He's 198 all of the time.
No graphic changes, but when he is sleeping, he is in a sitting animation.. that is why he looks like he is dead. The Velious Dragons all have a sleeping animation too, different than death position.
Also, he is only in certain zones, so if you're sitting there doing #race 198 in Najena, you're not gonna find him.
But if you're doing race in Sleepers, and he's not showing up as 198... well, I've known a lot of people unable to see his model. I've heard you need to run optional patch to get it.
I've seen plenty of people who are unable to see Sleeper, Jaled-Dar, and Zlandicar/Yelinak, they all appear as humans.