Sheyan only realised after talking to Uncle Dasi that he had slept for more than 30 hours. Being as cautious as Uncle Dasi was, he would surely have sent Sheyan to the hospital if Sanzi had not told him that Sheyan had not slept for 3 days straight because he was taking care of business matters, so he would sleep for a long time.
Sheyan's "dormancy" this time was not without reason.
First of all, the difficulty of the apocalyptic world of 2012 was shockingly high. Tsunamis, volcanic eruptions, earthquakes -- these horrible disasters that would not be encountered in other worlds were common occurrences there. Even people as powerful as contestants would be killed in seconds, regardless of how high their HP and defence was.
Secondly, Sheyan had to face all the traps Bind laid down. That had squeezed out almost all of Sheyan's potential. Although Party Ace came out victorious in the end, Mogensha's death was a heavy blow for Sheyan.