Humans sleep because we need to sleep.  We get tired and fatigued.  We sleep to get refreshed.  We tend to see God as just like us just way way way way bigger … but God is not like us - God is not comparable to anyone or anything else in all of creation.  He has zero needs - He’s completely self sufficient.  
 
King David and the prophet Isaiah write of God’s power and ability and while He's definitely way way way way bigger than us - He will never get fatigued or sidetracked and He won’t daydream or get caught up in the Instagram rabbit hole and leave us vulnerable.  Which means we can find rest during the day and even sleep at night because He Can’t.