@markgurman I’d buy this in a, uh, heartbeat for sleep tracking and sleep cycle-driven alarms. Yes, it would be in addition to the watch which is just too much to wear to bed.
I don’t see myself wearing something like this during the day, the watch seems to cover what I need…but I’m old enough to never say never.
I could also see this as a way to move sensors off the watch, making it much thinner and lighter if they’re sold as a pair.