’t available in split sizes, so if you’re using an adjustable base, both sides of the bed will rise and lower simultaneously. The Sleep Number 360® c4 is available in Split King, FlexTop King, and FlexTop Cali King. You can raise the head and foot of each side independently with the Split King, and raise the head of each side independently with the FlexTop sizes, provided you have a compatible adjustable base. Sleep Number sells a range of FlexFit™ adjustable smart bases.
  • Motion isolation – The Sleep Number is better at motion isolation than the Helix Midnight, thanks to its dual air chambers, which prevent movement from disturbing the person on the other side of the bed. There was more motion transfer on the Helix Midnight because of its coil unit, which is to be expected from a hybrid.

Comparing Firmness, Support & Feel


Mattress firmness is rated on a scale from 1 to 10, with 10 being super firm. The Helix Midnight is considered medium-firm to slightly firm at a 6-7 out of 10. Meanwhile, the Sleep Number c4 offers 20 levels of adjustable firmness.

The c4 is one of Sleep Number’s firmest offerings due to its relatively thin 3-inch comfort layer, and we think it suits back and stomach sleepers. The Helix Midnight could be great for average to heavyweight side sleepers.

Firmness Scale 1-10


Both beds offer great support for many sleepers. The sturdy individually-wrapped coils on the Helix Midnight help to keep the spine aligned, moving with you as you change positions, while cushioning and additional support are provided by the foam comfort layers.

You can increase and decrease support on the Sleep Number, thanks to the adjustable air chambers, which make it highly versatile. The three-zoned gel-infused poly foam provides contouring support at the head/neck, back, and hips.


Both the Helix Midnight and Sleep Number 360® c4 feature breathable stretchy covers that feel durable. While the Helix Midnight feels quite firm, it features memory foam that offers some contouring, while the firmer transition foam keeps you supported.

The c4 also has a firmer feel, with a gel-infused poly foam and fiberfill comfort layer that provides cushioning without the plush, deep hug that you’d get from a soft all-foam bed.

Comparing Sinkage and Bounce

Both the Helix Midnight and Sleep Number c4 beds offer an element of bounce, which can be useful for combination sleepers, people with limited mobility, and those who prefer a responsive mattress for sex. If bounce is your deciding factor, the Helix Midnight offers a bit more bounce than the Sleep Number thanks to its coil unit.

We think the level of sinkage offered by the Helix Midnight works well for most average-weight sleepers, heavyweight side sleepers, and lightweight stomach sleepers.

Most back and side sleepers should experience decent pressure relief from the 3-inch comfort later. However, some heavier people may find themselves bottoming out, causing misalignment of the spine.

Comparing Motion Transfer

The Sleep Number 360® c4 excels at motion isolation, as it has two separate air chambers in sizes designed for two people. This means that any movement a partner makes on their air chamber shouldn’t make its way over to yours, leaving you sleeping soundly.

As expected, the Helix Midnight isn’t the best at motion isolation due to its coil unit. Although measures have been taken to reduce motion transfer with individually-wrapped coils, we still found ourselves disturbed by a restless person on the other side of the bed. However, as the bed is firmer and features two foam layers, lightweight couples may experience decent motion isolation.

Comparing Cooling

There’s nothing worse than waking up in a sweat, so you’ll be pleased to hear that hybrid mattresses like the Helix Midnight and air mattresses like the Sleep Number naturally sleep cooler than all-foam offerings.

The Helix Midnight has a breathable cover, which can be upgraded to a cooling cover for an additional fee, and a coil unit that promotes airflow. The Sleep Number 360® c4 has an air support system, a breathable cover, and a thin comfort layer with a gel-infused foam, which sleeps cooler than regular foam. However, be aware that exceptionally hot sleepers may still overheat on both these beds.

Comparing Construction (Materials & Quality)

Helix Midnight Construction

The 11.5-inch Helix Midnight starts with a Soft Touch cover that’s breathable, stretchy, and soft to the touch. Hot sleepers can upgrade to a GlaxioTex™ cooling cover for 149 dollars.

layers of helix midnight
  • The comfort layer features Helix’s unique Memory Plus Foam, which is a high-density foam that’s designed to contour the body for comfortable pressure relief.
  • The transition layer is made of high-grade poly foam. This is designed to cradle and contour the body, offering ergonomic support and pressure relief, easing you into the coil unit below.
  • The 8-inch coil unit makes up the support layer. Up to 1,000 (depending on bed size) individually-wrapped steel coils help cradle the body and are designed to limit motion transfer. Thicker gauge coils have been added to the lengthwise sides of the mattress to offer edge support.
  • The base layer is made from DuraDense foam, which is designed to offer support and durability.

Sleep Number 360® c4 Construction

The Sleep Number 360® c4 is a 9-inch smart bed that requires an electrical source within five feet and a wifi connection. The removable cover is made from a breathable, stretchy blend of polyester and polypropylene.

Layers of the Sleep Number 360 c4
  • Quilted to the cover is a 1.5-inch thick layer of fiberfill material, which provides soft cushioning, and a 1.5-inch layer of gel-infused poly foam that offers pressure relief and contouring. This foam has three zones to provide extra support for the head/neck, back, and hips.
  • The support layer is made of an air support system. Twin and Twin XL sizes have one 24-gauge vulcanized rubber air chamber, while Full size and up have two. These chambers inflate or deflate to adjust firmness, with a choice of 20 settings. This is done via a hose and pump system that’s concealed inside the mattress.
  • A high-density foam wall perimeter provides edge support.

Comparing Company Policies & Price

  • Warranty – The Helix Midnight comes with a 10-year limited warranty, while the Sleep Number 360® c4 has a 15-year limited warranty. The Sleep Number warranty covers the full cost of repair in the first year, with the customer having to pay 30 percent of the cost in the second year. This rises each year, ending up at 85 percent in the fifteenth year.
  • Shipping – The Helix Midnight ships for free with bed-in-a-box delivery across the United States. Mandatory premium delivery is required for the Sleep Number, which comes at a cost of 249 dollars, and is available in select areas across the U.S. This includes the removal of your old mattress to another room, installation of your new mattress, and a demo of how to use it. Your old mattress can be taken away and recycled for an additional 49 dollars.
  • Trial Period – You’ll have 100 nights to test out both mattresses.
  • Returns – You can return both mattresses within the 100-night trial period, so long as you’ve slept on them for at least 30 nights. Returns are free for the Helix, but not for the Sleep Number; customers have to bear the cost of return shipping or pay Sleep Number 249 dollars plus tax to collect it.
  • Price – The Sleep Number c4 is the more expensive of these two.
SizeThe Helix Midnight Price (w/o discount)The Sleep Number 360® c4 Price (w/o discount)
Twin XL$949$1,699
Cali King$1,549$2,399
Split KingN/A$2,699
Split Cali KingN/AN/A
FlexTop KingN/A$2,699
FlexTop Cali KingN/A$2,699

Helix Midnight vs. Sleep Number 360® c4 Compared Side-by-Side

FeaturesHelix MidnightSleep Number 360® c4
CoverKnitted Soft Touch CoverPoly-blend cover
MaterialsMemory Plus Foam, poly foam, pocket coils
Fiberfill material, poly foam, and air support system
CoolingBreathable cover, coilsBreathable cover, gel-infused foam
Firmness6-7/1020 firmness options
Motion TransferModerateMinimal
Edge SupportGoodGood
SinkageGentle CradleGentle Cradle
Warranty10 years15-year limited
Trial Period100 nights100 nights
Adjustable Base CompatibleYesYes
ShippingFree within the U.S.249-dollar mandatory white glove delivery in select areas across the U.S.
Made in the USAYesYes
Read Full ReviewHelix Midnight Mattress ReviewN/A
Shop NowHelix Midnight MattressSleep Number 360® c4 Mattress

Final Thoughts

We’ve come to the end of our comparison, and we hope it’s helped you decide if either of these beds should be on your shortlist. We think average-weight sleepers could be comfortable on both beds, as well as most back sleepers, who will likely appreciate the slightly firm support on both.

Couples with differing firmness preferences may prefer the Sleep Number 360® c4, with its customizable dual firmness and good motion isolation. However, as it’s an air bed, this may be unchartered territory for some – traditionalists may find it safer to stick to the Helix Midnight, as it has a conventional feel, and there’s less chance of things going wrong.

Quick Comparison: Helix Midnight vs. Sleep Number 360 c4

Helix Midnight Product Imagee
Check pricing and availability by clicking the button below
  • Hybrid
  • 6-7/10 firmness
  • 10-year limited warranty
  • LISTHelix Midnight Review
Sleep Number c4 Smart Bed
Check pricing and availability by clicking the button below
  • Smart air bed
  • Adjustable firmness
  • 15-year limited warranty
Lisa Bowman
Lisa Bowman

Lisa is a content writer for Sleep Advisor, which combines two of her greatest passions – writing and sleeping. She can also be found writing about fitness, sustainability and vegan food.

Her life revolves around her two rescue dogs (who she shares her bed with) and if she’s not running around after them, she’s likely doing yoga, buying new plants, or enjoying a sunset rum at the beach.

Writing for Sleep Advisor has made her realise she needs a new mattress, stat.

Sleep Advisor