There are no failures, look back at the attempt and learn from it. For example look at what posture you were in, and pick another one for your next attempt, and you might find a one that suits you better. It's not that the sleeping posture is key for WILDing, it's just that an more uncomfortable sleeping posture sometimes can work as training wheels for the practise of mantaining awareness. Sometimes when I sit in a sitting posture whining about a little annoying itch on my leg I think to myself "Tibetan monks sleeps on thin ropes, spikematts and on their heads, what's you excuse?" ^-^

But the most important thing that we also can learn from these monks, is the point that TheObserver also made.

Don't have any expectations or hopes or .. dreams. Just be in the moment and see where it takes you just be the observer and not the judger...

So what I kind of suggested to you here to was two things, one find a sleeping posture that is harder to fall asleep in (Go extreme if you want to, but the second step gets more difficult) and two find a way to endure that posture for a long time.

When the second step is achieved you can begin by sleeping consciously and this is done by relaxing but not judging, to be without thinking, to exist without analyzing, to practise the art of doing nothing rather than something.

Namaste and sweet (conscious) sleep.