A writer for CNET evaluates all the sleep tracking features on the recently released Fitbit Charge 4.
Each morning, the Fitbit app gives you a Sleep Score based on everything from sleep duration to sleep stages, heart rate and variations in blood oxygen levels, aka SPO2.
After a few nights of testing, it’s actually provided some useful data about my sleep habits. For starters, I’ve gotten a passing grade (above a 60) every single night, despite waking up to nurse my little one. The app told me it’s normal to spend up to 45 minutes awake each night, which was comforting. It also gives you advice on how to improve your score, like keeping your bedtime consistent, regardless of how late (or early) it is.
Everyone can see basic information in the app, like how much sleep you get and its quality, but Fitbit Premium subscribers get access to heart rate and blood oxygen data. I didn’t see anything out of the ordinary in my chart, but I can see this feature being extremely helpful for people who suspect they might have a more serious sleep-related condition like sleep apnea. In that case it might be worth the extra $9.99 (£8.99, AU$15.49) a month for a premium account.
There is one foreseeable downside: With all this sleep data I worry that I might become dependent on the Sleep Score to feel energized during the day. That is, a low Sleep Score may subconsciously make me feel tired, even though I felt like I got a good night’s rest.
This scientist compares different devices with a professional EEG. You should include the sleep tracking tests he does in your fitness trackers, he keeps adding more and more devices and comparison studies. [Links at the end]
Data from different videos he’s got:
Fitbit Charge3/4: avg 72% accuracy: detects correctly 56.7% deep sleep, 82% light, 75% REM and 11.86% Awake
Fitbit Charge2: avg 73% accuracy
Fitbit inspire 2: Correct 66.7% deep, 66% light, 64.4% REM, 90.5% Awake
Fitbit Sense: Correct 47.1% deep, 55.2% light, 39.6% REM, 75.4% Awake
Garmin vivosmart 3: 69.7% for deep, light and REM and 73.4% on Awake
Garmin Venu Sq: 55.3% deep, 61.4% light , 47.3% REM and 41.2% Awake
Polar Vantage M: Correct 56% deep, 67.6% light, 49% REM, 67.5% Awake
Oura ring is pretty bad at detecting REM sleep: 75% deep, 66% light, 29% REM, 100% Awake
So seems like Garmin and Fitbit are the best in tracking sleep stages and both are screwing the accuracy of their latest models in favour of smartwatch functionality. Let’s spread these videos and let the big companies that we are NOT gonna accept this!
Knowing all this info, I just bought a Charge 4 😀
Note: you can watch the Charge 4 comparison here, but you’ll need to do your math to adapt the data shown to make each sleep stage match 100% to compare with the rest of the data in this post (I did this math to show you the data of the Charge 4 up there)
https://youtu.be/NYRq4ahPJ2c?t=312
You can watch the Oura ring 2020 comparison here: https://youtu.be/atWcp6FmnbE?t=405
And the 2021 comparison including vs a polysomnography device here: https://youtu.be/WPeKkkeS9Zw?t=461