If I wear my smartwatch (Huawei* Watch 2 Sport) to bed, it will show me a report on my sleep. It shows light sleep, deep sleep, and REM sleep over time. How does something I wear on my wrist know this?
*Hopefully it is not sending my sleep data to the Chinese government.
It doesn’t know how much you sleep, but it does know when you’re moving around. So if you’re lying absolutely still for a period of time it assumes you are asleep. If you’re moving, it assumes you are not.
Jenny
your humble TubaDiva
But how can it tell the difference between light, deep, REM? I figured you needed an EEG for that.
The Fitbit tracks sleep stage based on heart rate variability that occurs during each stage – I’d imagine your smartwatch uses a similar methodology.
My fitbit can tell the difference between sleeping and taking the device off and setting it down overnight. But it isn’t using heart rate to distinguish, because I have a cheap, bottom tier fitbit that doesn’t have that feature.
My guess is that it’s looking for some movement, but not too much.
My Fitbit also doesn’t do heartrate. I specifically got it to track sleep cycles. It sort of knows when I’m “restless” at night. But it misses a lot. All too often it’ll think that I’m asleep most of the day and other stupid stuff.
Have you tried comparing it to an actual EEG of your sleeping brainwaves? If you had I think you would have discovered that the answer is “It makes a rough guess.”
An EEG is not something you just casually decide to go do. I had one 40 years ago, so no, I haven’t compared it.
I am not a calm sleeper - I toss and turn quite a lot. My fitbit rarely tracks my sleep properly. It thinks I only sleep an hour a night, or maybe a tiny bit more. I usually sleep 6-7 hours a night.
It has a direct connection to Santa Claus, who sees you when you’re sleeping.
How Sleep Tracking Works for Sleep as Android, an Android sleep tracking app:
Okay, that made me smile.
NM
Well it was manufactured by one of the leading espionage companies, it probably tracks more info about you than just sleep habits.
I wasn’t expecting you to. It was just a rhetorical device to point out that the smartwatch doesn’t actually know how you sleep. It just makes a rough guess based on what it can detect. I.e mainly how much you move your arm, along what axes, and for some watches your HR.
I got my Fitbit to monitor my sleep. I have sleep apnea so I thought it would be useful. I have found it not very accurate. It has counted laying in bed reading as being in deep sleep. There have been nights when I got up because I was not sleeping, the fitbit recorded me sleeping all night long.
I don’t know how this particular watch works. But during REM your body is mostly non-moving, NREM involves more tossing and turning. And typically you cycle between the stages of sleep (e.g. awake-1-2-3-2-1-REM-1-2-3…). Maybe it makes a guess based on the cycling rate?
How do you mean? It isn’t invasive. I suppose if you’re billing for insurance you can’t just request it, but if you have access to one it’s a trivial procedure.
I mean that you need a doctor’s orders to get an EEG, and the way they do the test depends on what the doctor is looking for. I don’t know what you mean by “trivial.” When I had one, they had me stay up late at night and get up early so I would be good and tired. They needed an EEG while I was asleep. I can’t remember how long I was there, but it was more involved than getting a haircut.