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Accuracy of Sleep function

Former Member
Former Member over 2 years ago

Hello again,

I find that sleep detection on my FR255 isn't accurate.

For example, see below, this is my sleep report for last night. It says I pretty much slept continuously , however I know that this isn't true because between 3 and 5am, I was (continuously) awake listening to music and watching a movie on my iPad. Yet during this period, the watch recorded me sleeping.

Now, I have only been using the watch for a week and don't really understand how the watch "knows" if I'm sleeping*. Does the watch needs some kind of training period for accuracy to improve ? Or, are there settings in the watch that I overlooked that I need to look into ? I have already set my sleep hours from 11pm to 6am. I tried to help myself and looked in the manual but couldn't find much on this subject.

Some things seem to work nicely though, for example REM cycles normally are more frequent during the second half of the night, and deep sleep in the first half, and in my case, the watch has indeed detected that (almost) every day this week. Nice.

Thank you.

Jean.

* edit: the below article explains how it works.

https://www.androidauthority.com/garmin-sleep-tracking-3174562/

  • 0 over 2 years ago
    don't really understand how the watch "knows" if I'm sleeping

    It doesn’t. It is just guessing.

    And I am not talking about FR 255 in specific here, or Garmin watches in general, I am talking about ALL smartwatches and wearables.

    Please keep in mind, what these devices have: A pulse sensor and an accelerometer, that’s it, basically. So they will know, if your pulse is high, middle or low and they will know how much you move (your arm). How do you expect the device to really know from this information, if you sleep, are awake and stare at the ceiling or read a book? It can’t, cause it can’t see what you are doing and it can’t read your brains electricity.

  • Former Member
    0 Former Member over 2 years ago

    Ok thanks for the response. So I need to take the information provided with a big grain of sea salt.

    Noted, no problem.

  • 0 over 2 years ago in reply to Former Member

    I have a 255. It’s good for a laugh. Sometimes I wake up early, come downstairs, make a coffee and read. My watch has counted this on more than one occasion as deep sleep! Makes me doubt some of the other metrics based on sleep. It is great for running though, which is what I got it for.