Heart Rate Chart different from Target Heart Rate Chart

[lisamea]

I just noticed this a few days ago and have been checking ever since. When I look at the heart rate chart from the home page of the app and compare it to the target heart rate zone chart (accessed through zone minutes on the home page) they are different. The daytime measurements match, but during the night the heart rate zone chart is showing big jumps in my heart rate that the other one doesn't show at all. Can anyone explain why they would be different?

[LZeeW]

Hello @lisamea and welcome to the Community.  Users have been complaining about those early morning zone minute spikes for months.  It doesn't matter what model Fitbit you use.  I have Premium, so I get a sleeping heart rate graph as part of the advanced sleep analytics.  My sleeping heart rate graph never shows those early morning spikes or that very saw tooth pattern.  I have never seen a comment from a moderator acknowledging this issue.  I just ignore it.