I have this same dilemma because my daughter bathes at bedtime. I have moved her bathtime back by about 15 minutes and that has helped.
While her hair is still very wet, I rake through Mixed Chicks leave-in
and then scrunch out the excess water with a microfiber towel. That has made a huge difference. Just be sure to squeeze and not rub the towel on the hair. Then I scrunch in just a little gel over the top, so it dries crunchy while she sleeps to help hold the curl (someone on the 3c board suggested the gel). If we have time and if she is in the mood, I sometimes diffuse just a little before bed.
Squeezing out the water with the MF towel has been the biggest help, though.
In general, I have found that adding more moisture to her hair has helped immensely even after she sleeps on it. The hair is in better shape and is less "messed" and tangly when she wakes. Now, I wash her hair at the beginning of her bath and let the conditioner sit on her hair the entire bath, then rinse it at the end.