How does poor sleep affect BBT results?


I'm so close to the finish line. My temps have been up and AF is due today. Last night I didn't fall asleep until 2:30am and I didn't sleep for more than 2 hours at a clip. I took my BBT at the same time this morning, but I def didn't have 3 hours of continuous sleep. My BBT took a nose dive. Now idk what to think. Is AF coming? Or did my sleep have a major affect? I hope it's the ladder... but I have a feeling it's AF :(

Why do you think?