I would strongly suggest that you go get a hotel room. Your best bet is the Sheraton Gateway hotel that is connected to Terminal 1 buy a LRT (monorail). It's a 4 minute ride from the hotel to Terminal 1.
If you arrive at the baggage dropoff by 7am you will have plenty of time to clear US customs. Also, in Canada there is a seperate line-up for US citizens so the wait will be short.