When I'm too excited about WILDing and can't fall asleep bacause of that, I just tell myself I'm not wilding, just going to sleep normally. When I calm down and starting to fall asleep, I start with my mantra and I pay attention to the fog and images behind my closed eyelids and continue with WILDing.

Once I had a chime playing every half an hour or so, but I couldn't fall asleep because of the anticipation, when is the chime gonna sound again. But it may work for you.