Since the v20.32 update my 255 doesn't record overnight sleep or overnight HRV anymore, but still counts bogus naps

9170481 23 days ago

Since the v20.32 update my 255 doesn't record sleep or overnight HRV anymore.

It measures heart rate and respiration and guesses sleeping stress levels, but no matter how much I restart and reset my watch, it always claims I didn't sleep all night and never measures overnight HRV.

It only reports sleep when I'm wide awake, with Garmin Sleep Coach warning me about the ill effects of naps that only happened in Garmin's imagination.

It did measure sleep and HRV (and bogus naps) before the firmware update.

Any fix for this? Or a way to roll back the firmware to the previous version? Or is missing sleep data and bogus naps a Garmin shortcoming that long distance runners with low resting heart rates just have to live with?

0 ovekvam 23 days ago

How low is your resting heart rate?

0 9170481 23 days ago in reply to ovekvam

Depends on training but usually between 36 and 40 bpm when I'm sleeping or netflixing on the couch. Double-checked by comparing my Garmin reading to old-fashioned counting with a stopwatch.

0 ovekvam 23 days ago in reply to 9170481

I have had 39 bpm average over a week with no issues related to sleep or HRV data.

0 Lewis 23 days ago

this is because you need to enable HRV in the options settings, by default is disabled

0 9170481 23 days ago in reply to Lewis

HRV was enabled and still is enabled, but my Garmin won't measure HRV even though the settings say it should.

0 ovekvam 23 days ago in reply to 9170481

I guess the issue is the sleep detection. The watch will only measure HRV during sleep.

0 9170481 23 days ago in reply to ovekvam

Maybe I move a bit more in my sleep which makes Garmin think i'm awake? Or maybe it's something else? Breathing frequency? SpO2?

Garmin is really vague on all it's calculations and algoritms. As long as Garmin fails to publish how it tells being asleep apart from being awake in sufficient detail for troubleshooting we can only keep guessing.

0 ovekvam 23 days ago in reply to 9170481

I don't think it uses SpO2. The breathing frequency is HRV based, as far as I understand. I guess the sleep detection is calbrated for the average Garmin customer. For them/us it works very well. For untypical sleepers, it is probably quite useless. On this forum we have users who regularly get sleep detected when they watch TV, while others sleep without the watch noticing.

0 oBuTTuSo 23 days ago in reply to 9170481

Try to slightly change your sleep window, just to get it saved again?