Deep sleep stages not recognized

That's because in VA4 (starting from VA3 actually) the system recognizes 3 sleep stages - deep, light and REM. Somehow most of sleep is usually REM, I rarely get over 1 hour of deep now (used to have 2-4 hours on my VAHR). A few minutes of deep sleep a night is on the extreme, but it happens once in a while as well. 

I check the sleep stats just after waking up and after few hours. Seems that Garmin postprocesses the data in the cloud and changes it a lot - moving the sleep start time much earlier than the real one, but after correcting it manually I get very few deep sleep time - like 15-30 mins.

Me too

Maarten_A I think that anyone who get correct estimate of total sleep hours is already lucky one :) Also I wouldn't pay much attention to sleep stages at all, unfortunately there are few wrist wearable devises which can make good estimation of sleep phases these days, you may like to watch this video, this guy is testing with EEG https://www.youtube.com/watch?v=NYuF1jkvDPQ
Also I have a feeling that if you have relatively regular sleeping time Garmin can do relatively good job in calculating sleep hours but if your sleep schedule isn't regular it can be pretty bad. myself  I get around 4 hours of extra sleep which I don't mind to have in real world and not just in the stats.

5270954 yup, they definitely do something with the data, and most of the days it just make things worse, but today was the first time when they actually cut few minutes from my sleep which was correct move as I already was wake up. their estimation is still wrong but at least it didn't get worse as usually.

And unfortunately this problem is common and it seems that people with irregular sleep schedule is suffering from it. Myself I think that first estimation we see comes from FirstBeat metrics which is used for BodyBattery calculation and  then calculation is done using some other mechanisms on the server, possibly using profiling or something.

I checked my sleep data for the last few weeks, and my wake up times are within +-2 minutes of the correct time every day. The bed time estimations are well within 10 minutes. The stages also look correct. I can recognize the cycles of around 1.5 hours, and the deep sleep is mostly at the two first cycles. At nights where I feel like I didn't sleep so well, there is less deep sleep. But then again, I am a regular sleeper. 

I usually don't check the sleeping statistics before syncing after my afternoon workout.

wow ovekvam , that's really cool to hear, I'd be more than happy to have such a low error. +-2 minutes sounds like a dream to me. That's another good motivation to become a regular sleeper

As for myself I specially make a screenshot during the first sync and then check again later to see how the data was adjusted.

ovekvam I wonder if your sleep hours set in Garmin Connect actually correspond to your real sleeping hours or not? I've tried to set mine as close as possible to when I sleep to have best possible results.

The watch is more likely to miss sleeping outside the set sleeping hours. And if you lie down very still in the sleeping hours, it will often think you are sleeping, even if you are awake.

mine are thinking that I'm sleep even if I type on my keyboard :P