Shavuot is the holiday that celebrates the Jews receiving the Torah at Mount Sinai. There are not many practices or rituals involved with Shavuot, but one of the few practices is תיקון ליל שבועות (tikkun leil Shavuot), which is the custom of staying up all night to study Torah. After the holiday meal, many synagogues and yeshivas have special classes throughout the night of Shavuot. Aside from the obvious answer of "we're commemorating the Torah," why does this practice exist? Why do we specifically stay up all night to study Torah, especially when there is the entire day to do so?
The origins of the practice are of fascination. The first mentioning of תיקון ליל שבועות is in the Zohar, which is a well-known Jewish mystical text redacted by R. Moshé ben León (13 c.). The premise behind this practice was that one would be ready to receive G-d during morning services because so much time was spent preparing their minds and hearts. As a result, this mystical practice became popular throughout Spain. R. Josef Caro, who authored the halachic opus Shulchan Aruch, imparted the custom to many Jews throughout his travels, and word began to spread about this practice. It also helps that during this time period, coffee was introduced, which made it all the easier to pull off an all-nighter. Magen Avraham took the mystical elements out of the practice by saying that this custom is to rectify the mistake the Israelites made by sleeping the night before they received the law at Mount Sinai (Midrash Shir HaShirim, Ch. 1, 12:2). Over time, the practice spread and is now a staple of Shavuot practice. Although some use a fixed text, most people take the opportunity to study whichever Torah text or Jewishly related subject matter that one wishes.
Looking at the history of תיקון ליל שבועות is intriguing because I like how Jewish practices evolve and how we create our own traditions over time to express our religiosity and spirituality. However, I'm not convinced by the "traditional reasons" for תיקון ליל שבועות. For one, this was a practice initially only done by the very pious (חסידים) [Torah scholars]. This was not initially created with the layperson in mind, but it evolved that way. Two, it does not explain why an all-nighter has more of an effect on G-d's willingness to receive our prayers in synagogue the following morning. It seems analogous to a student preparing last-minute for a very important exam. Aren't we supposed to take the seven weeks of the omer to spiritually prepare instead of doing "last-minute cramming?" Even the Magen Avraham's explanation of תיקון ליל שבועות leaves something wanting. Why do we have to make up for a mistake that ancestors from so many generations ago made? Given that we are responsible for our own errors and sins, does it not seem excessively punitive to take on the penalty of someone else? It makes me wonder if a better reason for the practice can be devised.
One obvious answer is that Jews are meant to live a life of Torah. Torah study is such an important mitzvah that the Talmud states that one who studies the Torah is equal to the sum of performing all other mitzvot (Shabbat 127a). Although we are not going to receive the Torah at Mount Sinai this Shavuot, this Shavuot can be taken as an opportunity to rededicate one's commitment to Torah. I like these answers, and I certainly think that Torah study is important, but I still ask myself "why all night?"
The best answer I could come up with is that we would normally study it during the daytime or possibly after work. But the wee hours of the morning? Those who are very pious very well might be studying at all hours of the day, but as for the vast majority of Jews, not really. Not only is the evening when one typically sleeps, but deciding to study during the wee hours of the morning takes us out of our comfort zone. Studying that late puts in a different frame of mind, which has the potential to change our perspective on Torah. On the holiday that commemorates Torah, a day which we have all sorts of time, we we have so much alacrity and commitment that we are willing to truly exert ourselves to show G-d jut how much we love Torah and serving Him. Whichever texts you may decide to study, may your תיקון ליל שבועות be one of meaning and one that brings you closer to G-d.