Final Results: Apple Watch Series 6

Sleep tracking, as a concept, isn't a new thing. Fitbit smartwatches and fitness trackers have been outfitted with the required tech for years. But the feature does bring Apple Watch wearers up to speed with the general public in the popular pursuit of better sleep habits.

To be clear, the sleep-tracking functions are actually coded into the watchOS 7 update that can be installed on any Apple watch dating back to the Series 3. But because of the lengthy battery life needed to power them, the Series 6 is best suited for their use. It has a quick-charging feature that helps you top off the battery before drifting to sleep.

The blood oxygen sensor helps, too. It works together with Apple's Sleep app to shed light on your respiratory health and slumber quality, feeding data to the Apple Health app on your iPhone.

In addition to collecting such data, Apple's Sleep app allows you to set hourly sleep goals and bedtime reminders that help you wind down in the evening, giving you the option to turn off nonessential notifications and dim your display.

Instead of being jolted awake in the morning by a piercing audible alarm, you can set your watch to gently coax you from sleep with a light buzzing on your wrist. Better yet, it doesn't interrupt the slumber of anyone nearby.

After a couple of nights of tracking, I can say the watch did a pretty good job at logging my sleep. It figured out when I went to bed each night and got up each morning. And it even recognized the hour of sleep I missed one Saturday when I crawled out of bed—temporarily—to help my husband get our son ready for an early morning hockey game.

Though CR didn't formally test Apple's sleep-tracking technology—that would require a research-grade sleep lab—the feature made it painfully clear that I was falling significantly short of my 8-hours-a-night sleep goal. And, I guess, just knowing that is a win.

The sleep-tracking app also allows you to put the watch in "do not disturb" mode and temporarily turn off notifications, which I highly recommend doing. Even if you mute the sound, the vibration of a silent alert can be enough to wake many people up in the middle of the night. 

Fitbit's latest smartwatches may offer fewer features than the Apple Watch, but they deliver battery life of three days or longer, which comes in handy when you're tracking sleep.

By contrast, Apple's watches have delivered about 18 hours' worth of battery life. That's enough to get you through the day, but the device is often running on fumes by bedtime, especially if you track your workouts and add a few cellular calls.

And that makes nighttime applications, like sleep tracking, tough to use.

So when are you supposed to charge your watch? That can be tough to figure out if, like me, you're used to just plugging it in at bedtime. Apple says the Series 6's battery will power up in about 90 minutes, so you can quickly top it off right before or after you sleep.

I've been charging my watch in the morning; finding the time to do it at night, when I follow less of a routine, is a little harder. More than once, I've gotten ready for bed only to discover that the battery level had dropped too low to make it through the night.

The new Apple watches don't come with the wall adapter needed to plug them into an outlet—they have just a USB cord. This is part of Apple's new sustainability efforts. As the company points out, lots of people have adapters like those laying around.

But I'm not so sure about that. I get new Apple devices every year for work, but the chargers that come with them rarely make it from one year to the next. And so, they're generally in short supply for me. And if you have an iPhone 11 Pro, your phone's wall USB-C charger won't work with the new watches. 

I normally avoid analyzing Apple's bands. After all, style is subjective. And Apple offers such a wide variety of choices, there's generally something for everyone's taste.

But picking a band is a little more important this time around. A band that rubs you the wrong way could be a nuisance at bedtime. And a poor-fitting band makes the blood oxygen sensor harder to use.

In the past, I've been partial to Apple's Sport Loop bands. They're made of fabric and close with Velcro, giving you the perfect fit.

For the Series 6, I went with one of Apple's new Solo Loops. Made of stretchy silicone that fits more like a bracelet, they're lighter and less bulky than Apple's traditional silicone sport bands. They come in fun colors—and nine different sizes, too.

To get the right fit, you can print out Apple's measuring tool, cut it out, and wrap it around your wrist. That sure beats driving to the store. But be careful.

I measured my wrist at home, then had an Apple Store employee double-check the measurement for me, and still ended up with a loop that was too loose. It felt fine but turned out to be one of the reasons I couldn't get a blood oxygen reading.

So I had to return to the store to get a slightly smaller band. Apple has since updated the online sizing tool. It also has revised its return policy, allowing customers with issues to turn in just the band, not the entire watch, to get a better fit.

The band I have now is very comfortable, and I like the look.

Thanks to a handful of little improvements—notably slightly better heart-rate tracking and step-counting accuracy—Apple's Series 6 model is now our top-rated smartwatch.

But when you look at the numbers, it scores just a hair higher than the budget-oriented Apple Watch SE, last year's Apple Watch Series 5, and a few models made by other companies. 

Beyond the blood oxygen sensor, the big hardware improvement in the Series 6 is the faster charging.

So if you don't feel the need to own the latest and greatest, you might be better off snatching up a Series 5 on clearance. It's the only other model that contains Apple's do-it-yourself electrocardiogram feature.

If you're on a budget, Apple's Series 3 watch is still, technically, an option at the bargain price of $200, but it's a few years old.  

For just $80 more, you can get an SE. That watch has much of the same look as the Series 6 and, Apple says, performs at twice the speed of the Series 3. You also get the same accelerometer, gyroscope, and always-on altimeter found on the Series 6.

And the SE works with Apple's new Family Setup feature and the Fall Detection feature. The Series 3 does not.

But if you have your heart set on a top-of-the-line watch that can handle sleep tracking and give you buckets of wellness-related data, the Series 6 may be what you're looking for.