3weeks old sleeping nonstop!

Usually after feeding he is awake almost for an hour or even more. But from last night, he has been sleeping nonstop except for when I feed him. After he eats 2oz he falls back asleep( he usually eats 3-4oz to go to sleep) . Last week, he would constantly eat and awake so I thought that was the growth spurt. And suddenly he is sleeping so much? Is this a part of the growth spurt?