He's hungry, he's growing, having a growth-spurt... so he needs it. It is his BODY saying he is hungry. He needs it. He is developing in MANY ways physically & cognitively. Even their immune system too.
Boys, can have VORACIOUS appetites. My son is like that, compared to my daughter. GINORMOUS appetite, and frequent. But he is a picky eater... but BIG appetite.
My Mom (Grandma) says: just watch when he is a teen... they eat LOTS more. This is nothing.
My Daughter on the other hand, ever since this past Summer... she gets hungry every 2 hours or so. Literally. At the beginning of Summer her height was below my shoulders. At the end of Summer... her height was ABOVE my shoulders. She grew by leaps and bounds. Height wise.
What you might want to do: is make a cooler or insulated lunch-bag tote and keep it upstairs... so when he does wake and is hungry, it is right there all ready... and you won't have to go downstairs in the wee hours of the morning. It is convenience at those early hours. That is what I used to do... with my son. Only our kitchen is upstairs.
Your son is normal. Our Pediatrician was un-phased by it and says it happens. Some kids have big appetites and metabolize it quickly. Their body tells them what they need.
The "good" thing about it all is this: My son KNOWS his body and KNOWS when he is "hungry" or not. He WILL tell me. No matter what hour. And he will only eat if he is hungry. So, I am glad. He really knows his body cues and can express it. Accurately.
Hunger phases/growth-spurts will come and go. But throughout childhood.
All the best,
Susan