I am not sure it is a physiological disorder though. Like I said, I think if you compeltely concentrate on your work in a calm manner, you will get the work done. It is the distractions that could cause you to think of other things, such as sex. Once you are done with work, well, you are likely to be extremely horny, so reward yourself with sex.
You can also try creating goals for yourself. I think it was Anthony Burgess (writer) who said he is an extremely lazy man but gets his work done by promising himself a Martini at the end of the day after writing every 1000 words or something like that. You can do the same, reward yourself with a hot fuck at the end of the day.