Best Mattresses

Eight Mars+ review: A smart mattress cover for your most connected night of sleep


Ashlee spent time as a newspaper reporter, AmeriCorps VISTA and an employee at a healthcare company before she landed at CNET. She loves to eat, write and watch “Golden Girls” (preferably all three at the same time). The first two hobbies help her out as an appliance reviewer. The last one makes her an asset to trivia teams. Ashlee also created the blog,, where she writes about casual dining in Louisville, Kentucky.

Sleep is serious business. If I get less than eight hours, I’ll need a cold brew with coffee ice cubes and an afternoon Diet Coke chaser to function the next day. So I was pumped to test the queen-size Eight Mars+, a $1,399 Wi-Fi-connected mattress with temperature control that tracks how you sleep and connects to other smart home devices. I was eager to see if all this technology could help me get more restful sleep, or at least help me learn why I wake up groggy some mornings.

Eight sells smart mattress sets that include a normal mattress and Sleep Tracker cover, which is what makes Eight mattresses smart. The cover is filled with sensors that track events that happen while you sleep and it records your breathing and heart rates. It connects to a Wi-Fi-enabled hub, and you can access your sleep information through the Eight app (available for iOS and Android). Eight also sells the mattresses and Sleep Tracker separately — the mattresses start at $349, and the Sleep Tracker is $399.

The Mars+ is one of Eight’s smart bedroom sets that include a foam/coil hybrid mattress and the Sleep Tracker. The best feature of the Mars+ is its connections to other smart home devices through its IFTTT channel, which the Sleep Number 360 Smart Bed and Beautyrest SmartMotion Base 3 lack. IFTTT, which stands for “If this then that,” is a free service that lets you create rules for different actions connecting products in the internet of things, apps and more. For example, through IFTTT, you can enable the warming feature of the Mars+ to turn on if your Nest thermostat drops below a certain temperature, or you can have your Philips Hue lights come on when the smart alarm in the Eight app goes off. Plus, Eight has an Amazon Alexa skill, so you can ask your Alexa-enabled smart speaker how you slept the night before, or give a voice command to start heating the mattress.

But the Mars+’s best feature is also its biggest weakness. Without IFTTT and Alexa, the smart mattress cover is just a sleep tracker, and there are wearables like the Fitbit that have similar features for a lot less money. Other downsides include discrepancies in sleep data and the lack of proactive sleep insights from Eight’s app.

The Mars+ is a good option for folks who want to know a little more about how they sleep without being attached to a wearable 24/7. Even though the mattress itself is comfy, you can save yourself some money if you buy the Sleep Tracker cover separately and put it on your own mattress.

Setting up the Mars+

Like other mattresses you’ve seen in internet ads or heard about on your favorite podcast, the Mars+ arrived at my door rolled into a box. Once I hauled it upstairs (you’ll need some help that that — the box is heavy), I unrolled the mattress onto my existing box spring, where it sprang to life and had fully expanded by the time I went to bed that night. (You can buy a foundation for the bed on Eight’s website for $275.)

The mattress cover holds sensors placed in a grid, which makes it a bit thicker than a normal cover. You connect the Eight hub to the mattress cover and plug it in to a wall outlet. Follow the instructions within the app (available for iOS and Android) to connect the mattress cover to your home Wi-Fi network. From there, you indicate which side of the bed you sleep on. If you share a bed, you can identify which side of the bed the other person sleeps on so the mattress tracks that data, too. Then, all you have to do is sleep.

Mars+ tracks info on your slumber

To test the Mars+, I slept on a queen-size version of the mattress for about a month. I also went to bed each night with my Fitbit Charge 2 on my wrist so I could compare my sleep stats from Fitbit and Eight.

As a mattress, the Mars+ was a comfy option for sleeping. It’s made up of three layers of foam and a layer of sleeved coils. This combination made for a firmer bed than my typical pillowtop mattress, but I slept fine despite the change.

The mattress cover can heat in two divided zones, so you can warm up your side of the bed without having to worry about making your loved one sweat. Granted, you could accomplish this with a heated blanket, but it’s nice having this feature built into the cover.

In its role as a sleep tracker, I was mostly happy with the information the performance of the Mars+. Here is what the sensors measure:

The Eight app compiles and analyzes this information to give you a daily sleep score out of 100. A feature called the Sleep Coach walks you through a few highlights of what it detected the previous night. For example, the Sleep Coach told me that I slept last night for 1 hour and 40 minutes less than the average Eight user, but I spent the right amount of time (45 percent) in REM sleep. I could then look at charts of my sleep stages during the night and changes in my heart rate and breathing.

Sometimes, there were differences between the information from Eight and Fitbit, specifically concerning how much sleep each device recorded and the amount of time I spent in each sleep stage. For example, on the same night that the Eight app said I slept for 5 hours and 45 minutes, the Fitbit app said I slept for 9 hours and 4 minutes. In this case, the difference came down to the time it took me to go to sleep. On the night in question, I was in bed browsing through the internet for a couple of hours. The Fitbit app thought I was asleep for much of that period, whereas the Eight app accurately detected that I was still awake. My takeaway from these disparities is that sleep is hard to track, so none of this information should be taken as gospel. Rather, I applied the information more broadly: Both apps showed me that I spend too much time awake in bed before I go to sleep, which cuts into the overall time I spend snoozing.

There were also a couple of instances in which the Eight app said I was in bed longer than I actually was. An Eight rep said the company’s engineers have seen this discrepancy when pets or people other than yourself get on and off the bed, so my dog, Dolly, might have impacted the results. But I only saw this two times in four weeks. The same thing happened when my husband rolled onto my side of the bed when I had to get up earlier than him one morning.

The Eight app also includes helpful sleep tools. For example, the Smart Alarm will go off when you’re in light sleep in a 15- or 30-minute window before your alarm is set to go off. This helped me ease my transition from sleep to waking. There are also short mediation exercises and white noise you can enable for a more restful night.

Eight fits right into the smart home

Eight’s channel on IFTTT sets this smart mattress apart from other smart beds. The existence of the channel makes it easy to make scenarios that involve your bed and other smart devices to automate aspects of going to sleep and waking up. Though there are some automations that are already set up in IFTTT (such as connections between Eight and Philips Hue lights and Nest thermostats), you can build your own with any other service that has its own IFTTT channel. My favorite pairing was when I had the Philips Hue light bulb in bedside lamp turn on when the Eight’s smart alarm went off. It’s hard to hit snooze with a bright light in your eyes.

Eight also has an Amazon Alexa skill. That means you can give voice commands to an Alexa-enabled smart speaker to control your Eight bed. Since the smart mattress cover is mainly used for tracking sleep and not taking any actions, there isn’t a lot Alexa can do with it other than turn the heat on or off. However, it was helpful to ask Alexa how I slept because she would give me a rundown of the previous night’s sleep. It was like an audio version of the Eight app’s Sleep Coach.

Final thoughts

A month with the Eight Mars+ showed me a few things about how I sleep. I toss and turn a lot. I’m awake for a long time before I finally go to sleep. And I hit snooze a lot. The bed itself didn’t make me sleep better, but it gave me a broad understanding of how I sleep, and it’s up to me to change my behaviors.

If you’re interested in a smart bed, the Mars+ is a good pick. It’s not as expensive as other smart mattress setups, it works well with other smart devices you have in your home, and it will teach you about your sleep habits. The bed itself is comfortable, and the heating feature is nice on cold nights. But like any other sleep tracker, it’s best to take the information it gives you about your sleep habits as an overview of your behaviors rather than exact scientific data.

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