I test a new mattress every few weeks for my job, but the Sleep Number i8 Smart Bed is the one I want to sleep on every night

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As Business Insider's mattress reviewer, I don't get to sleep on the same bed every night. But if I could stick with one bed, I would choose a Sleep Number. Thanks to its high-end service and innovation, Sleep Number is the top name in adjustable air mattresses. This is evident in the i8 mattress, the top adjustable bed pick in our best mattress guide for its adaptability with our evolving sleep needs. 

Design

All Sleep Number beds have 20 mattress firmness options that can be customized on each side of the bed. The i8 innovates on this with the sleep-tracking Sleep Number app and responsive air that adjusts the firmness for consistent comfort as you shift in the night. This feature might sound gimmicky, but it helps me stay asleep.

Your "sleep number" is your preferred firmness level from 5 (softest) to 100 (firmest). My sleep number was 35, but my wife preferred 55. Fortunately, the two sides are individually adjustable, so couples with vastly different preferences can be comfortable.

The Sleep Number i8 Smart Bed uses ballistocardiography, a measure of ballistic forces coming from your heart, to calculate your sleep quality and provide a sleep score. After you track your sleep for several weeks and input your sleep goals, the app offers tips for more productive sleep.

The mattress itself is comprised of six inches of various foam comfort layers that sit above the adjustable air chamber. The mattress cover is a polyester/elastin blend.

Our review of the Sleep Number i8 Smart Bed

Setup

Sleep Number provides three different delivery options. For $150, you'll get basic doorstep delivery. Their premium delivery is $250, which includes setup and inspection. For these delivery options, mattress relocation or removal costs an additional $80. The ultimate delivery option, which will cost you $350, includes all the premium delivery benefits plus mattress removal. Sleep Number uses their own delivery crew for all deliveries. I like that they don't rely on third parties for this service because you know you're getting people who know what they're doing.

This proved true when the delivery people couldn't get the queen bed frame up my tight staircase. They recommended a split king frame, which comes in two pieces. This pushed the delivery date back a month.

The second try was successful. The workers set up the base and mattress in about 45 minutes. Despite the brutal task of carrying the components to my third-floor bedroom, they were professional and helpful. Before they left, they ensured my phone was paired with the bed and showing me how to use the app. I appreciated that I don't need a remote to operate the mattress. The app controls everything, and it was whisper-quiet when I made adjustments.

I also love how few wires the i8 smart bed has. The adjustable base (I tested the FlexFit 2) and mattress are powered by one electrical cord that plugs into your wall. This starkly contrasts with the other adjustable beds I've tested, which leave several wires on the floor and require multiple wall outlets.

Though the bed had a strong new bed smell, the odor dissipated by bedtime.

Comfort

I'm a side sleeper but spend time in every sleeping position. Using the Sleep Number app (available for iOS and Android), you can turn on the "responsive air" function, which automatically adjusts the firmness as you change positions. This gives you consistent comfort and pressure relief. It worked seamlessly and did a good job of facilitating restful, undisturbed sleep.

Finding the right firmness was easy. Sleep Number recommends lying in your preferred sleep position and starting at 100. Then, using the app, slowly decrease the firmness until you're comfortable. Finding my sweet spot took me a few nights of trial and error, but I didn't make additional adjustments.

In the six months my wife and I tested the bed, Sleep Number made several tweaks to the app that have improved the sleep-tracking accuracy. I checked for accuracy by comparing the data to my Garmin Forerunner 945 smartwatch readings and my subjective experience.

Your mattress preferences change over time. When I was 50 pounds heavier, I preferred a firmer mattress. Now, I look for something softer to keep my spine aligned as I sink in less. Or as you age, your comfort preferences change overtime. If this happens and you have a non-adjustable mattress, you either need a new mattress or a mattress topper, or you can live with being uncomfortable. With a Sleep Number, you can just choose a new firmness.

Edge support

Edge support refers to the amount of support you feel while sitting or laying on the edge of the bed. It's especially important for couples, since you're more likely to lay on the edge of the bed when you share it with another person.

I was impressed with the mattress's edge support. I felt comfortable sitting on the side of the bed to put on my socks and shoes and lying on the edge to cuddle my wife in the morning.

Motion isolation

If you share the bed with another person or pet, you'll want a mattress with excellent motion isolation. Good motion isolation helps you sleep without feeling every movement on the mattress.

During testing, I found that the motion isolation of the Sleep Number i8 was subpar. My wife said it felt like a waterbed when I flopped on the mattress.

Heat dissipation

The heat dissipation was poor. When I got up to go to the bathroom at night, the spot where I was sleeping would still be warm when I returned. Hot sleepers may want to consider another option. I'd recommend the Sleep Number Climate360 if you can afford the $10,000 price tag. I was impressed with its built-in heating and cooling capabilities, giving you a custom feel. It's one of the best cooling mattresses I've tested.

Trial period and warranty

Sleep Number mattresses have a 100-night trial. If you try your mattress for at least a month and aren't satisfied, you can return or exchange it within the first 100 days. There is a $250 return and exchange fee, though.

Sleep Number has a 15-year limited warranty. For the first year you own the mattress, Sleep Number is fully responsible for repairs or replacements associated with flaws in workmanship. For the next 14 years, you will be responsible for paying for a portion of replacements or repairs.

Cons to consider

The Sleep Number i8 has poor heat dissipation and motion isolation, so it might not be the best option for someone who sleeps hot or shares the bed with a restless sleeper.

As I tested mattresses on the other side of our "bedsroom," my wife continued to sleep on the i8 for several months. She liked to sprawl out. Unfortunately, the divider between the two air chambers makes sprawling uncomfortable. Also, the sleep tracker didn't recognize when one person was sprawled across both sides of the bed. Consequently, her sleep stats were inaccurate when she did this. For these reasons, I would not recommend Sleep Number beds for people who sleep alone.

The mattress is also hard to move since it is attached to the base. You can try to detach it and move it separately or attempt to move the whole unit. Either way, it's a chore.

What are you alternatives?

At $4,000 for the queen, the Sleep Number i8 is out of the price range of most consumers, but I think it's worth it if you can afford it. Their entry-level model, the C1 Smart Bed hovers right at the value-oriented $1,000 mark, with a slimmer eight-inch profile that is firmer and provides less pressure relief.

If finances are of no concern, you can't beat the Sleep Number Climate360. It's a splurge at around $10,000 for a queen, but it combines temperature control and adjustability for an unparalleled luxurious sleep experience.

Also, within the realm of adjustable mattresses is the Saatva Solaire Adjustable Firmness Mattress, which as 50 different firmness settings and interchangeable foam and latex layers, but it does not offer sleep tracking or utilize an app. Saatva includes free in-home setup with a yearlong trial and lifetime warranty. Our Solaire mattress review covers its excellent heat dissipation and edge support, but like the Sleep Number also had subpar motion isolation.

Dual firmness mattresses are also useful for couples with different sleep preferences, as seen in latex-first options from the likes of PlushBeds Botanical Bliss, one of the best cooling mattresses and the NaturePedic EOS, both of which are organic mattresses that let you customize each side of the bed.

Now, the best mattress we recommend overall is the Leesa Sapira Hybrid. It's a medium-firm hybrid that suits all sleep positions, making it a great option for couples with different sleep needs. It also sleeps cool, has sturdy edge support, and minimal motion transfer. Read our Leesa Sapira review for more information.

The bottom line

If I weren't a mattress tester trying out new beds every two weeks, I would sleep on a Sleep Number Smart Bed every night. Even though I sleep hot and the Sleep Number i8 tends to retain heat, I recommend it because of the responsive air feature that keeps my comfort consistent no matter my position. As a stats person, I like as much sleep tracking info as possible to achieve better, more restful sleep. I strongly recommend the Sleep Number i8 Smart Bed if you can afford it.