Well, keep in mind you have to fall asleep in order to WiLD obviously. I'm not sure if you're trying to WiLD in a position you don't normally fall asleep in, usually side sleepers have some problems performing WiLD techniques while laying on their back. You may not notice it, but your body may not be comfortable/relaxed enough to fall asleep.

Roll over a short amount of time after you would usually fall asleep without performing any techniques.
If you're a person who falls asleep after laying down for 10 minutes on average, try to roll over every 20ish.

Keeping your mind active is ok; it's getting your body comfortable.