Sleep

Is there something that happens at 6 months to cause baby to not sleep? He was sleeping 5pm to 4 or 5 am then eating and going back to sleep till 7 or 8... the last week has been miserable. He goes to sleep at 5 pm but wakes up at 6 or 7pm. I go and comfort him and get him back down and he sleeps till anywhere from 1:30 to 3 am. I’ll get him and change his diaper and feed him and put him back down but then he’s up every hour till I finally give up around 7. I’m exhausted and I’m just wondering if things will go back to our normal?