Do you think the split dose might be contributing to the insomnia? I know some people respond better to the split dose, and others not. I ask because my dad tried splitting the dose based on the suggestion of one of his doctors, but it backfired because he's very sensitive to the activating effect of prednisone. He was wide awake in the middle of the night, so he only tried it the one time before realizing he needs to take his full dose in the morning.