I could have written this question in some other stack places, but prefer to do here because the affinity with the audience. I am the head of a research group, 38 years old, engaged in a lot of things and working on average 12 hours per day on research and all related stuff. My son (first one) was born last week and we really enjoy it. My only concern is: how will I be able to cope with my workload and scientific output after my paternity leave (in two weeks)? I really never thought about this and wonder whether other academics could give advice.
Can you produce as much, or even more, with less time available? Yes.
Is it easy? No.
What generic advice can be given? Little, especially in such short space. Numerous entire books have been written on the topic of time management. Read the advice of others, decide whether it can apply to you, try it out.
Now, the above isn't very helpful. Not in the short term, at least. Below are a few tips from my own experience, maybe you will find them helpful:
First, decide what your priorities are, what you are willing to compromise, what you aren't. When I read “engaged in a lot of things”, it sounds like a warning to me. Honestly, the first two years of a baby's life are hard on the parents. Social life is hard to maintain, work output too, etc. Decide which you want to keep most, and focus there. Don't set your expectations too high across the board.
Second, learn to say no. People at your department probably ask you to participate in all sorts of research-related work (committees, etc.). If you have been playing ball ’til then, probably they can understand if you say “I'm sorry, right now is not a time I can take some extra work, I need to focus on my family”. Don't use that as an excuse to get out of every commitment, or avoid anything that is thrown your way, but strategically get a bit more time that way. Most people are quite understanding of the hardship of having a newborn baby. (Or my colleagues and bosses are extraordinary people; knowing them, it's also quite possible!)
Delegate stuff. You lead a team, so you have some responsibility in sharing the load. You can try to offload yourself a bit, by getting others to step in.
Work whenever you can (read: when the baby sleeps). Adjust your work style. I'll give only one example: when the baby gets to cry real bad in evenings or at night, I noticed I could get her to sleep if I had her in a sling against my chest and rocked from one foot to the other:
(the sling was as in the picture, except I needed to be standing and rocking). Well, I put my laptop on top of a high table (bar table), and quickly adapted to type and rock the baby. That way, I had time to work at night, while her mother could rest. I wrote quite a few grant proposals and articles that way.
I was close to vote to close for this question, however, in view of the upvotes, I'll give my two cents.
I think you are asking yourself the wrong question. You should not ask "How will I be able to keep up with my workload and scientific output?" but rather
What I am willing to do for my work and for my family? How do I and the rest of my family should arrange our life including work hours, family time and all the rest?
You may come to the conclusion that a reduced scientific output may be a "good price to pay" for a richer family life. On the other hand, if you are pre-tenure for example, you may also reach the conclusion that a year or two of "not so rich family life" and more hours at work are worth it.