Q. Why is it supposed to be good to study Torah at night?
A. Before my teacher, Isidore Epstein of blessed memory, became a lecturer at Jews’ College in London and subsequently the College principal, he was the rabbi of an English provincial community. The president passed by the rabbi’s house late one night and was not impressed to see that the lights were still on in the study. He expressed himself quite forcefully in the morning that this was not the kind of rabbi the community wanted – one who did not know it all but still needed to sit up and study!
He was probably a good president, but he did not understand. No-one ever finishes studying and the rabbi needs time to study when there are no distractions or interruptions.
Rambam goes further (taking it for granted, as does the whole halachah, that study is for everyone, not just rabbis) and points out that learning at night has inherent advantages: “Even though it is a mitzvah to learn both day and night, a person acquires most of his wisdom at night. If one learns at night, the thread of Divine love follows him by day, as it is said, ‘The Lord grants His love by day and by night His song is with me’ (Psalm 42:9)”.
Rav Soloveitchik comments that at night there can be a struggle to concentrate and to push away disruptive thoughts but if one succeeds they deserve to sing with God.