After some setbacks trying to get the device to work properly, I tried wearing it while I slept, just to see if I can get it to collect data for a long time, and also establish a nice resting baseline.
I wore it for ~3hrs on my left calf (watch on wrist) while I slept. Intentionally, I set the alarm for 1 a.m. (time on chart is not correct time of day).
My initial thoughts are that the data is surprisingly noisy for sleeping, and does have a couple outliers, but they don't concern me. Also surpisingly, but positively, is that you can kind of tell how long it took me to fall asleep, and where I aroused to hit the snooze when my alarm went off.
See attachment for graph.