I recently got a Lumia 640 LTE and a Microsoft Band 1, and was interested to see what it said about my sleep as I've had trouble getting off to sleep at night. I'd previously been using a Sony Xperia Z3 Compact with a Sony Smartband SWR10 and was averaging 6.5 hours a night sleep, but since I've been using the Microsoft Band I'm getting some very weird results. The last 3 nights it says I've had 13 minutes, 10 minutes and 6 minutes sleep respectively!! How can I possibly be having such a large difference in the time recorded? I'm sleeping the same amount of hours as before, so why and how is it recording such different results?