Sleep time
Klaus was prepared to go the extra mile to seal a victory in this event for several reasons. For one, he had a goal in mind that could only be achieved with him being at the pinnacle of the school and with the perks that came along with being the number one student, he knew he could not pass up this golden opportunity.
The skill he was using now dubbed the "Tiptoe (Shadow Tsunami)" was by far the biggest skill he had in his arsenal as of now. This skill was unlocked as a reward for surviving the encounter with a divine being which occurred in the pod hours during the day time.
Unlocking a skill as powerful as this just for surviving an encounter with a being classed as more powerful than he was meant that it was quite big of a deal. Frankly, he too believed that the system gave prices or rewards based on a tit for tat modular. In a way, he only ever got something from the system by doing something asked by the system.