This is completely true. I was focused completely on work when I was at work when I had no kids. My first kid brought that building completely down. I would sit at my desk staring at the screen not knowing that time was even passing. I finally had to force myself to sleep at lunch in my car in the parking lot so I could focus enough in the afternoon to not get fired. Luckily it passed and I started getting sleep after a while. It is amazing the stuff you think and do when highly sleep deprived.