What Makes A Child To Laugh In The Middle Of His Sleep?

My year old had fever and vomiting today. I gave him Tylenol and tried to get him to eat and drink. He fell asleep and then woke up laughing but no fever. When he stopped laughing, I asked him questions to check if he was oriented. He did fine. He fell asleep again later, then woke up, got up from bed, walked out of his room laughing. When he stopped laughing, I asked him where he was and his name and my name and all he said was he didn t know. Then he fell asleep again. He did not have fever. Is he having metabolic encephalopathy or delirium?