I used to wear a watches everyday for fashion more than anything, then I swapped them out for a Withings Pulse.
I'm in the same camp as others though, never sleep with them on, I just take them off at night, and, in the case of the Withings, put it on to charge on my bedside table. Even though I know it has a couple weeks of charge, I'd rather not have to remember to charge it every other week, so every night works better for me, so nope, not worried about battery life at all, in fact I'm hoping with the fewer times I'll be looking at my phone, it'll end up helping me save battery life on that.
I'm in the same camp as others though, never sleep with them on, I just take them off at night, and, in the case of the Withings, put it on to charge on my bedside table. Even though I know it has a couple weeks of charge, I'd rather not have to remember to charge it every other week, so every night works better for me, so nope, not worried about battery life at all, in fact I'm hoping with the fewer times I'll be looking at my phone, it'll end up helping me save battery life on that.