I bought my wife and daughter both identical new Apple Watches (S1 38mm) for Easter. My wife's watch has been fine but my daughter's has been draining fast. My wife's was fully charged around 11:00am yesterday. She wore it to bed last night and upon waking up at 6:00am it was at 47%. My daughter's was fully charged at 9:00am yesterday. By 6:00pm it was at 10%. We charged it to 100% by 8:00pm and she wore it to bed and at 6:00am this morning it was at 15%. She did not have anything special running in the background other than a sleep tracker (Pillow which my wife was also running) and she always closes all open apps when done using them. Any ideas why the discrepancy between the two watches? We will continue to monitor it for a couple days but if it continues at the same rate then I will exchange it.