I don't know what time 3:30 AM is in Oz, but it's 4:30 AM here in the States. Sleep deprivation can really mess with your brain chemistry. I can also realte to the pain of depression. What I'll do is put on a pair of headphones & listen to some mellow music without lyrics (nature sounds are also good). They calm me down.

An example of nature sounds (there are other nature sounds if you do a YouTube):