did you hear any clicking noises? Could be aliens!
Seriously though, flood lights would greatly help your situation. They get tripped by a sensor when someone walks in front of them and light up the area like it's noon. Dad's had them on his house for as long as I can remember. Seemed more to light up the stairs up our yard from the driveway more than anything, but security wise they're an A-1 deterrent.
Motion Sensors @ Home Depot