I tried to go a WBTB/WILD a few nights ago. So after I woke up and tried to get back to sleep, I decided to try one of the methods that says to focus on hypnagogic imagery (colors, dots, flashes, images, etc.) while laying completely still. The thing is, I don't notice any colors/dots/flashes/etc. when I close my eyes. I stayed there for a long time and I just saw complete blackness. I observed this for myself every time I lay in bed to do WILD or even throughout the day when I closed my eyes to observe what would happen - nothing, just blackness. Is this normal?