This year Hoshana Rabba begins on Saturday night, it is the last of the intermediate days of Sukkot. There is a custom to stay up studying Torah on Hoshana Rabba night. How did this custom develop? One theory is that the next day, on Simkhat Torah, we celebrate the completion of the yearly Torah cycle. Ideally, throughout the year everyone studies the weekly portion, but inevitably people fall behind. Hoashana Rabba is the last night to catch up and so people spend the night studying so they can truly celebrate Simkhat Torah the next day.