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

Written by Lisa Bowman, Writer

Our Testing Process

Here at Sleep Advisor, our Sleep Certified experts use a refined mattress and product testing process to give you unbiased product suggestions… Read our full product review process.

In This Article

Which mattress will come on top? Our testers put the Helix Midnight and the Sleep Number mattress to the test and wrote this in-depth review comparing their features.

»

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?

Comparing Firmness, Support & Feel

Firmness

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.

Support

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.

Feel

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.

• 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.

• 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.