Henry didn't know how he was supposed to sleep when the anticipation of the following day was eating him alive.
He could only get a couple of hours of sleep at a time before he would find himself sitting up and staring at the small window, hoping that it would soon be sunrise. Then he could make an excuse to leave his room.
Those participating in the event at the palace were permitted to sleep in that day but there was no point when he had so much nervous energy he wanted to burn off.
It wasn't a matter of if he could face a wild beast or not but he was worried about getting into his head too much. It would be his own thoughts that would inhibit his victory.
The king was crazy enough to bring wild animals into the palace grounds. It caused him to worry about what would happen if one of the beasts tried to attack the audience. He wondered if anyone would be able to have his back if he stumbled and fell.