Ellie,

<< I eat animal food for dinner between 4 and 5 PM
 and go to bed around 7, but I usually want something like a peach or
 mango and a fig or dates before I got to bed. I'm not sure if it's my
 old habit of popping sleeping pills at bedtime. >>

I've been told the carbs increase serotonin in the brain which aids sleep.
I've been told the protein increases dopamine which is more stimulating.  The
fruit may be to help you sleep by affecting your mood through brain
chemicals...

Aaron