Since Shavuot marks the giving of the Torah, studying Torah has long been a Shavuot tradition. Based on a Midrash, the Jewish people have gone even one step further. The Midrash recounts how on the night before Matan Torah, the Jews encamped beneath Mount Sinai went to bed early. Since prophecy was generally connected to dream states, they thought that sleeping would be an appropriate way to prepare for the Big Day.

But, conclude the sages, the people were wrong; they should have been up all night quivering in anticipation. To correct this mistake of our forefathers, the custom of the "Tikkun L'eil Shavuot" - the "Reparation of Shavuot Night" arose. Every Shavuot, study halls across the world are full of people engrossed in the study of Torah throughout the night.

(For more on this, see the Ohr Somayach article, Why do we learn all night?)

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