@Kell64 Check your heart rate data. It sounds like maybe your heart rate monitor wasn't working last night, so that's probably why you didn't get any data.
Im havving a somewhat simmiler problem out of the 2 or so weeks i have had the charge 5 i have gotten 2 days where it even remotly recorded my sleep on its own but its only been for at most 55 min of recorded data but if i manualy ebter a log for my sleep time its actually gives somewhat accurate data.