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Tom's Guide
04-06-2025
- Health
- Tom's Guide
Sleep Number i8 mattress review 2025: A smart bed with dual adjustable firmness and integrated sleep tracking
When I started testing mattresses nearly five years ago, I thought the most tech-forward aspects of them were creative cooling gels or new materials that ensured the mattress lasted a long time. I never expected smart mattresses that could record your heart rate or measure how restless you were at night. Finally, I got my chance to experience one of this year's best smart mattresses first hand in the form of the Sleep Number i8. Sleep Number is one of the leading mattress innovators, and has for a long time been offering customers the ability to adjust the firmness level on either side of the mattress. The i8 also has this function, but now users can manage it through an app on their phone. This was one of my favorite aspects of the mattress because it contributed to other things like fantastic motion isolation and the unique ability to adjust the edge support to your needs (for instance, a higher Sleep Number Setting or firmness level results in a more supportive edge). Type: Foam smart mattressMaterials: Foam, air chambers, Firmness: AdjustableHeight: 12"Trial Period: 100 nightsWarranty: 15 years limitedPrice: From $3,399 MSRP at Sleep Number As much as I loved the ability to customize the firmness setting and thought it was interesting that the mattress recorded my sleep and biosignals (such as my heart rate) in an app, I was surprised that it took my body an entire month to get somewhat (but not fully) comfortable sleeping on the king-size version of this mattress. I'm not a "picky" sleeper. I'm a 5'5' woman who weighs 175 lbs. I don't sleep warm or hot and I'm a combination sleeper (I can sleep on my side, back, or stomach), which makes me an ideal mattress reviewer. So I was confused by how much I struggled throughout the testing period. Many mornings I woke up sweating or hot, and sometimes my back ached. Though I don't usually move in my sleep on my normal mattress, most nights I slept restlessly on the Sleep Number i8, waking up often and usually in odd positions. Things improved by the last week, but still not as much as I hoped. I wanted to love the Sleep Number i8, but I can't say it's for me. While couples will appreciate the mattress for the ability to adjust the firmness and edge support on their own sides of the bed, they will have to use very breathable or cooling sheets, light bedding and nightwear, and lower their air-conditioning considerably. Or else upgrade to the Sleep Number ClimateCool which enables you to lower the temperature of the mattress by 15 degrees. Buyers may also have to be okay with sleeping on the mattress for 30 days or more until their body grows more used to it. In terms of the mattress recording sleep stats, upon a closer look I discovered that the results were sometimes skewed, limited, incorrect, or didn't quite match with my experience sleeping on the mattress. I know most people are willing to invest a good chunk of coin in a mattress they like – and I'm all for that. Do I think the price for the Sleep Number i8 is a bit high? Yes, considering that I've slept better on more affordable mattresses with fewer features. I can overlook the pricing, but what concerns me most is how Sleep Number's warranty and return/exchange policy don't make sense considering how expensive this mattresses is. For instance, if you want to return or exchange the Sleep Number i8, you'll be hit with a $250 fee, which is considerably higher than most brands. I know that the Sleep Number brand is beloved by many, and I'm confident that many customers have loved the Sleep Number i8. However, it can't hurt to keep reading and take in a more detailed review, in order to know what to expect from this mattress before you bring it into your home. We rate the Sleep Number i8 as the best value smart bed on the market right now. It comes in 10 different models with sizes ranging from twin to FlexTop California king. Here's the MSRP for every size: 30% off is one of the biggest discounts we see from Sleep Number, and the brand tends to rotate this deal around its smart mattress suite. When it hits the i8 smart bed, you can save up to $2,019.60. Although $3,999 for a queen size sounds expensive, costing more than even the best mattresses you can buy online right now, one must remember this is a complete smart mattress without additional subscription fees. In comparison, the Eight Sleep Pod 4 smart bed ($2,649 for a queen) requires you to purchase an actual mattress separately and pay a subscription fee starting from $17 per month. So, we think you're getting better value for your money with the Sleep Number sleep-tracking, adjustable mattress. Sleep Number offers a 100-night sleep trial, which is standard in the mattress industry. However, more unusually, you can't return or exchange the bed until after 31 days as the brand wants you to take time to get used to the mattress. If you need to exchange it or want to return the mattress, Sleep Number will charge you a pricey $250 fee. Although Sleep Number only offers a 15-year limited warranty, which is a touch on the lower end compared to other brands which offer at least a 20-year warranty or a generous lifetime warranties. This suggests that Sleep Number mattresses could last an average of 15 years. The Sleep Number i8 Smart Mattress is 12 inches tall with an exterior cover that's 99% polyester and 1% elastin. There are three layers inside the mattress – a one-inch base pad, a two-inch support foam layer, and three inches of ceramic chip gel foam, which is foam infused with small ceramic chips of gel designed to release your body heat and contribute to better temperature regulation. All foams in the mattress are CertiPUR-US certified, meaning they have low VOC emissions and are made without formaldehyde, ozone depleters, mercury, heavy metals, lead, and phthalates. The most notable part of the Sleep Number i8 mattress design is a pair of air chambers located below the foam layers that can be inflated or deflated to adjust the bed's firmness. Hoses extend from the bottom of both sides of the mattress and hook to the base. When the bed is plugged in and connected to the Sleep Number app, users can adjust the firmness between 5 and 100, with 5 being the softest and 100 being the firmest. There is also a responsive air function that, when turned on, will automatically adjust the firmness with puffs of air when you change position, ensuring that you remain comfortable and undisturbed. When the air chamber is working, it produces a low, unbothersome sound. Lastly, the mattress is outfitted with sensors that record your sleep from the moment you get in bed. It tracks how long it takes you to fall asleep, the amount of time you're restful or restless through the night, and even when you get out of bed. It also monitors and records your biosignals, including your heart rate, heart rate variability, and respiratory rate. Sleep Number encourages buyers to sleep on the mattress for at least 30 days to let their bodies adjust and grow used to the mattress – and this makes a lot of sense after my month-long testing period. The Sleep Number i8 allows you to adjust the firmness on both sides of the mattress between 5 and 100. As someone who likes to sleep on their back, stomach, and side, I tend to prefer a medium-firm mattress, though I'm not opposed to firm mattresses. After the delivery drivers left, I played with the firmness level. I discovered that when set on a 5, the mattress was super soft, and I sunk too far in for my comfort. It felt like a 4 out of 10 on a firmness scale. I didn't think I could properly sleep on my back or stomach at that setting. On the opposite end, a 100 setting felt quite firm and bouncy, more like an 8 out of 10 on the firmness scale. It was considerably supportive and allowed me to lie on my stomach and back. I started out my testing period at a 95, but I slept quite restlessly and couldn't find a comfortable position on my back or stomach. I decided to go down to an 85 Sleep Number setting, but was surprised that this did not improve my sleep. Though 85 was supportive enough to sleep on my back and stomach, I couldn't fall asleep on this mattress without sleeping on my side. (This was the case throughout the entire testing period.) Not only that, but I would wake up often throughout the night and move quite a bit in my sleep. This is not typical for me, and I wasn't sure if it was because I kept growing warm, hot, and sweaty on the mattress, or if it had more to do with comfort. I used to be a restless sleeper as a kid and teenager, but for the past 12 years, my sleep habits have been consistent – I don't sleep hot, I stay in one place, and I sleep for 8 hours getting up once to go to the bathroom. What surprised me most was that there was an entire week when I'd wake up to soreness along the lower sides of my back. Even when that faded, I didn't feel like my day-to-day body stress or soreness from working out was relieved by sleeping on the mattress. For these reasons, I'd rate the pressure relief a 3 out of 5. Finally, I decided to lower the firmness rating to a 65. I thought perhaps the mattress would be too soft for me, but I was glad to discover that it offered a more medium feel, like a 6 out of 10 on the firmness scale. My sleep started to improve slightly. By that time, I'd figured out that I had to use cotton sheets on the Sleep Number i8 and sleep naked at night with the air-conditioning and two fans on, to alleviate the overheating I had been experiencing. Honestly, I can't tell you if my sleep SleepIQ Score improved because of those changes or because I used a 65 firmness setting. By the last week, I decided to drop the Sleep Number Setting to a 50 and then 45. This change seemed to alleviate the soreness in my back (or perhaps my body had grown used to the bed after 3 weeks) and contributed to a more restful night of sleep. Sure, I would still wake up in different positions on the mattress than I normally would, but at least I wasn't waking up in the middle of the night as often. My SleepIQ Score improved as well, with the highest SleepIQ Score being 92 on the third-to-last day of testing. To get a broad picture, I had my parents jump on the bed and test out the feel of the different firmness settings. They liked the lower firmness settings more than the higher ones, preferring levels between 20 and 60. I also placed a 15lb. dumbbell on the mattress to see how far it would sink. At a 100 firmness setting, the dumbbell dipped half an inch, and one inch at a firmness setting of 5.I have to admit that I struggled to test this mattress for a month. In all my testing experience, it's never taken this long for me to grow used to a mattress, (I think the longest it's ever taken was a week) and that meant a month of poor sleep. I'm sure that if I slept on the Sleep Number i8 for a few more weeks my body would grow more used to it and perhaps by the end of the second month, I'd sleep less restlessly. However, when I think about how I haven't have to do that with any of the other mattresses I've tested, I don't know if it's worth it. Score: 3 out of 5 With so many smart features, it makes sense that Sleep Number offers free white glove delivery with the purchase of a Sleep Number i8. I was sent an email that allowed me to schedule my delivery, and on the day of delivery, my drivers provided me updates on when they would arrive. Sleep Number added a FlexFit 1 Base to my order, so I could test the adjustability features of the mattress. For reference, the FlexFit 1 Base has the capability to lift the head of the mattress so you can sit up in bed and watch TV or read in the evenings. It also provides underbed lighting that can be set on automatic, which means it would turn on and off when I got out and into bed. The base is definitely worth the price. I wasn't aware that I could place the base inside my bedframe, so when the delivery drivers – William and Enrique – arrived, they helped me to remove the support beam and slats inside my bed frame before fitting the base inside. The delivery men were not able to adjust the legs so that it was flush with the frame. Instead, William and Enrique had to lift the legs so that the base sat slightly above it. I didn't realize that this would place the bed at about 2.5 feet high. My regular mattress sits at 22 inches off the ground, so the height adjustment was noticeable. I also didn't like that you could see the grey color of the FlexFit 1 Base, since my king size bedding was not large enough to cover both the mattress and the base. There was no off-gassing smell when Enrique and William removed the wrapping around the mattress and placed it on the frame. The mattress lacks handles, so if you need to move it in the future, this could make things a little tricky. At least the mattress is not that heavy. The delivery team connected the mattress to the base and plugged it in. By then, I'd already downloaded the Sleep Number app and created an account. William and Enrique helped me to connect the mattress to the app and then proceeded to show me how every feature worked. I appreciated how thorough they were in their instructions because the app is a bit overwhelming at first. Their insight allowed me to start testing right away. Upon closer look at the warranty, you receive one year of full coverage, and then after that, you'll be charged for a replacement parts and technical service. While some things are prorated each year of the warranty, you could still end up paying quite a bit if one of the hoses should break or if a sensor stops working, which is always a possibility. Score: 5 out of 5 As briefly mentioned in the design section, the Sleep Number i8 comes with air chambers and sensors that measure your sleep. Both the chambers and the sensors are connected to the Sleep Number app. Overall, the Sleep Number app is intuitively designed and easy to use. Under the Smart Bed tab, you're able to adjust the Sleep Number Setting (firmness level) on either side of the mattress between 5 and 100. While some mattress brands allow you to choose a medium-firm or firm mattress upon ordering, Sleep Number i8 is one of the few smart mattresses that lets you adjust the firmness whenever you wish through the app, making this a standout feature. In the same tab, you can also turn on the Responsive Air function which senses the movement of a sleeper and adjusts the firmness in small increments to keep you asleep. If your Sleep Number i8 is connected to a base, you can adjust the head or feet of the base and set the underbed lighting to on, off, or automatic (turns on when you get out of bed).The Sleep Number i8 monitors your sleep at night with sensors, noting when you get in and out of bed, how restless you are (or are not), and the time it takes for you to fall asleep. This information is recorded in a chart under the Sleep tab on the app. Here, you'll also notice a record of your nightly biosignals – heart rate, breath rate, and heart rate variability – too. Sleep Number takes your biosignals, how often you woke up, how long it took you to fall asleep, and creates a nightly SleepIQ score between 1-100. Next to that score is your 30-day average and all-time best sleep score. This SleepIQ score is meant to encourage sleepers to get a higher score, whether that's by finding a better Sleep Number Setting for a less restless sleep, improving your sleep hygiene, or minimizing stress during the day through exercise or meditation. All this information is recorded in a calendar. Sleep Number also offers suggestions for reducing stress and improving your circadian rhythm for a better night of sleep. Sleep Sessions can be deleted or edited, though there are limits. For instance, you can only delete and edit within four days, and you can only adjust your sleep start and end times one way – a shorter length rather than longer length of time. What I appreciate most about the app is how thorough Sleep Number is in providing an explanation of each reading and how it impacts your sleep. For instance, I was not aware that heart rate variability was important but within the app, Sleep Number explains that a high HRV 'means high energy, good recovery, enhanced cognitive performance, and balance of heart and mind.' Without such descriptions of each of the features, I would have been very confused. I should also add that within the app you can get support from the Sleep Number team and search support articles. Now, the real question remains: how useful are these sleep readings? Overall, I'd say they're interesting and helpful in some ways, but they are not as accurate as you might think. For instance, over the course of a month, there were four times when I thought that the Sleep Number i8 glitched and did not record my full night of sleep, instead recording that I slept for only a handful of hours, even though I know I had seven to eight hours' of sleep that night. This resulted in low SleepIQ scores which then affected my 30-day average. Yes, I could have deleted these nights, but I didn't for the sake of testing. I ended up learning that the app might record your sleep for fewer hours if you end up moving to the other side of the mattress. See – I set up the Sleep Number i8 to only record the right side of the mattress. However, I was sleeping so restlessly and moving so much in my sleep that sometimes I'd wake up the next day on the other side of the mattress, or even diagonally on the bed, covering both the left and right sides of the mattress. This is why the Sleep Number i8 didn't always record me as sleeping a full night on the bed – because its sensors measure each side of the bed separately. There were a few other odd quirks too. The Sleep Number i8 couldn't tell when I was relaxing on my bed and not actually asleep. One evening I was reading a book on the mattress from 10 p.m. to 12:30 a.m. and it noted me as having fallen asleep during that time and sleeping restlessly. Other times, the app recorded that it took me zero minutes to fall asleep which is not accurate. Even when the Sleep Number i8 accurately recorded my sleep, I was a little hesitant to believe the readings. There were times where I felt like I slept quite restlessly for hours, and yet, the app recorded that I was only restless for 30 minutes the entire night. One morning I got up at 5:43 a.m. for a bathroom run and returned to my bed a few minutes later, but the app recorded that as my 'wake up time,' even though I slept until 8:45 a.m. Another night, my SleepIQ Score was 90, which is incredibly high. Such a score surprised me because it took me one and a half hours to fall asleep (which the app recorded accurately) and I was restless much of the night due to growing warm (it recorded my restless time as 38 minutes). Plus, I woke up with a sore back that morning. So, why was my SleepIQ score so high? With all of this in mind, I'm a little skeptical about my nightly biosignal readings too. Unfortunately, I did not have any equipment on hand that allowed me to compare the mattress' recordings of my biosignal readings. All in all, the smart features are interesting, but there were so many instances when they weren't accurate. While they may help some sleepers make certain adjustments, it's best to analyze them thoroughly each day to see what you can and cannot glean from them. Score: 3.5 out of 5 I ordered a king-size Sleep Number i8 and tested it for a month between April and May in Texas. In this time, I used my own judgement and expertise as a mattress tester to review the edge support, temperature regulation, and motion isolation, but I also employed a few standardized tests to provide as much insight into the mattress' performance as possible. A mattress' motion isolation capabilities can determine whether you have an uninterrupted night of sleep, especially if you have a partner, kids, or pets that change positions or jump in and out of bed at night. Thankfully, the Sleep Number i8 excels in motion isolation. Part of this has to do with the fact that the mattress is 'split' (not literally) in half by way of a design that lets you adjust the firmness settings on either side of the mattress. I had a few people test the motion isolation by getting in and out of bed and moving positions, and no matter if the Sleep Number firmness setting was the same or different, I barely felt their movements. To verify my personal experience, I ran a test by placing an empty wine glass in the center of the mattress and dropped a 15-lb. weight 8, 12, and 25 inches away. The wine glass wobbled slightly at 8 inches but stood firm at distances of 12 and 25 inches. It never toppled over. I feel confident in saying that the mattress' motion isolation is one of its best features. Score: 4.5 out of 5 Foam mattresses are not the most breathable mattress type on the market, though I've tested plenty that have been breathable or result in a cool night's sleep. Unfortunately, the Sleep Number i8 mattress was not one such mattress. I don't typically sleep warm or sweat at night, even during Texas' hot summers. Of all the mattresses I've tested (over 25), I've only gotten warm on three mattresses, including the Sleep Number i8. When I first started testing the Sleep Number i8, I'd wake up in the middle of the night either warm, hot, and/or sweating. I quickly realized that I couldn't sleep with pajamas on and that if I didn't want to sweat through my sheets, I'd have to use my most breathable cotton sheets, turn on two fans, and utilize my air-conditioning. On my usual mattress (a PlushBeds Botanical Bliss Organic Latex Mattress), I can sleep under a big comforter with the air-conditioning set at 78 degrees, one fan turned on, while wearing pajamas and sleep comfortably. I can't do that with the Sleep Number i8. I tested the mattress over the course of a month in springtime in Texas when the days and nights fluctuated between cool and warm temperatures. However, I never slept on the mattress when the temperature inside my house was over 78 degrees. I attribute a lot of my restless sleep and waking up often in the middle of the night to the poor breathability and heat retention of this mattress. Score: 3 out of 5 Edge support impacts a mattress in more ways than one. A supportive edge guarantees you can get in and out of bed easily or sit on the side of the bed and get dressed. It also contributes to the mattress' overall stability and long-term life span. For most mattresses, it's easy to provide feedback on edge support, but things are a bit different with the Sleep Number i8. This mattress does not have reinforced edges around the perimeter, so the edge support is entirely dependent on the firmness setting you choose. A lower firmness setting results in poorer edge support. The higher the firmness setting, the more supportive the edge. I tested this out by setting the firmness on one side of the mattress at 5 and the other side of the mattress at 100. The side with the 100 firmness setting was incredibly supportive. I barely sunk down, so much so that my feet couldn't lie flat on the ground. Not only that, but when I placed a 15lb. weight on the edge, it only dipped half an inch. The opposite was true on the other side of the mattress. When I sat on the side with a 5 firmness level, I nearly sunk to the base, and actually had to set my feet firmly flat on the ground to prevent myself from slipping off. The 15-lb. weight dipped a full inch on that side of the mattress. I should mention that the results were the same at the foot of the bed as they were on the side of the mattress. Unfortunately, I cannot say the same about the corners of the mattress. No matter the firmness level on that side of the bed, the corners of the mattress dipped considerably, and I had to take care not to slip and fall. If you have difficulty getting in and out of bed, you should probably increase the firmness setting on your side of the mattress before moving off or on the mattress. This can be a hassle, but it's the only workaround I can imagine. Score: 3 out of 5 When I examined the Sleep Number i8 customer reviews, I was impressed. It has a 4.8 out of 5-star rating with over 61,900 reviews. However, the number of reviews made me pause. The Sleep Number i8 launched in 2023. Could there possibly be 61,900 reviews written in less than two years? After a little digging, I realized that the reviews on the Sleep Number i8 page go back 11 years, when Sleep Number first launched an i8 model in 2009. That first model had a lot of similarities in terms of air chambers and the ability to adjust the firmness setting. However, the materials in that mattress differed, as did the set up. Furthermore, the first i8 model was not a smart bed. If all that wasn't enough, I'm not even positive that all the reviews on the page are for i8 models. When searching through them, I noticed that some reviews were in relation to other mattress types like the Sleep Number Flex Top ILE 360 and the Climate360. This skews the star rating, too. The reviews cannot be broken down by years or mattress types so I can't provide a more accurate star rating for the Sleep Number i8 Smart Mattress that I tested in April-May 2025. That's not to say that a 4.8-star rating from 10 years' worth of reviews is not impressive – it is. Only that I would prefer a more accurate star rating for the model that I'm reviewing which has only been out since 2023. While you can't search through the reviews by keyword, you can break them down by the most recent reviews, by star ratings (1-5), the lowest to highest star rating, and the highest to lowest star rating. In looking through the lower star ratings, it's clear that a lot of the complaints center around air valves, warranty, and discomfort leading to pain. (Again, I can't tell if all these reviews are for the Sleep Number i8 Smart Mattress, though I tried to limit my search to the past two years to ensure a higher probability of that). Among the lower star ratings, customers noted that the air valves became faulty causing the mattress to lose air. Typically, this occurred after their one-year full warranty coverage ended. They were not enthused by the high costs for technicians and replacement parts under the 14-year limited warranty. Quite a few pointed out the cost to exchange or refund the mattress. Others shared that the mattress, no matter the firmness, caused them to wake up in pain. That said, there are plenty of reviews praising the mattress for its comfort and ability to adjust the firmness level on either side, resulting in a better night's sleep. Many point out the benefit of buying a base with the mattress, such as how a base can elevate their head at night, resulting in a better sleep. Again – I can't be entirely positive that all the praise or complaints are in relation to the Sleep Number i8 since I found plenty of reviews on the i8 page where customers notated that they were sharing feedback for a different mattress. The Sleep Number i8 is a big investment, so it's important to know what to expect before you buy. Like me, you might be drawn to the smart features and the ability to adjust the firmness levels on both sides of the mattress. I can say without a doubt that being able to adjust the firmness setting is a big pro. It allows couples to sleep more comfortably and find the sleep setting that works for them. No wonder the mattress' motion isolation capabilities are among the best on the market. Plus, you have control over the edge support. The firmer the mattress, the more supportive the edge. Managing the firmness level goes hand-in-hand with the Sleep Number app, which records everything from how quickly you fall asleep to how restfully (or restlessly) you sleep. It even records your biosignals. While this is quite a cool feature, it's not as accurate as you might think. I received skewed results, as well as some that were limited, inaccurate, or didn't match my personal experience sleeping on the mattress. Perhaps the biggest drawbacks to this mattress were the comfort and temperature regulation. It took me nearly a month to figure out that a softer firmness setting would benefit me more, even though I usually sleep better on firmer mattresses. I was also limited to sleeping on my side and even suffered some back pain. This isn't to say that you shouldn't buy the mattress, only that you should be prepared for about a 30-day adjustment period (which for me was not enjoyable but may be less severe for you). As someone who doesn't sleep hot or warm, I often woke up sweaty or hot on this mattress and it affected my sleep most nights. I had to make big adjustments that I haven't had to make with other mattresses like cooling sheets, no sleepwear, two fans, and lowering the air-conditioning considerably. If you don't have A/C or typically sleep hot, you might consider Sleep Number's other smart mattresses, like the ClimateCool and Climat360, which let you control the temperature. If you decide to move forward with the Sleep Number i8, be mindful that the warranty and return/exchange policy are not the greatest. The 15-year limited warranty is lower than most warranties and you'll have to pay for parts and technical service after one year. Sadly, there's a $250 return/exchange fee too. This mattress has a lot of attractive qualities, but it doesn't hurt to look through the Sleep Number catalogue to make sure you're investing in the right option for you. While the i8 lacks temperature regulation, the Eight Sleep Pod 4 smart mattress cover is a great smart bed alternative to the Sleep Number i8 for hot sleepers. Built with an active water-based climate control system, it helps keep you cool through the night while tracking your sleep metrics with in-bed sensors similar to Sleep Number's. At $2,649 for a queen size, it's cheaper than the i8, but you will have to budget for a separate mattress and subscription fee. From the brand behind our #1 bed of the year, the Saatva Classic mattress, the Saatva Solaire adjustable firmness mattress is a high-end luxury alternative to the i8. It's built with natural latex and organic cotton and has 50 firmness options, and it's great for less tech-savvy sleepers who want to control their bed from a remote control rather than a mobile app and aren't bothered about tracking their slumber. At $4,599 for a queen size at MSRP it's an investment purchase, but regular Saatva mattress sales tend to knock between $300 and $500 off. To help you decide which one to buy, check out our Saatva vs Sleep Number mattress head-to-head. Like the Sleep Number and Saatva beds, the Bryte Balance Signature comes with adjustable firmness levels, allowing you to customize the feel of your side of the bed. What's more, it's lined with sleep tracking sensors and an immersive relaxation feature. This means head-to-toe in-bed motion to help you relax at bedtime. Unfortunately, there's not always money off at Bryte, so a queen tends to stand at MSRP of $3,999, but we think that's good value for a smart mattress of this quality — you'd pay a lot more for a nightly massage.
Tom's Guide
21-05-2025
- Health
- Tom's Guide
Is the Sleep Number i8 worth the buzz? Here's how this smart mattress fared after a week of sleeping on it
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 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 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.
