I started to take a nap after lunch on Saturdays several years ago, partly in order to supplement lack of sleeping time on weekdays. I usually sleep six hours on weekdays (I go to bed at 23:00 and get at 05:00), but I seem to need seven and a half hours of sleeping daily. When I started the habit of taking a nap on Saturday afternoons, I used to sleep only for one and a half hours, but these days I sleep for three hours.
Gradually I came to allow myself to start this habit on Fridays. Since I started my sabbatical this academic year, I often find it difficult to resist the temptation of taking a nap on weekdays, too if I take lunch at home, which I usually do after the Talmud class at the yeshiva in the morning. So I end up sleeping seven and a half hours when I take a nap after lunch on weekdays.
Taking a nap seems to be a healthy habit, especially in the early afternoon, when our brain becomes less active than in the morning and late afternoon, but it also seems to be a waste of time. Once I finish my sabbatical, this habit will never be an option at all, but I would like to stop it even now so that I may be able to function properly after lunch next year.
So I am racking my brain over how to really stop this seemingly healthy but time-consuming "luxurious" habit of taking a nap on weekday afternoons. There seems to be only one simple solution - to start working at some public library. When I started my sabbatical, I originally planned to take with me a lunch box I would prepare in the morning and go to one of the libraries of the Hebrew University of Jerusalem after the Talmud class at the yeshiva. But because I was too lazy to prepare a lunch box in the morning and did not waste my time taking a bus to and from the library, I found myself returning home directly from the yeshiva, preparing lunch then and, alas, succumbing to the temptation of taking a nap afterward.
But the question remains whether I will be able to start working efficiently after lunch without taking a nap. One (or probably the only) possible compromise or solution is to take the so-called "power nap", which lasts 15-30 minutes. It seems to maximize the benefit of a nap versus time. I can probably use the time of my bus ride from the yeshiva to the university library, which lasts about 15 minutes. Actually, I am reminded now that when I taught at Bar-Ilan University, I often took a nap on my way back to Jerusalem and this was so refreshing.