“No sleep data detected last night”

So a number of people have shared the answers and have given permission to acces data, should we understand your request for more people as an indicator that Garmin has no clue what is causing this issue for us? (meaning this is issue will probably be there wil much longer...?)

No, it just means that, speaking for myself, it takes time to reproduce the problem (i.e., since it seems to be correlated to 9+ hours of sleep, I, for one, simply haven't had that in the past three weeks). Garmin support is closely following this issue and have enabled (again, speaking for myself) more diagnostics on my watch so that when the issue happens again, they can look at the diagnostic data.

On a general note, I wish people in this forum would stop assuming that Garmin is “clueless” or that they need to do this or that (training readiness. There is likely a marketing reason why this is not on the 255. You knew before buying that it is not a feature, so don't expect to Garmin add it at your discretion). Let's keep this forum a helpful place without bitching and moaning.

1. Yes 

2. Yes my sleep window is set 11.30pm - 9:45am on weekends so I can catch up on sleep. Slept from midnight ish to 8:15 GMT/9:15 BST- clocks went back an hour in the UK at 3am this morning, this is not the first time sleep was not detected after a long sleep, disappointing as it has been telling me to get more sleep all week and it was the best sleep I’ve had all week. Update: Literally since writing this it has updated my sleep but it hasn’t taken into account the extra hour now, so when I’ve slept 9 hours with some waking moments it’s come up 6h 42 which should be 7h 42 at least. As mentioned, this has happened Tuesday 22nd, it recorded me as being awake from 4:39am which is when I got up to use the bathroom briefly in the night, and has me as falling asleep at 2:33am when I fell asleep around 9:30-10pm.

I upgraded from the forerunner 55 to the 255 because there was no strength training for gym workouts, but have to say the sleep tracker on the 55 seemed to be a lot more accurate and reliable. 

3. Yes

4. Yes

Came here today searching for an answer. I've had this happen a couple times recently including last night. I definitely was not over 9 hours of sleep. It was more like 7.5 - 8 hrs. 

We all have different expectations, but I think basic features, like sleep tracking, should always work. Apple and Google set the standard—I don’t recall my iPhone being unable to make calls for a month.

I get that beta features may be unstable, but this is core functionality that used to work. It’s fair to expect Garmin to fix it quickly, especially since missing sleep data affects the accuracy of overall recovery and training insights.

After an intense weekend training I took a very long sleep last night. Over 10 hrs, recorded without issues. So the ">9 hr is not recorded" theory is not always true.

Version: 20.32. (Garmin: feel free to review my data, and contact me)

In personal communication, Garmin officer also told me it is not about 9 hours. They were aware of the problem and they had been trying to find a solution. 

This continues to be a really annoying issue. I find the Watch uncomfortable to wear at night but am trying to get used to it and it’s beyond frustrating that it keeps getting this so off, like enraging to see it tell me I’ve had poor sleep yet again; I’m on annual leave today so I’ve actually slept from 10pm til about 9:20am, as I needed it. The watch says I was awake at 6:12am, I didn’t even get out of bed, I was up once at 3:30 and was out the rest of the time. It has registered a nap 2hrs after for an hour around 8:10-9:15 but is saying I’ve been awake from 6am-8am which is baffling. Even after manually adding my other ‘nap’ it’s still telling me my sleep was poor and also is not providing stats for those ‘naps’- my sleep window was still set 9:30-7:45 as a rough weekday window and I slept beyond that but I wasn’t up at 6am and that was still well within the window