Apple Watch Fitness App

I get notifications in the middle of the night saying "Its Time to Stand!" - It seems like the time on my watch isn't sync'd to the fitness app or it wouldn't be asking me to stand or exercise in the middle of the night. Why is it doing this and how can I make it stop? Or is it the fact that I get up in the middle of the night to go to the bathroom that is causing this? Thank you in advance for helping me.