Fitbit is one of the most highly regarded wearables brands in the world, and its trackers do a truly useful service. You can draw upon data gathered by a Fitbit device to gauge your health and well-being, as well as monitor your sleep.
Essential reading: Ten gadgets for advanced sleep monitoring
On the latter topic, people usually wonder… how exactly does a gadget on my wrist track sleep? How accurate is this information?
If you’ve been looking for an answer to these and other similar questions, we are here to help. Read on for everything you need to know on how Fitbit tracks your sleep and how to ensure you get the most accurate readings.
Understanding how Fitbit tracks your sleep
The San Francisco wearables manufacturer now offers quite a few different devices. But when it comes to sleep tracking, some are better than others. Depending on your model, sleep tracking will differ; some models keep tabs on sleep cycles automatically while others require additional user input.
Manual sleep tracking (One, Zip)
If you own a Fitbit One, then your device uses manual sleep tracking. Once you are in bed and ready to go to asleep, press and hold the tracker’s button for several seconds. You will see a stopwatch begin to count, and the other tracker icons will blink, indicating that you are in sleep mode. When you wake up, hold the button down for several seconds to stop the sleep recording. Your tracker’s icons will stop blinking, indicating that you’ve exited sleep mode.
A Fitbit Zip doesn’t track sleep. This means that you need to manually enter this information if you want it to show in your timeline. This is done by manually typing the information on time spent in bed through the website dashboard.
Automatic sleep tracking (Alta series, Blaze, Charge series, Flex series, Inspire series, Surge, Ionic, Versa series)
Those using the models listed above will be happy to know that sleep tracking is automatic. This means you don’t have to fiddle around with statistics nor worry about launching sleep mode when you go to bed. Although you can still do so if you suspect the automatic readings aren’t precise enough. Using manual mode provides you with one additional stat (time to fall asleep), but otherwise manual and automatic sleep metrics are the same.
By default, the device itself will automatically determine when you lie down based on the decreased rate of motion from the accelerometer. For models with a built-in heart rate sensor, the tracker will also factor in your heart rate data into this equation.
When your Fitbit syncs in the morning you’ll see last night’s sleep stats on your dashboard.
The limitations of sleep tracking
Even though Fitbit is a brilliant gadget and really useful as a health tool, it does have certain limitations. For example, it won’t automatically keep track of naps shorter than one hour, since that’s the default resting period that will activate the automated readings. If you’re adept of short naps and you want to capture all your sleep stats, you will have to remember to activate sleep mode manually whenever you lie down.
Sleep stages and more
For a long time, Fitbit devices had no way of detecting sleep cycles. They only gathered info on how long you slept, how many times you woke up and the number of times you were restless. There is a “sensitive” setting which causes your tracker to record nearly all movements as time spent restless or awake. The “normal” setting counts significant movements as being awake (such as rolling over).
A firmware update a couple of years ago brought the much anticipated sleep stages feature to a number of models. All fitness trackers with heart rate sensors apart from Charge HR and Surge are now able to tell you how much Light, Deep and REM sleep you are getting each night. The values are calculated by combining accelerometer data, heart rate variability (the time between beats), and Fitbit’s proprietary algorithms.
Some models also feature a silent alarm function which does a fairly good job of waking you up by vibrating at a set time. Having said that, if you are a heavy sleeper, its probably not a good idea just to rely on a vibrating alarm.
Essential reading: Ten gadgets for advanced sleep monitoring
There are other useful features, too. One of these are personalized sleep goals based on your sleep data which are there to help you achieve your optimal amount of sleep each night. This includes customized bedtime and wakeup targets to establish sleep consistency; reminders to stay on schedule, and a sleep schedule history to chart your progress.
Finally, lets not forget the Sleep Insights feature. This is essentially advice on ways to improve your sleep. Fitbit is using all your activity and diet statistics to discover trends and then dish up personalized guidance on how to improve sleep. The more you wear your tracker to bed, the more personalized insights you may receive.
Even more advanced features and measuring oxygen levels
A number of Fitbit devices have a built-in SpO2 sensor. This includes the Charge 3, Versa and Ionic. Owners of these have patiently been waiting for the tech to be put to real-world use. This has started rollling out earlier this year. The sensor measure oxygen levels in the blood, providing information on how well the body distributes the gas from the lungs to all of its cells.
These levels fluctuate throughout the day. Healthy individuals typically register readings above 97%. Measurements should never fall below 95%, although levels above 92% are generally considered safe.
Fitbit does not provide the actual value, but in the morning you’ll notice a graph called Estimated Oxygen Variation in the sleep section. If the line is green your blood oxygen is fine, orange indicates there may be a problem. There are also two horizontal lines which show the healthy range. The company is said to be working now on using this information to identify conditions such as sleep apnea.
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