As someone with a four month old this really resonates with me. I got the best grades of my entire life the two semesters my wife was pregnant, despite having to spend time helping her cope with e.g. morning sickness and school at the same time. I take the night feedings now and find that I just don't need as much sleep as I used to. Some people have always functioned fine on 5 hours or so but I was never one of them. I'm forced to be efficient. My wife needs me to be there to give her a break from the baby on weekends and late in the evening, so I have to try and make every baby free hour count.