Actually, SP is the ultimate goal of WILD. You see, your body goes into SP every single night when you fall asleep, that way you don’t act out your dreams in RL. WILD is you keeping your mind awake while your body goes to sleep, so SP is to be expected.
There are a few posts you’re going to want to look over:
The BIG WILD topic
The WILD FAQ
The BIG sleep paralysis and old hag topic