When you sleep several body processes change. Among them, the body temperature decreases, pulse changes, overall body motion changes, and those are tracked.
It’s crucially important to know that they 1) measure certain things (with a margin of error*), and then 2) make a whole lot of assumptions based on those measurements.
Sleep is deduced by heart rate data, and depending on product, can be massively off: in many cases, reading in your bed has your heart rate so close to what it would be when asleep that the appliance misinterprets what’s going on.
Another figure they present, seemingly convincingly, is calory consumption, but basing your eating on those assumptions is far from recommendable.
Some sport watches assume that certain types of arm movement mean walking or jogging, resulting in magnificent activity results after two hours of knitting.
*As an example, a watch whose sensors try to get your heart rate by peeking through your skin to see a pulse, can be off by 30 to 40 beats per minute, if the watch is worn too loose, if it doesn’t fit your wrist area properly, or if your hands are cold enough. Even though the data may be crap, the unit will still display the numbers with the same convincing style as it does when conditions are perfect and the data is actually good.
The short answer is they don’t. To get true sleep data you need to be hooked up to a brain monitor at the very least.
The longer answer is that they make a series of educated guesses based on what we know typically happens to a lot of people while sleeping.
You shouldn’t and outright can’t rely on health monitors to give you accurate sleep data. But you can use it to monitor trends. If the data it collects suddenly changes, and you notice a change in your own mood or energy levels it’s usually an indicator that something isn’t right. Then you have to try and track the issue down yourself.
If you have trouble falling asleep they will track it as sleep if you are restful during that time. Similar if you wake in the morning but try to go back to sleep. As someone who had trouble falling asleep, it could end up reporting an hour or two extra sleep at the start of when I tried compared to what actually happened.
It seems to work best if you have a very clear separation between awake and going to bed. For instance I tend to read or relax a while in bed before I sleep. My watch has trouble deciding what is sleeping vs laying around with 61bpm. If however I am busy around the house until I actually want to sleep. (70s and 80s bpm and then dropping into my sleep rate) my watch picks up on it better.
Blood oxygen + body temp + pulse + movement sensors + knowing ur routine when you often stop moveing alot and it all just kinda a guess really, a brain scan would be the true way to determine if ur alseep or not
I often watch movies in bed before i go to sleep and almost all of the time my Fitbit says I’m sleeping. So it says I sleep 10-11 hours a night. Obviously very inaccurate.
Most of these devices use a sensor called a PPG. PPG sensors use red or green light to sense blood flow right under the skin. By measuring the intensity of the light that gets reflected back the device can collect data on blood flow, pulse, blood oxygen levels, and can use that to extrapolate many other kinds of data.
When you fall asleep many processes in your body slow down such as pulse, respiration, and your body temperature decreases too. The PPG sensor can detect all of these and recognizes all of these changes together as your body falling / being asleep.
Comments
When you sleep several body processes change. Among them, the body temperature decreases, pulse changes, overall body motion changes, and those are tracked.
It’s crucially important to know that they 1) measure certain things (with a margin of error*), and then 2) make a whole lot of assumptions based on those measurements.
Sleep is deduced by heart rate data, and depending on product, can be massively off: in many cases, reading in your bed has your heart rate so close to what it would be when asleep that the appliance misinterprets what’s going on.
Another figure they present, seemingly convincingly, is calory consumption, but basing your eating on those assumptions is far from recommendable.
Some sport watches assume that certain types of arm movement mean walking or jogging, resulting in magnificent activity results after two hours of knitting.
*As an example, a watch whose sensors try to get your heart rate by peeking through your skin to see a pulse, can be off by 30 to 40 beats per minute, if the watch is worn too loose, if it doesn’t fit your wrist area properly, or if your hands are cold enough. Even though the data may be crap, the unit will still display the numbers with the same convincing style as it does when conditions are perfect and the data is actually good.
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The short answer is they don’t. To get true sleep data you need to be hooked up to a brain monitor at the very least.
The longer answer is that they make a series of educated guesses based on what we know typically happens to a lot of people while sleeping.
You shouldn’t and outright can’t rely on health monitors to give you accurate sleep data. But you can use it to monitor trends. If the data it collects suddenly changes, and you notice a change in your own mood or energy levels it’s usually an indicator that something isn’t right. Then you have to try and track the issue down yourself.
If you’re not moving and your heart rate slows a bit and maybe temperature dips, you’re probably asleep.
They only kind of know.
If you have trouble falling asleep they will track it as sleep if you are restful during that time. Similar if you wake in the morning but try to go back to sleep. As someone who had trouble falling asleep, it could end up reporting an hour or two extra sleep at the start of when I tried compared to what actually happened.
It seems to work best if you have a very clear separation between awake and going to bed. For instance I tend to read or relax a while in bed before I sleep. My watch has trouble deciding what is sleeping vs laying around with 61bpm. If however I am busy around the house until I actually want to sleep. (70s and 80s bpm and then dropping into my sleep rate) my watch picks up on it better.
Blood oxygen + body temp + pulse + movement sensors + knowing ur routine when you often stop moveing alot and it all just kinda a guess really, a brain scan would be the true way to determine if ur alseep or not
I often watch movies in bed before i go to sleep and almost all of the time my Fitbit says I’m sleeping. So it says I sleep 10-11 hours a night. Obviously very inaccurate.
Fucking guessing.
Sorry tired today didn’t sleep well, don’t need a ring or watch to tell me that. Now excuse me I have some clouds to yell at.
Most of these devices use a sensor called a PPG. PPG sensors use red or green light to sense blood flow right under the skin. By measuring the intensity of the light that gets reflected back the device can collect data on blood flow, pulse, blood oxygen levels, and can use that to extrapolate many other kinds of data.
When you fall asleep many processes in your body slow down such as pulse, respiration, and your body temperature decreases too. The PPG sensor can detect all of these and recognizes all of these changes together as your body falling / being asleep.