So at 4am your running on zero fuel, although this works for some people, maybe this is why you feel like your running out of energy, an eating plan for 4am runs will be tough unless you want to get up at 3am to eat, all it would take is a mouthful of food, I would suggest buying a 9bar and just taking a bite as soon as you can when you wake, giving yourself time to digest it a bit before your run, just an idea
I was drinking a coffee half hour before my runs as I had read how helpful it was, I woke up late for a park run one Saturday so never had time for the coffee omg I ran so much better and had so much more energy, the point I'm trying to make is, you have to experiment because different thing will work for different people
The fella that runs my running club swears by 3-1 rule as he calls it, he is an ultra marathoner and knows a bit, he has a very easy week every 4th week, he says it really makes a difference to his energy levels in general