What did King Darius do on the night Daniel was in the lions' den?

Answer: Fasted and could not sleep

The king spent the night fasting, with no entertainment, and sleep fled from him. At dawn he hurried to the den.

“Then the king went to his palace and spent the night fasting. No entertainment was brought before him, and sleep fled from him. At the first light of dawn, the king got up and hurried to the den of lions.”— Daniel 6:18-19 (BSB)