I absolutely have what I term as unreasonable fear. Because they are not part of something that makes sense, like if a stranger was rattling the doorknob - reasonable fear - suddenly being totally aware of not being alone (when I am alone) unreasonable fear. If I go to work today, I will die (unreasonable fear) ghosts follow me so that I can help them. etc. For me, I think it is part of the delusional part of bipolar 1. Talk to professional of course, but yes - this is common in my opinion.

Best of luck to us all.

(edit added: I keep a notebook, that I made into a graph to chart my daily physical and mental symptoms and unreasonable fear and unreasonable anger are 2 things I chart)