Don't know why,but with my forerunner 645 sometimes the data in Garmin connect after I wake up it's accurate with the time I fall asleep and wake up but later on the data was all mess up,give me erratic data on the sleep. Now in the first night of sleep with the forerunner 745 the same bug,I had to change the time manually , because I don't know why the previous data the watch give me was erased . This is annoying