I’m pretty obsessive about being efficient because I think time is so short and life is so short and there are so many interesting and amazing things to do and experience.  So I don’t sleep very much.  I’ve always been a nocturnal person.  So I normally sleep at three or four in the morning and I only have about five or six hours’ sleep, which is probably not enough actually, as brain studies tell us, but there’s just so many things I need to pack into the day.  So the way I normally split it is that during the daytime I manage the company and have meetings and do administrative things and organizational things, and then when I get home, I start a sort of second day of work — after dinner, around about 10 p.m. — where I start thinking about all my creative things.  It’s when I read books or research papers, or write research papers, or come up with ideas about algorithms.  I would do that in the small hours of the morning.  I’ve always found myself at my best creatively in the small hours of the morning when everything is quiet.