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Selected sleep metrics comparison: Garmin Epix 2 vs Fibit Charge 5

Etupes25
over 1 year ago

TLDR: The Fibit does a better job at measuring awake time during nights, but is worse at avoiding sleep while watching TV. Sleep score are about the same. No need to complement the Epix with Fitbit for better sleep data.

As I am working though sleep therapy (CPAP machine), I have been watching my sleep data closely. I am not happy with the Garmin Epix 2 sleep metrics on 3 main areas:

Fake Nap Problem: the Epix can falsely detect sleep during the day, and overwrite the sleep metrics

TV Problem: the Epix can detect sleep while I am watching TV in the evening prior to going to bed routine. It typically gives me good deep sleep during that time

Awake Problem: the Epix awake time detection during the night is pretty bad. This is the only sleep phase I am aware off. Clearly the Epix doesn't know I am lying in bed waiting to fall back asleep.

To address the TV and Awake problem, I decided to test the Fitbit Charge 5. The device is well rated by others on the detection of sleep phases compared with the Epix.

For the last 3 weeks, I was wearing both devices at night, and recorded the results in the morning, along with my subjective sleep score: 50 (horrible night), 60 (bad night), 70 (ok night), 80 (decent nigh), 90 (great night). This is subjective based on how often I woke up, how long it took me to fall back asleep, and how I felt when waking up.

For 19 nights out of 24, I was wearing the watches while watching TV. For 5 nights, I forgot to put them on and started wearing them as I went to bed.

The Fitbit Charge 5 does a better job at measuring awake time (after correcting for the TV problem)

- the Fitbit records more awake time during the night, subjectively closer to what I am aware of.

- I am suspecting that the Garmin is confusing awake time with REM too often

- Deep and Light sleep are roughly the same, although the Epix gives me more deep sleep time (watching TV deep sleep time has been excluded here).

- Because awake time is not included in sleep time, Garmin Epix slightly overestimates my total sleep time over the test period

- The TV Problem is a wash. It happens more often with the Fitbit, as it wrongly detected the start of sleep while watching TV 58% of the time, vs 37% for Epix. The Fitbit also missed the wake time more often (21% of the nights) than the Epix (11% of the nights). The TV problem doesn't impact the sleep score of the Fibit much, if at all because the TV sleep or missed wake time sleep is actually full of awake time, unlike the Garmin. So I wouldn't need to correct the sleep time with the Fibit is much as I need with the Garmin when the error happens.

- After corrections, the sleep score of the Fitbit is closer to the perceived sleep quality than the Epix, but not in a striking way

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  • 0 over 1 year ago

    sorry - is the summary that they re both as bad as each other?

    Must admit I pretty much just focus on Stress during my sleep period and leave it at that.

  • 0 over 1 year ago in reply to jaamgans
    jaamgans said:
    is the summary that they re both as bad as each other?

    Certainly not worth buying a Fitbit to monitor sleep when I already have an Epix! The sleep tracking is better, but not better enough.

  • 0 over 1 year ago in reply to jaamgans
    jaamgans said:
    is the summary that they re both as bad as each other?

    That's very much the case for all watches used to determine sleep. No watch measures sleep. Watches determine sleep from estimation of HRV derived from the colour change as blood pulses under the skin. True HRV can only be measured by analyses of the electrical signal from each heart beat. So, all-in-all, determination of sleep and any associated sleep cycles from optical heart rate is totally derived from algorithms that are developed from research. The start point for getting a good heart rate from OHR is therefore the quality of the skin contact of the device, the nature of the skin under the watch ie light, dark, hairy, tattooed etc, amount of subdural adipose tissue, and vasculature.

    And, as we can see from posts in the Garmin forum, and others including the much vaunted Apple and Fitbit, success is not guaranteed for every one.

  • 0 over 1 year ago

    I don't buy a sport watch for sleeping :-)

    But, yes, Epix is not perfect about this measure like Fitbit suks about all sports and health measures ;-)

    If you search the best health and sleep traking, look at the brand Withings.

  • 0 over 1 year ago in reply to DreammerX

    I agree. I am not interested in accurate sleep phase analysis as there is not much you can do about them, aside from admiring the results.

    I was more interested in the sleep score as it is expected to reflect sleep quality and is central to training readiness.

    I learnt that despite inaccurate sleep phase tracking (in particular time awake), the Epix sleep score is plenty good enough for my purposes: optimizing my sleep therapy and my training.

  • 0 over 1 year ago in reply to DreammerX

    Not with their watches, though. 

  • 0 over 1 year ago

    Regarding TV time counting as sleep time, how have you set your watch's sleep time? Are you watching TV within that time period? I ask because I've never seen either of my Garmin watches (Epix and Fenix 6) count TV time as sleep time.

  • 0 over 1 year ago in reply to 7017726

    My sleep mode schedule is 1am to 8am. I typically start watching TV around 9:15pm and go to bed around 11:15pm. I have read that the sleep mode schedule is supposed to heighten the sleep detection, but changing it has not impacted at all the TV problem.

    On the fitbit, there is also a sleep schedule, but it is optional. There are also 2 levels of sleep detection: normal and sensitive, which seem to depend on how sensitive the sleep detection is to movement. These settings made no difference to me during the trial period.

    As I said before, the TV problem happens more often with Fitbit, but is less disruptive to the accuracy of the sleep score, because the Fitbit marks a lot of awake time during that time, unlike the Epix which marks a lot of deep and light sleep.

  • 0 over 1 year ago in reply to 7017726

    Interesting question as I frequently overlap watching the goggle box with my scheduled sleep time of 2130 and, more often than not, read before sleeping. This morning we also had a lazy extra couple of hours in bed reading well beyond the scheduled wake time of 0630. Despite lounging in bed for those hours my watch still showed my sleep as ending at 0640.

    I can't say I've never had an issue with sleep time being recorded when not asleep but it's very rare. That said I got very tired some weeks ago and had a nap around 1800 for close to an hour. The watch carried that on into my sleep for the night.

  • 0 over 1 year ago

    I have been wearing a Garmin ForeRunner 255 and a Fitbit Charge 5 for 6 months 24 hours a day. The sleep scores and data seem to have nothing in common at all. The only concrete observation I have is Fitbit tells me my sleep has been pretty good when my head tells me I was awake most of the night. Just had a terrible few weeks of sleep and Fitbit scores of 70-80, meanwhile Garmin is reporting values in the 40's. Verdict - the Garmin score seems to reflect how I feel whereas the Fitbit scores seem like nonsense.