Overnight HRV values are wrong

HRV is processed and calculated on the watch in real-time, hence any consequent changes of the sleep time won't have any effect, since Garmin Connect does not make any data processing. It merely displays what was already measured by the watch, and sent to the GC account. 

Thanks trux. Isn't this a huge can of worms though, as the sleep detection isn't super accurate for watches, which means most sleep scores and HRV avg values are wrong because they include the periods when you awake before sleep?

I am not quite sure the averages for the HRV status ought to be necessarily taken only during sleep. I'd tell it is rather done in this way only because it is easier to measure the HRV when you do not move. However, if you feel it impacts the results significantly in your case, you can suggest Garmin to allow a separate time range, narrower than the bed/wake-up times, or another method to assure the HRV is taken only during the sleep (if it is really intended to be taken in that way). Do not expect they will introduce a postprocessing in Garmin Connect, though - that's unlikely to happen. Suggestions are best done at Share Ideas | Garmin

Not an expert, but intuitively it does not make sense that recorded HRV values are higher or lower depending if the device got your sleep start time right. At best this introduces additional noise, worst case it completely skews the metric/measurements. Would be great if someone familiar or even Garmin can chime in.

Surely it doesn't take too much to calculate averages? There is already some level of "post processing" in GC e.g. when you update sleep times the sleep score adjusts. Stress during sleep also doesn't adjust even though sleep duration does which seems more likely to be an oversight than a design decision

My discussions through email support have been mostly template answers back but they seem to indicate that this may be an unintended error that can be solved by a hard reset. I'm hesitant to do one as if it does not work I'll have missing HRV and Training status data. 

Can anyone else confirm if they see this also, or its just me and something that can be fixed with a reset?

Update - there seems to be 2 issues. First is that HRV avg does not recalculate to adjusted sleep times. Second is the avg values don't seem to just be an average;

My sleep HRV from last night, no adjustment to sleep times. Manually pulling the values and calculating gets me 37.4ms avg, not 34. The only way I managed to get 34 is if i removed all entries that are outside my baseline (33 - 40ms) which makes even less sense.

I genuinely hope that I am the only one having this issue and an eventual watch exchange will solve it, but this looks more likely to be a software issue. If anyone can do a quick check on a few days of their HRV avg values it'll be much appreciated.

trux - also, i found this on the Garmin website:

https://www.garmin.com/en-SG/garmin-technology/running-science/physiological-measurements/hrv-status/

Compatible Garmin devices calculate HRV continuously while you are sleeping. When you wake up, you can view your average HRV calculated using data from the entire sleep period. You can also review a chart that shows how your HRV changed while you were asleep based on analysis of 5-minute time windows.

This offers a significant advantage compared to other methods that measure HRV during only part of the night, during specific sleep stages, or involve testing at specific times of the day.