This sounds pretty normal to me!!!! I don't think I had a good night's sleep from the day we got the visa right up until we moved into our rental in Mornington (and that was a month after arriving in Australia.)
I would wake up in the middle of the night and think about things that needed to be done or things that I had managed to achieve and then I would spend ages thinking about the fact that I didn't want to think about the goodbyes (if that makes sense!)
As long as you keep waking up and thinking that you still want to get to Australia then everything will be fine. It's when you are wide awake and that feeling of not wanting to go at all doesn't go away it could become an issue.
Keep thinking of the positives and your reasons for wanting to come here. Yes the goodbyes are tough but they really aren't forever - I was very close to my family and I think I am fortunate enough to be even closer to them now. We cherish the time we spend online together and look forward to their visit to us in 19 months time.
Felicity
