I mean, if you had a Darkrai, took really good care of it, let it roam around with you, and kept it close at all times... Don't you think you'd have a hard time falling asleep with them out of their pokeball? I mean, yeah, obviously, but he had taken the chance to snag or use one of the Lunar wings so that you no longer fear of falling asleep next to your main 'mon.
This comic was poorly done tho :U