Deep sleep accuracy?

It barely recognizes Time in bed not to even mention sleep stages. It is good for tracking resting HR averages over night, body battery but sleep tracking is a lottery wheel on this devices. One example for all from yesterday. :-)

From analyzing mine and talking to Garmin, I believe the Garmin software basically assumes sleep by lack of movement.  This is why mine, like yours, often believes I am asleep while watching a movie or reading.  And thinks I am awake 1/2 the night because I may be moving my wrist around in sleep.  As I mentioned if you expand your "sleep" hours on the chart like you posted above, to cover your full day, you will be surprised at how often you were asleep during the day!  These Garmin watches seem to have many of us routinely tracked as awake when sleeping and tracked as asleep when awake. 

This happens to me also. This morning it told me I had about an hour of deep sleep and after checking later the numbers have dropped three and now it shows zero minutes of deep sleep. Very confusing 

One of the biggest disappointments after upgrading to 945 was sleep tracking. On my 25$ Mi Band 4 fitness tracker, it was significantly better. 945 struggles to identify even time in bed, deep sleep is always zero or only a few minutes. Also noticed my sleep time and zones for the last night can adjust a few times during the day. 

I had a Forerunner 35 which showed about half my sleep time being deep sleep which seemed to coincide with my experience. 

I upgraded to Venu SQ. If I wake up in the middle of the night snyc, it shows about half or more sleep time as deep. I go back to bed, sleep the rest of the night and in the morning, what showed as deep sleep a few hours before now shows as not deep. 

I felt like the forerunner 35 was giving me useful information. I do not think the Venu SQ sleep data is useful at all.  

All these info about sleepstages is completely nonsense.

First, it’s very doubtful your watch (or any other consumer device) can accurately determine the sleepstages (according to sleepexperts)

Second, there isn’t much you can do about. Well, maybe don’t drink alcohol because that influences the amount of deepsleep. But furthermore, you cannot train to sleep deeper or have more rem sleep. So you cannot do anything with the numbers your watch produces.

What is interesting however, is the amount of time you do sleep and the amount of time you are awake in the middle of the night (but still laying in bed)

Both these things are not very well or at all detected by a garmin watch.

So, in the end, sleeptracking is useless.

In my opinion, the important thing is to insert the quality and quantity of sleep in the post workout recovery, the rest only statistics

I have posted before that my experience with the sleep stats given by Garmin's devices are really just for entertainment purposes.  Because they go almost entirely by movement the accuracy is just not there.  I have had it monitor me during the day when I am up and about normally and it usually detects me sleeping when I am sitting still reading or even driving.  It is all about movement with my Forerunner 245.  At night when I am really sleeping it often detects me as awake.  I think this is because I move my arms some when sleeping and it senses that as awake. Also, when I first look in the morning, there is usually much more deep sleep indicated that later after Garmin analyzes and changes the data.  At first there might be an hour or two of deep sleep, then later it will change that to show only a minute or two.  

Bottom line  for me is not to pay attention to the watch sleep function.  It does not work accurately at all.

The big problem is that sleep influences the recovery time, today the watch marked only 30 minutes of deep sleep and improved my recovery by 5 hours. Deep sleep is responsible for regeneration and how it can improve my recovery. Garmim fixes it, even the cheapest Chinese watches are more accurate.