Something that I understand all to well my friend. I get those several times a week and some in the day as well. Ever since some medical issues came up with my heart I wake up with an elevated heart rate a couple times a week, usually with a panic attack. It really sucks...
They can give you pills to sedate you when you have one, problem is if you work in the morning they make you really groggy. If it's two in the morning I tend to take a shot of vodka or two, calms you down fast and gets me back to sleep and come six in the morning I'm good to go. This is just what I do, and not recommended by any doctor and isn't medical advice! If it happens at four or five that definitely won't work though...
I feel for you, hopefully the treadmill will be easy to put together. Just try to keep that stress down the best you can.
!DHEDGE