Do you have to feel tired to have a WILD in the afternoon?

I was wondering if you had to feel tired to have LDs in the afternoon using WILD? I've been recently trying to have afternoon naps but I just can't seem to fall asleep because my body doesn't feel tired. Do you have to feel tired, or is it a case of getting into a very relaxed state?

You have to be able to sleep in order to WILD.