I have this exact problem!!

I go to the loo about 1.30am and stay awake for at least 2 hours.... I thought this was strange but I feel so awake at this time. I find if I have a warm glass of milk and some cookies, I feel better as I get really hungry if im up longer than 15mins. I usually do some reading and soon enough I feel drowsy. Does anyone know if this lasts for the rest of the pregnancy?