See prior post for data acquisition instructions. The Bedtime setup takes 2 or 3 minutes prior to going to bed. Data analysis takes me about 15 minutes in the morning. It looks long and complicated but after you do it a couple of times it's pretty simple actually.
ANALYSIS OF DATA
You will need to print charts of the data from the Elite HRV app. Start the HRV app, tap the chart symbol at the bottom, between the home and plus symbols. Tap "recent entries," pick the time desired and tap it. You will have to wait a bit. When the Details page appears tap the "intrareading chart" line. You will have to wait a bit again. The "analyze" screen should show in 30 or 60 Seconds.
You will now need to set the chart options, this only needs to be done one time. At the top of the analyze screen is a chart options button, tap it. Set corrected off, HRV off, rolling average on, rolling duration 5 minutes, heart rate on. Tap done and wait until your chart reappears.
Take a screenshot of the chart. On an Android phone this is done by pressing the volume down and the power buttons at the same time. On an iPhone it is done by pressing the power button and home buttons at the same time. Print the screenshot on your printer. Repeat for any other sessions done during the night.
Here is what a printed chart should look like. https://www.dropbox.com/s/dgk6hwv474ojr ... t.jpg?dl=0
EXTRACTING DEEP SLEEP DATA FROM CHARTS
In the example above, notice on the top graph which is the 5-minute rolling average of HRV, at about 4:30 there is a dip lasting about half an hour. Look at the bottom chart which is the heart rate data and notice that it corresponds to a distinct flat spot with fewer artifacts, lower heart rate variation, and abrupt changes from the previous and post deep sleep data. On the sample I have two red marks indicating the start and stop of the Deep Sleep spell. They are at approximately 4:10 a.m. and 4:40. I estimated this to be 31 minutes of deep sleep. Repeat for the other chart sessions and add for the total deep sleep for the night.
A normal healthy young adult will have approximately 1.4 - 1.6 hours of Deep Sleep nightly. Deep sleep is marked by lower steady heart rates with little variation. There will also be fewer artifacts as during deep sleep since the body is completely motionless except for breathing. REM sleep is marked by higher heart rates, more heart rate variability and minimal movement, but not completely limp. This is why most sleep monitoring apps don't work well, they can't distinguish between REM sleep and deep sleep based on body movements or sound. Normally there are three to five sleep cycles per night; light sleep, deep sleep, then REM sleep. A normal person has the most deep sleep during the first sleep cycle with decreasing amount of deep sleep for subsequent cycles.