Does a polygraph test work in a highly emotional state?

I ask because I was surprised when Dr Christine Blasey Ford testified today that she underwent a polygraph test on an emotional day when she attended a relative's ( I think it was her grandmother) funeral.

Also Dr Ford said she was very scared of flying - and she had the polygraph the same day she was flying to New Hampshire.

I know little about Polygraph Tests - but I would think the results would be less accurate if the recipient was stressed out about flying and had just attended her grandmother's funeral.

Does anybody know?