WarpMyMind

We're new to to this with her being the natural submissive. She recently tried listening to files. However she has fallen asleep 3 out of the 5 times she's tried to listen to the files. There haven't been any obvious warning signs of this happening. Thus far no evidence of the files having any effect. Any advice?

Let's see, if she falls asleep and wakes at the end she's not asleep but in trance. The questions is what files is she listening to, sometimes it's best to work with simple ideas and concepts. So, if she falls asleep and doesn't wake up, try listening when she's wide awake instead of evenings etc. If she wakes at the end, she's in trance.

If she's listening while laying down, have her listen while sitting up on a sofa or chair.

Agree with the others - what do you have her listening to, and with what kind of induction?
Maybe you should consider studying some techniques and hypnotizing her yourself, so you can map her response to what's actually happening.