When it comes to wearables and other connected wellness gadgetry, the name of the game this year isn’t steps – it’s stages.
Sleep stages, to be exact. A wave of new devices is now coming to market that track your shuteye, assess the quality of your sleep and make suggestions on what you can do to improve. Some even intervene.
More than a third of us don’t get enough sleep, according to the Centers for Disease Control and Prevention. And the impact of that sleep deprivation on our health and happiness – even our careers – is enough to keep you awake at night. Poor sleep can increase the risk for a multitude of disorders, from diabetes to depression. It impacts our outlook, our stress levels and our decision-making abilities. It even impacts our mortality, according to a recent Rand report. Which helps explain why device makers are coming out with devices that track your sleep patterns.
Understanding how much time we spend in each sleep stage gives us far better insight into the quality of sleep than simply logging how many hours we lay in bed. REM sleep, for example, preps the brain for the day by processing and cataloging yesterday. And deep sleep is instrumental in restoring the body.
I’ve been testing three very different approaches to tracking and improving sleep: the Fitbit Ionic smartwatch ($299), SleepScore’s second-generation bedside sleep monitor, SleepScore Max ($149), and novel headgear called Dreem from French startup Rythm ($499). Two other products – headgear from Philips and a unique wearable from startup Spire – aren’t yet available for testing.
The Ionic estimates sleep stages by tracking heartrate variability, or HRV, the minute variations in timing between each beat of your heart.
SleepScore Max takes a different approach. It sits on the nightstand, deriving sleep stages by monitoring breathing patterns. SleepScore says it limits the device’s range to just under four feet, to avoid accidentally recording your partner’s sleep.
This device also helps guide you to create a better sleep environment by measuring ambient light, sound and temperature, which is a nice touch.
Dreem is clearly the most sophisticated. Built into the headset are four electrodes to measure electroencephalographic activity, or EEG. It also has a sensor to monitor heartrate, HRV and blood-oxygen levels.
Dreem also has bone induction sound, which lets it communicate with you without disturbing your partner. It orchestrates background sound in step with your body to help lull you to sleep.
All three are pretty good at figuring out where you need help, and what steps you can take to improve. Dreem takes it a step further. When you’re in deep sleep, the headgear stimulates so-called slow-wave brain activity to enhance recovery. Fascinating.
How accurate are they?
They’re not bad, actually. And Dreem is likely quite good.
Measuring sleep is an inexact science. The gold standard is for a panel of experts at a sleep clinic to monitor things like EEG, ECG (electrocardiogram) and body temperature. The accuracy of the results are gauged by how closely the experts’ scoring aligns. A 0.8 on the “agreement” scale – called Cohen’s kappa coefficient if you’re scoring at home – is considered clinic-quality accuracy.
Consumer technology has come a long way in the past few years. Early fitness trackers, which extrapolated sleep stages purely from motion detection, scored in the 0.2 range – barely better than random. In pilot studies, Fitbit scored 0.52 and SleepScore scored 0.53, considered to be in the moderate range.
With the richest suite of inputs, I’d expect Dreem to score higher than the others. But I don’t know, because Rythm’s pilot study focused on how well Dreem stimulated slow-wave activity during deep sleep, not sleep-stage accuracy.
In practice, the three apps identified more or less the same sleep stages at more or less the same point. The Ionic and Dreem more closely matched the others’ total sleep time. Sleepscore consistently reported more awake time, so it’s possible that, rather than disagreeing, the devices have different definitions for when sleep starts.
Without a doubt, the Fitbit is the easiest to use. All you have to do is leave it on your wrist. That’s it. The smartwatch automatically detects sleep. Battery life is an impressive four days, so it’s not hard to avoid charging overnight.
It also offers the least advice – not surprising given it’s more of a health-and-fitness utility knife than a sleep-specific device. The biggest drawback of SleepScore Max is that you must fire up the app to start tracking – something I forgot to do with some regularity. An upcoming software update promises to add automatic tracking.
Of course, there’s no getting around manually starting Dreem tracking, given that you have to put it on your head.
Without a doubt, Dreem offers the greatest potential for improving sleep. But at $499, it’s also more expensive than the Ionic and SleepScore Max combined.
And in the end, Dreem’s biggest advantage is also its biggest headache. Rythm clearly took great care to make Dreem as comfortable as possible. But it still took me quite a while to get accustomed to wearing it.
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