Slaughterhouse Five-time travel?

"Under morphine, Billy had a dream of giraffes in a garden.  The giraffes were following gravel paths, were pausing to munch sugar pears from treetops.  Billy was a giraffe too." PAGE 99

This brief part of the novel was a little odd for me.  I thought that the time travel stuff was weird.  Billy kept ending up at different parts in his life without warning.  Not only that, but he also thought that he went to another planet.  This was very strange to me that someone could firmly believe all this was happening.  The ironic thing about this quote is that he was under morphine when it happened.  One would have thought that he would have thought about something super crazy while he was on the morphine, but I was a little disappointed in the creativity he was able to conjure.  What he believed to be real life was crazier than what he thought on morphine.  The idea of being a giraffe was rather normal compared to what he thought was actually real.  I was hoping for a little more extreme adventures while he was on the morphine.  I think this shows how confused and messed up he has become as a result of the war.