This is the second time that I go to sleep only to wake up to find out that there was no HR measured, no sleep tracking, no HRV, no nothing! 
I don't want to be coming to this forum to rant but I am honestly starting to feel that I cannot trust this watch and I have to always keep an eye on it to make sure that HR is working, that I need to restart it periodically etc. This really sucks for a $600 piece of electronics.
