Finding the right temperature in bed can be tricky. Feeling too hot or cold makes it tough to drop off and can wake you prematurely. Since our mental and physical health depends on sleep, that’s a problem. Eight Sleep has the answer. The Eight Sleep Pod 4 is a temperature-regulating mattress cover that tracks your body as you snooze, with a hub that pumps cooled or warmed water into the cover to help you stay in the land of nod for longer.

When I tested its predecessor, the Eight Sleep Pod 3 (7/10, WIRED Recommends), I was wary of the billionaire biohacking buzz, but it won me over. Aside from the increased comfort, the best sleep trackers all told the same story: My wife and I slept longer and got more deep sleep and REM with the Eight Sleep Pod than without. The Eight Sleep Pod 4 brings some welcome improvements, including greater comfort, quieter operation, and handy tap controls, so you don’t have to reach for your phone at night.

Sadly, better sleep does not come cheap. A Pod 4 Cover and Hub for a queen-size bed costs $2,599, but you must also take a year’s subscription to Autopilot for an extra $199. If you already have a subscription, you can transfer it to a new Pod, but you can no longer buy an Eight Sleep Pod without taking the Autopilot subscription. The UK Super King I tested costs £2,699, with a year of Autopilot at £199. It’s a real investment, but sleeping soundly can be transformative.

Hitting the Hay

The Eight Sleep Pod 4 Cover and Hub come in two large boxes. The mattress cover has rubber tubing inside and a soft, plush, dark material on top. It is elasticized for a snug fit on your mattress, and tubing must be routed from the top to plug into the hub. The hub is about the size of a desktop PC, with a fabric front and a big 8 logo. The hub is the brain of the operation, and it cools or heats water and pumps it around the cover.

Setup with the Pod 4 was similar but much quicker than the Pod 3. You pull the cylinder out the top of the hub and pour water up to the fill line. The priming process has dropped to around 10 minutes from a couple of hours for the previous version. You connect the hub to your Wi-Fi using the mobile app. The Pod 4 cover is much comfier than the Pod 3, and the hub is far quieter. It never broke 30 decibels when measured. It makes a subtle hum, like a white noise sleep sound.

The cover is divided into two distinct sides, so you and your partner can select completely different temperatures, which is great if you sleep hot and your partner tends to feel the cold, or vice versa. You enter personal data and preferences into the app during setup, but the Pod learns and adjusts over time with the Autopilot subscription, which we’ll get into in a moment.

If you woke up feeling chilly with the Pod 3, you had to open the app to adjust the temperature, and it’s not ideal reaching for your phone and having to deal with a screen when you’re trying to sleep. The Pod 4 has a ridged panel on each side near the top of the cover within easy reach, and you can tap twice to reduce or three times to increase the temperature. It’s easy to do when you’re half awake but difficult to do accidentally, and the cover vibrates to let you know you’ve been successful. These new controls are probably my favorite improvement.

There is also a silent alarm function that can gently vibrate the cover to wake you up, though as a light sleeper, I found my partner’s side vibrating would wake me as well. You can also set the cover to heat you up or cool you down to wake you up without disturbing your partner.

Subscription Sleep

The relentless creep of subscription services is annoying, and you may balk at the thought of a sleep subscription, but Autopilot is crucial if you want to get the maximum benefit from your Eight Sleep Pod. The Autopilot system weighs your age, gender, preferred temperature, environmental temperature, and sleep stages to make temperature adjustments on the fly to maximize the quality of your sleep.

It can take a few days for Autopilot to get to grips with your needs, but once it does, you can expect to see improvements in your sleep score. I drop off faster in a cool bed, and get plenty of deep sleep early in the night, but tend to sleep for longer and get more REM if the temperature gradually rises towards morning. The cover tracks temperature (ambient and body), heart rate, heart rate variability (HRV), respiratory rate, and movement. It breaks down your sleep stages in the app to give you a score out of 100.

I tested a lot of sleep trackers and found the Oura Ring 4 (9/10, WIRED Recommends) is the best at accurately tracking my slumber. Eight Sleep weighs latency (the time it takes to fall asleep) and consistency more heavily, generally reports a longer sleep duration, and tends to give me a higher sleep score than the Oura. The cynical among you may suspect it has a vested interest in overestimating sleep, but we’re not talking about a huge disparity. I’m willing to believe a cover with sensors has a harder time determining between lying in bed on the verge of sleep and sleeping.

The data is well presented in the app and very easy to scroll through. I also appreciate the option to edit if you disagree, and you can add tags like “alcohol,” “late meal,” or “sick” to better track how different factors impact your slumber and uncover trends. There’s also a simple thumbs-up or down to report whether you think the data is accurate so you can help it improve over time.

You can also set your bedtime and wake time in the app, and the pod will hit your target temperature before you slip under the covers. It takes a while to turn off in the morning if you don’t set an alarm, which is slightly annoying, though you can always turn it off manually in the app.

Sleep Tight

Getting enough shut-eye in the modern world is a challenge. Insomnia is on the rise. The CDC says 8.4 percent of adults in the US take sleeping pills most days, and many more suffer sleep disturbances each year, often caused by stress. I found sleeping pills left me groggy in the morning. When my insomnia got bad, cognitive behavioral therapy got me back on track. But I’ve tried many different sleep gadgets, natural sleep aids, and routines to catch more Zs. Of all of them, the Eight Sleep Pod 4 is my favorite device.

The data tells a clear story. Both my wife and I sleep better with the Pod 4 than without. I miss it when I sleep elsewhere. When I was feverish recently with Covid, the Pod 4 helped me keep my temperature under control. Being cozy in winter or cool in summer is simply lovely. There’s no doubt the Pod 4 increases your comfort. But it is terribly overpriced, and the subscription (now essential for even basic features) has risen since I tested the previous version. I will not be surprised if it goes up again.

There are cheaper alternatives. The Chilipad Dock Pro Bed Cooling System is $1,614 for a double-sided queen-sized cover, and its Sleep Tracker subscription is optional, but I did not find it as comfortable or effective as the Eight Sleep Pod 4. You could also get the Pod 3 for $300 less at $2,295 for the queen-sized cover. While the Pod 4 is quieter and more comfortable, and brings those touch controls, folks with a Pod 3 will struggle to justify the upgrade and should probably wait for a bigger feature bump. You may also consider checking out our best mattresses or best cooling sheets guides.

You don’t need one if you already sleep well, but if you can afford one, the Eight Sleep Pod 4 Cover and Hub is easy to recommend. The flush among you may even consider stretching for the Pod 4 Ultra, which includes an adjustable base but comes in at an eye-watering $4,599. If you can’t stomach the price or the idea of a sleep subscription in perpetuity, I implore you not to try the Eight Sleep Pod, because once you do, it’s hard to live without.