I'm three nights into using the Index Sleep. This post is to highlight what's broken, but I'll include other reflections that could be useful for people.
My 'base line' comparison is wearing a VENU3 to bed every night since July of last year. Before that it was a VA4s for almost exactly 4 years.
First impressions:
Comfort:
Its much more comfortable than wearing a watch to bed. For the most part I don't really notice it. The only prudent advice thats missing from the manual is: If you're a side sleeper, wear it on whichever are is most likely to not be under you.
Build quality: The seam around were the sensor is exposed seems very much not durable. Only time will tell, but its hard to imagine this fabric sleave requiring replacement much sooner than other Garmin accessories.
Sleep tracking:
What works:
Regardless of when I go to bed, the start and stop are very accurately tracked to when I put the arm band on and take it off. Each time I put it on, I wake it up by putting my finger over the sense until it lights up.
All of the analytics and sensor tracking are within an expected range compared to the VENU3 (read: very little deviation)
What doesn't work:
Body battery: With the Index Sleep, my body battery has only recorded +17 to +25 which is 1/2 to 1/3rd what I was getting in previous nights with the VENU 3.
What really doesn't make sense about this is that all other metrics that would effect Body Battery are within an expected range VS. the VENU3 sleep tracking and the Index Sleep has seen me as having on very more restful sleeps (with fewer detected moments of wakefulness) than my VENU3. So how exactly does that result in less Body Battery.
It doesn't make sense.
I will give it a couple of weeks but unless that issue is fixed, there's no point keeping it.