Distractions?

Are you ever so absorbed by your work that you forget to eat, or to leave your office at night and go home? And I don't mean that you are busy and consciously decide to stay late, I mean that you actually forget you don't live in your office.

Sometimes when I am trying to solve some puzzle that has come up in my computations, or I am trying to figure out the meaning of something that I have read, I might spend a few days obsessing about it. Sometimes even some weeks. I go to sleep thinking about it and I wake up thinking about it. Needless to say, I don't sleep very well. But the answer to the above questions is no, I almost never forget to eat and I definitely never forget to go home after a day at the office.

However, many of my colleagues do. I know several people who leave the office only when their wives call them on the phone urging them to come home. I often wondered, while in graduate school and even now, if this almost inhuman ability to focus only on your work and nothing else is necessary to be a really good theorist. A certain absent-mindedness and detachment from reality is part of the image that most people have of a theoretical physicist: somebody who wears socks of different colours or maybe forgets to wear his socks altogether.
But how cut off from the real world do you really need to be?

I wonder this because I am just not able to keep my thoughts constantly focused on science, even when I am thinking about some really interesting problem. There will be always some other thoughts sneaking in like: What will I cook tonight? Do I need to go shopping? Or, I wonder if Professor X thought I was a fool when we talked yesterday... Should I put another ad for a babysitter? Maybe I should have some chocolate... (this goes under the excuse "cravings because I'm breastfeeding")

This happens even more now. I might be at home with my baby and suddenly have an idea about some physics question that has been troubling me, but it can also happen that I miss half of a talk because my mind goes wondering about things like what kind of parent I would like to be. So am I doomed to failure because of lack of mental discipline?

Of course a woman with the kind of focus on her work that seems to be required would find it impossible to have a family, or to give her children the kind of attention that I would like to give my son. I know a two physicists who have a daughter and it is the mom who usually goes to pick her up at school. When she needs her husband to go instead of her she calls him up a few minutes before he has to leave the office to remind him, because although he is a very loving father, he cannot be trusted to remember to leave on time. And guess which one of the two proceeded faster in his career.

But I didn't mean this to become a rant about women in science.
It is a fact that to be good at this job one needs to be passionate about it, but I just wonder how exclusive the relationship with work needs to be. I know that it is possible to do decent science while at the same time caring about your family, your house and a few other interests, but what about really good science? Is it only done by people who devote themselves exclusively to it? It doesn't sound like it should be true, but I don't know the answer.