My friends wondered if I had taken leave of my senses.
take leave of (one's) senses
To do something strange or outlandish. Have you taken leave of your senses? You can't just give up surgery to move upstate and paint landscapes!
take leave of one's senses
Fig. to become irrational. (Often verbatim with one's.) What are you doing? Have you taken leave of your senses? What a terrible situation! It's enough to make one take leave of one's senses.