This is what my watch (Huami Amazfit Stratos) and the corresponding app tell me about how I slept yesterday.
Predominant light blue areas are dubbed as "light sleep" while dark blue stripes are "deep sleep".
The orange area in between is "awake period" because I did the sleep in two parts that night.
I don't know yet how the watch really does the measurement and if these patterns are in any way correlated with NREM and REM sleep phases.
Will learn more and come back to you.
