According to tradition, Shavuot—the two-day holiday that begins on the eve of the evening of May 25, the sixth day of the Jewish month of Sivan—marks the Israelites’ receiving of the Ten Commandments at Mount Sinai. These days, some Jews pull an all-nighter to study the Torah. Staying awake is said to be a response to a biblical commentary that says the Israelites slept so deeply the night before the Torah was revealed at Mount Sinai that they had to be awakened with thunder and lightning.