Sleep Watch wakes me

I am trying to figure out how to use the Sleep watch on the apple watch?

I click Start Sleeping, but then it takes me to an ad to upgrade. So I wear the watch when sleeping, and in the AM, it had recorded my sleep. Problem is, in the middle of the night the watch buzzes me telling me to stand! I DON'T WANT TO STAND - I AM SLEEPING!!!!

So how do I get the wtach to let me sleep, but then record my sleep?