I wouldn't do sprints on an empty stomach....sprinting is more anabolic, and not at all like a 60 min cardio session at mod intensity that's designed to burn fat. Sprinting without fuel is a good way to get hurt.
There can be a couple other things playing into your nausea. What are you eating before bed? If you are not getting adequate fuel BEFORE bed, you will be nauseated/hungry in the morning. I always get a protein before bed that has a variety of absorption rates...whey, soy, casein, egg, etc. This keeps me from being over the top hungry when I wake up. Add some Udos, or flax to that protein shake, and bye-bye hunger.
If this doesn't help, try something like sugar free jello before your workout. It's like the nutritional equivalent of nothing...although I prefer not to use it because I don't care for aspartame.