Is the Sleep Number i8 worth the buzz? Here's how this smart mattress fared after a week of sleeping on it

Tom's Guide

21-05-2025

I've heard so much praise surrounding the Sleep Number brand for years, so I expected to fall in love with the Sleep Number i8 immediately. After a week of testing, I was amazed by all the customizable bells and whistles, like the under-bed lighting, how I can lift the head of the mattress via an app, examine my daily sleep statistics, and adjust the firmness on both sides of the mattress. Despite all that, I slept restlessly and awoke sweating most nights. It's only been a week (stay tuned for my full review), but here's how my initial thoughts of the Sleep Number i8.
Type: FoamMaterials: ceramic chip gel foam, foam Brand-rated firmness (1-10): adjustable from 5 to 100 Height: 12"Trial period: 100 nightsWarranty: 15 yearsPrice: From $2,379 at Sleep Number
I've tested plenty of mattresses over the years, several of which have performed so strongly that they've made it straight into our guide to the best mattress of the year. However, the Sleep Number i8 is my first smart mattress.
From the moment the mattress was set up in my bedroom on a FlexFit 1 Base, I was intrigued at how I could adjust the firmness level on either side of the mattress and that the mattress could gather information about my sleep experience and store it in an app.
Over the course of 7 days, I played with the customization options and found myself using the adjustable head to watch TV before falling asleep. I learned that the edge support is affected by the Sleep Number Setting (another term for firmness level) and that the mattress's ability to isolate motion is superb, which is good news for restless sleepers and bed sharers.Unfortunately, during this time, I found myself waking up warm, sweaty, and sometimes hot, and moved about in my sleep, something that didn't seem to be reflected in my SleepIQ Score in the app. By the end of the week, I had to make some adjustments to my nightly routine in the hope that my body would adjust to the i8.
The Sleep Number i8 mattress is a luxury buy and one of the brand's more expensive mattresses, though not the most expensive (that would be the i10.. Currently, the Sleep Number i8 is 30% off in the Memorial Day mattress sales. That brings the cost of a queen size to $2,799 from $3,999. As part of this sale, all smart bases are 10% off.
Below are the prices for all sizes of the Sleep Number i8 at full MSRP:
A free white glove delivery service is included in the price. Buyers also receive a 100-night trial, though you can't exchange or return your mattress until after 31 days. Sleep Number will exchange or return your product, however, take note that any new product exchanged is considered a final sale. Not to mention, you'll have to pay an exorbitant $250 return or exchange fee. (A FlexFit base cannot be exchanged or returned.)
Sleep Number offers a 15-year limited warranty, during which customers get one year of full coverage and 14 years of limited warranty. Replacement parts provided during the 14-year limited warranty cost a fee, as does the cost of labor and services. You also get a 10-year stain protection limited warranty.
Sleep Number i8 Mattress: twin from now from $3,399 $2,379 at Sleep NumberThe current 30% off deal is usually rolled out for the biggest sale events of the year, like Black Friday. That makes now an especially good time to snap up the i8, which we rate as one of the best smart mattresses of the year. Purchase comes with free white glove delivery, a 100-night trial, a 15-year limited warranty, and a 10-year stain protection warranty.
Every Sleep Number i8 is delivered for free and includes a white glove set up. This makes sense considering how much set up is actually required for the Sleep Number i8. My delivery service team, two great guys named William and Enrique, had me schedule a time for delivery. On the day of delivery, the drivers kept me well informed of their exact arrival time.
As part of my testing, I received a FlexFit 1 Base, a smart mattress base that is compatible with the i8. I didn't realize that the base could fit inside my bed frame. Thankfully, the delivery team explained this and proceeded to remove the slats and the support beam on my bedframe before fitting the FlexFit 1 Base inside of it.
Although I wanted the base to blend seamlessly with my frame, it was too tight of a fit so the legs had to be adjusted so that they were higher than the frame. This wasn't an issue necessarily, but later, when the mattress was added to the base, it did make my bed much taller than I like. Not to mention, you could see the gray colored FlexFit 1 Base since my king-sized bedding was not large enough to cover the 12-inch-tall mattress and the gray base. At least there were no off-gassing smells with the mattress.
I really appreciated that William and Enrique explained every step of the process, so in case I ever needed to move the mattress, I would know how to disconnect and reconnect it. (Too bad the mattress doesn't have handles!).
After setting the mattress on the base, connecting the two hoses, and locking the mattress in place, the team plugged the bed into an outlet. By this time, I had already downloaded the Sleep Number app. Connecting the mattress to the app took no time at all, and Enrique and William walked me through the settings and adjustments that I could make in the app and on the bed itself.
The nice thing about the Sleep Number i8 is that it records your sleep sessions in the app, allowing me to see exactly what firmness setting I used, how long it took me to fall asleep, and how much of my sleep was restful or restless.
Height: 5' 5"Weight: 175 lbs.Sleep style: Combi (side/stomach/back)Sleep issues: Lower back pain Share a bed: NoOther mattresses reviewed: Bear Elite Hybrid, Helix Dusk Luxe, Saatva Memory Foam Hybrid Mattress, Casper Original and more
On the first night, I put the Sleep Number setting (otherwise known as the firmness setting), at 95 out of 100. This level felt like a 7 out of 10 on the firmness scale, with the top surface still very soft and cloud-like, and yet supportive enough to let me sleep on my stomach and back. According to the app, it took me 18 minutes to fall asleep. I had 8 hours and 17 minutes of restful sleep and 1 hour and 11 minutes of restless sleep. My overall SleepIQ score was 87 out of 100, which upon first look, seemed pretty good considering the highest score is 100 and it was my first night sleeping on the mattress.
Unfortunately, this information did not accurately reflect my experience sleeping on the Sleep Number i8.
For one, I was lying on the bed from 10 p.m. to 12:30 a.m. reading a book. The app was unable to determine that I was not, in fact, asleep and recorded that time period as me having fallen asleep and that I seemed restless. Sleep Number does allow me to adjust my sleep session within seven days, but for the purpose of testing, I didn't change it.
When I tried to fall asleep at 12:30 a.m., I struggled to find a comfortable sleep position for about 30 minutes but eventually fell asleep on my side. At least the app accurately recorded that I got out of bed at 4 a.m. to use the restroom and slept restlessly around 6:30 a.m.
Personally, I didn't feel like I slept well at all that first night. Not only did I seem to move in my sleep and had difficulty finding a position that felt comfortable, but I had to take off my pajamas in the middle of the night because I got so hot. Even when sleeping naked, I was still fairly warm, which is not something that I ever struggle with on the mattress I usually sleep on – a PlushBeds Botanical Bliss Organic Latex Mattress.
I quickly learned that it might take me some time to adjust to the i8 mattress and that even though the mattress recorded everything from my bio signals to my circadian rhythm, the results could be slightly skewed.
I thought perhaps that I slept so restlessly the first night because the Sleep Number setting of 95 out of 100 was too firm for my body, so I changed the firmness level to 85 and kept it at that level for the next six days, hoping my body would grow used to it. To be honest, I didn't notice much difference in the firmness of 95 and 85. The surface still felt supportive and slightly cloud-like.
Unfortunately, I had some issues with the app on my second and third night of sleeping on the mattress. For some reason, on the second night, it only recorded me sleeping for 21 minutes from 4:49-5:19 p.m., even though I slept on the mattress overnight.
Thus, I cannot gather any information related to my sleep performance that night. The same thing happened the next evening. It recorded me sleeping from 8:02 p.m. to 2:07 a.m. even though I fell asleep around 10 p.m. and woke up at 6:00 a.m. Suffice to say, I cannot use my SleepIQ Score or any other information recorded from that night.
Finally, the app worked on my fourth night of sleep, and for the remainder of the week, my sleep scores were 84, 85, 79, and 85. These are fairly good SleepIQ Scores. It also recorded that I was restless for 46, 8, 49, and 21 minutes each night and had about 6 hours and 21 minutes to 8 hours and 22 minutes of restful sleep throughout that time period.
That said, there still seemed to be some disparity in these recordings. For instance, one night the app said it took me 0 minutes to fall asleep, which is impossible.
During this time, I never felt like I was actually sleeping well on the Sleep Number i8 despite what my sleep scores said. Every night, I awoke hot or warm at least once, and some mornings I woke up sweating, which is even rarer than me waking up warm.
On the mattress I usually sleep on, I fall asleep in one spot and wake up in that same position. With the Sleep Number i8, I would find myself on the opposite side of the bed in the morning, or sometimes in the center. Once, I woke up with my feet hanging off the end of the mattress. As much as I like sleeping on my stomach or back, I never could find comfort in those positions and could only fall asleep on my side during these seven days.
I should note that I had the Responsive Air feature on, which is meant to automatically sense me at night and adjust the mattress with air to keep me comfortable. I didn't notice the air feature when I slept, and I don't recall it waking me up. It's also unclear if it actually improved my sleep or not, though I would say it probably didn't.
To be fair, there were some great elements to the mattress that I discovered in that first week. One day, I adjusted the firmness level to 5 and 50 and then 65 to feel the difference. I realized that the higher the firmness level, the better the edge support. I even had a friend get in and out of the bed and change positions, and I surmised that the motion isolation, no matter the firmness level, was phenomenal.
I really enjoyed the auto feature of the underbed lighting, which turned on the lights automatically when I got in and out of bed. This was nice because I usually run to the bathroom once a night. I also found myself using the FlexFit 1 Base some evenings to sit up in bed and watch TV or read a book before going to sleep, which is not something I would normally do.
Because there are so many features of the Sleep Number i8, I can confidently say that it took me seven days to fully understand how the app works and how it records my sleep experiences. Though I didn't mention this above, Sleep Number recorded my biosignals like my heart rate, heart rate variability, and breath rate every night. Although I looked at the biosignal ratings every day, I'm unsure if I can fully trust them to be accurate, considering how my sleep scores didn't accurately reflect my experience sleeping on the bed and/or recorded incorrect times.
I need more than seven days to properly test the Sleep Number i8. In that time, I plan to lower the Sleep Number setting. Perhaps 85 is still too firm and I'll do better sleeping at night with a 60 or 75 out of 100 Sleep Number setting. That would surprise me considering that I prefer medium to medium-firm mattresses. But why not try? Hopefully, this will result in less restless nights, moving in my sleep, and the ability to sleep in all three sleep positions comfortably.
While the motion isolation is impressive and the edge support differs depending on the firmness rating, I'm going to try to figure out a way to sleep on the Sleep Number i8 without sweating or growing warm at night. I've placed my most breathable cotton sheets on the mattress and will utilize two fans and sometimes my air-conditioner. Perhaps, I'll even have to sleep without my comforter and just the sheet. Granted, I don't think these measures should be necessary, but if I'm to sleep on this mattress for the rest of the testing period, then I'd rather not sweat every night in my sleep.
Here's to hoping these adjustments aid in better SleepIQ scores, and the ability to wake up feeling fully rested. Check back for my full review.