The text from Rav Steinsaltz I shortened because the beginning may not be relevant to women.

2] At the same time, the Gemara questions whether this is true, given the Mishnah in Masechet Niddah which teaches that fear stops a woman from menstruating. The Gemara’s explanation is that although a long-term fear may keep a woman from menstruating normally, a sudden shock may cause a woman to bleed.

A woman’s monthly menstrual cycle is dependent on hormonal activity which is directed by the brain. Severe emotional stress, like a long-term threatening situation, may cause regular menstruation to cease – even for an extended period – until the stressful situation has passed. At the same time, a sudden shock or severe emotional event may cause a woman to bleed outside of her normal cycle.

 This essay is based upon the insights and chidushim of Rabbi Steinsaltz, as published in the Hebrew version of the Steinsaltz Edition of the Talmud.  To learn more about the Steinsaltz Daf Yomi initiative, click here.