the same happens on me! I used to need to wake up 3 times at night to eat, 1am, 3am, and 5am! It was horrible, and it disturbed my sleep severely.
My OB told me, it was a message my body telling me that I wasn't eating enough. He advised me to eat as frequently as possible. So I forced myself to eat (it isn't easy, I don't have much appetite), I found that the more I eat in the day, the less frequent I need to wake up at night to eat.
Now I mananged to keep it down to once a night (from 3 times a night) and extend the hours of sleeping longer. I sleep at 10pm and only wake up at 5:30 or 6am to eat! I can sleep better and longer.
My advice is, eat at least 5-6 meals a day, because I eat a little each time, and try to snack on in between, just eat whatever you want to. Dr said it is crucial at this time that I EAT, and it doesn't matter what I eat.
I also make sure I don't go to bed empty stomach. And elevate my upper body to prevent acid reflux.
While typing this, I am eating a bowl of RICE!