I slept with my watch for first time ( he he). I wish the watch had sleep tracking since I currently use a jawbone up 24 for that purpose. I guess in anticipation of the watch one day having this function I decided to try sleeping with it last night. I also like waking up from the vibration instead of an audible alarm. I completely charged the watch before going to bed and put it in airplane mode as well as do not disturb and set an alarm for this morning. It worked well and thought I would share with this community how much of the battery drained over the 7 hours of sleep. I was surprised it drained only 3 percent. It was nice having my heart rate tracked during the night. It did do something a little weird though. I did get credit for 2 hours of standing. I assume this is from tossing and turning. I look forward to apple enabling sleep tracking soon since it really is not much of a battery drain at all. I think I will continue using it as my alarm clock until that happens. I will charge my watch when I get home from work as I get caught up on the news or browsing on the iPad. (About 1 hour). I also will top it off about an hour before bedtime .