What @deckroth2001 said! That's what they told me to do when I was in the hospital. You just gotta get them nakey and uncomfortable so they stay away. And rub his shoulder when he starts to doze off

change baby and keep baby undressed and nurse. you can rub babies face to keep stimulated and awake

Try to wake him every hour and nurse, even if it's only for a couple minutes. Also, make sure to pump as much as possible.

That's what they do. As long as they get a little and have enough wet diapers, they're alright. They sleep a lot at that age.