How is deep sleep differentiated from light sleep?

I had a Galaxy watch before this one. The sleep stats were pretty similar to what I get on the Active 4. I feel like the ability to measure this is not an exact science for any watch manufacturer.

9508695 said:

At 6 am it showed 3 full hours of DEEP + 3 full hours of LIGHT, starting from 12pm, nothing ELSE.

But at 9am, it showed 25 minutes of deep, 1h of rem, 6u43m of light, 2u12m awake, starting from 11pm.

So it would seem they are not comparing to any already recorded data from weeks and months, but just the last couple of a few hours.

Unbelievable results all over, even about breathing, and stress (supposedly their extracted HRV).

HI there! I have a case regarding this and I would like to add you to it. May I reach out and grab some information from you. 

Hi Garmin-AmberD I also see these symptoms if you want to add me as well. Interestingly it is not every day.

sure

Yes this is normal for my Forerunner 245. And as I have noted above and in another thread, I conclude that the sleep features on these Garmin devices are not to be taken seriously.  For me and many others, the accuracy is so off it is almost comical.  Try this for entertainment - Set your sleep time for the middle of the day and then notice how often you were asleep when driving, reading, sitting at the computer, etc.  Garmin seems to use movement to determine sleep so it simply does not work for most people.  

Because I move my arms fairly regularly when asleep, I am shown as awake for many hours at night when I was really sound asleep. And it shows almost no deep sleep at all for the same arm movement reason.  

Yes, a quick Google search gave me multiple articles about sleep tracking on wearables. "relies on a tri-axis accelerometer, which monitors your movements and can tell with relatively good accuracy if you’re awake or asleep. Most smartwatches have heart rate monitors as well, which helps with sleep tracking accuracy."

This goes for many of the metrics. Stress, heart rate, sleep, SpO2, breathing rate, calories, and even steps. It is made to work for a typical customer, and there will always be some customers it can not measure properly. I am lucky to be typical enough to get quite accurate readings.

Maybe but there sure do seem to be a lot of atypical customers. I know with me even though I am a sound sleeper, it has almost zero accuracy.  My resting heart rate is in the low to mid 60s when awake, low 60s when sleeping so not much for the watch to detect there.  My respiration is fairly level and consistent also.  The pulse ox is not accurate anytime for me so I never even look at that.  I sleep on my stomach with arms under pillow so I think I probably move my arms more than typical.  That is enough to throw the watch completely off I guess.  I have had many people who use the Oura ring tell me that it works well.  I have not tried the ring since that also bases sleep on movement of the hand wearing the ring so I expect I would have the same problem as with Garmin.  Bottom line is that the tech to really tell you how you are sleeping is not there for the consumer yet.  If you feel you are not sleeping well, a sleep lab study is probably the only way you are going to know for sure.  Of course the issue with that is they usually involve sleeping in a lab so I doubt I would sleep normally for the study if I did it.  I have heard that some sleep professionals send you home to sleep with tech that you hook yourself up to.  That might be the way to go. I feel that regardless of what my Forerunner tells me, I sleep well enough.  I wake up naturally on my own after 7 to 9 hours and wake up briefly maybe once or twice during the night.  I am never tired during the day and that supposedly is the biggest warning sign.

WTAFT said:

ottom line is that the tech to really tell you how you are sleeping is not there for the consumer yet.  If you feel you are not sleeping well, a sleep lab study is probably the only way you are going to know for sure. 

100%. You have to know what you are getting with a wearable and interpret the results accordingly.