The practice called tikkun leyl Shavuot comes from the kabbalists of Tzfat, who decided that the way to celebrate the revelation of the Torah at Sinai was to stay up all night studying. (A tikkun is a healing, as in the phrase tikkun olam, healing of the world. Leyl Shavuot just means "Shavuot Night.") Some have argued that the advent of coffee had a lot to do with the institution of the custom.

One midrash explains that the Israelites slept late on the morning they were meant to receive the Torah, and Moses had to awaken them, so in order to avoid a repetition of that problem the mystics opted stay up all night instead! Another compares the covenant of the Torah to the covenant of a marriage. At Sinai, the story goes, the Torah (bride) and Israel (groom) were joined in eternal union. Just as a bridegroom was expected to stay up all night in feverish preparation for his wedding, the mystics kept a vigil of study until dawn brought their Scriptural bride. Another interpretation is that Torah is the ketubah, or marriage contract, between God and the people Israel--in which case Shavuot is our collective wedding anniversary. Yet another tradition holds that the skies open for an instant in the middle of the night, and all prayers uttered then will be answered.

The original tikkun leyl Shavuot practice was developed, in medieval years, into a recitation of verses from every single parasha (weekly portion) of Torah, along with other special excerpts, the entire book of Ruth, and some sections of the Zohar which compare revelation with union. In many Orthodox and Hasidic communities, the practice still holds, according to that very blueprint.

As part of the pendulum swing back towards reclaiming traditional observances, liberal communities like mine are increasingly adopting the practice...though we usually focus more on study than recitation, and we may define "Torah study" fairly broadly. To most of us, studying fewer texts in a deeper way sounds more satisfying than glossing over the surface of eight hours of recitation. (We don't have the stamina, or the chops, for the traditional recitation-fest.)

Contemporary commentators see a natural progression between the medieval observance and the way many communities hold their study sessions now. "What is unfurled in this sprawling canvas teeming with texts is the implicit affirmation that each and every aspect of Judaism is but a branch of the original tree of life planted by God at Sinai," writes Ismar Schorsch, chancellor of the Jewish Theological Seminary. "The freedom to interpret the infinite meaning of God's words is the sap which has sustained and yielded this luxuriant growth."

Many commentators, Zalman Shachter-Shalomi among them, have noted that while God's role was to give the Torah at Sinai, the role of the Israelites was to receive it...and that just as Passover enables us to re-live the Exodus as if we ourselves had been freed from slavery, Shavuot enables us to re-live the experience of receiving the Torah as if we ourselves had stood at Sinai. We affirm that our freedom has a positive, active connotation: we're not just passively freed from slavery, but we actively free ourselves towards mature, adult engagement with our tradition.

As reasons to lose sleep go, this is a pretty good one, I think.