Why is it that I was so tired and almost falling asleep when my daughter was up now that she is…

Why is it that I was so tired and almost falling asleep when my daughter was up now that she is asleep and I was getting ready for bed and lay down I am not sleepy anymore why!!!! ugh well being on here won't help me get to sleep. well I am going to try to pass out in my husband arms because that always puts me to sleep night everyone.