Hmmm, it has been rumoured that eating a large steak or meat meal before going to sleep will get you nightmares.
I can personally say that it works for me - lots of sweating throughout the night and interrupted sleep with repeating nightmares. Having 400 grams of minced meat an hour or two before going to bed does the trick for me.
(of course, who would eat that much late in the night anyway...).
So, maybe you have trouble digesting all that protein. Try some digestive aid (enzymes or lots of fiber)?