I had the exact same thing....I would wake up at 1am to go to the loo and then I'd be wide awake until 3.30am! I used to just go with it because it was useless (and majorly uncomfortable) to just stay in bed. I'd get up and check my emails, make lists of the things that were on my mind, have a drink and check this site. Then I'd go back to bed and usually, because I had everything off my mind, I would fall asleep pretty quickly.

However I had the luxury of an afternoon nap because I was already on maternity leave by your stage. I hope you can get some sleep. Have you tried a warm cup of milk or a small snack?