Nightmare help

We have been through our share of nightmares, and have managed to come up with solutions to all (I REALLY enjoy my sleep and will ponder how to fix sleeping issues for hours!). Here's what we have conquered:
Kidnapping (Rylee's fear) - Had her watch me set the house alarm at night
Birds flying in and biting her bottom (Maddie, who else?) - reminded her that our dog, Cisco, eats birds
Monsters (Maddie's) - Created "monster spray" which made the suckers vanish

Now, our new nightmare is this: Maddie is absolutely scared to death that when she sleeps, her eyes will change colors, specifically that they will turn green. Todd had to sleep with her at naptime yesterday, and she has woken me up every night this week to make sure her eyes are still blue. Now...I have tried logic (do your arms/legs/hair change while you're sleeping...no? then your eyes won't either) but it's not working. She will start about an hour before bedtime with the panick "but my eyes will turn green!" I'm kind of lost on this one, but really ready for a solution so that I can sleep through the night again.....suggestions???????