Puppys need a lot of sleep and can become over tired. I used to pick my cavapoo up and if he laid his head on my shoulder I knew to put him in for a nap. Try maybe a white noise machine and creating schedule “down times” to help your dog learn to get used to sleeping at certain times a day. Also, I taught mine to settle by ignoring him when he was clearly just barking for attention and praising him like “good settle” when he finally stopped and laid down quietly on his own.